MTL Instruments MTL700 Operating Manual

Instruction Manual

INM700

MTL700 and 700P Series shunt-diode safety barriers

iii

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 BARRIER SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3.1 The MTL700 and 700P Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3.2 General specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3.3 Additional specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3.4 Common specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.5 Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.6 Enclosure specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 SAFETY CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.1 General safety requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.2 Safety checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 MOUNTING THE BARRIERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ENCLOSED SYSTEMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5.1 Fitting the barriers into the enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5.2 Mounting the enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6 MOUNTING THE BARRIERS (UNENCLOSED SYSTEMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.1 The MTL700 and 700P Series accessories range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.2 Constructing the installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.3 Using SMC7 surface mounting clips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.4 MK2 mounting kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.5 MK5, MK12 and MK20 mounting kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

7 WIRING INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.1 Glanding cables into enclosures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.2 Earthing the barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3 Connecting non-hazardous (safe) area cables to barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.4 Connecting hazardous-area cables to barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.5 Cable parameters for MTL700 Series – BASEEFA(ATEX) & FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

7.6 Entity concept parameters for MTL700 Series – FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

7.8 Entity concept parameters for MTL700P Series – FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

7.9 Final check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

8 MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

8.1 Routine inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

9 FAULT-FINDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

9.1 Power supply check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

9.2 Barrier resistance test (not MTL702, 705, 706, 707, 707P and 708) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

9.3 Earth faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

9.4 Faults between barrier channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

10 THERMOCOUPLE AND RTD TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

10.1 Thermocouple circuit testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

10.2 Resistance thermometer detector circuit testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Contents Page

INM700-10 June 2005

continued overleaf

11 BARRIER TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

11.1 Multimeter tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.2 Constant-current tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.3 Tests for the MTL702 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.4 Tests for the MTL705 and 706 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.5 Tests for the MTL707 and 707P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.6 Tests for the MTL708 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

11.7 Test tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

APPENDIX A: ATEX certification informATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

CONTENTS PAGE

INM700-10 June 2005

1 INTRODUCTION

This instruction manual contains the information necessary to install, maintain, fault-find and test MTL700 and MTL700P Series shunt-diode safety barriers. Section 4 of the manual contains a checklist which highlights all the important safety factors that should be considered when using MTL700 and 700P Series barriers to interface between non-hazardous (safe) and hazardous areas. All users should read this section, and particularly the checklist, before commencing work on the barrier installation.

For further applicational information concerning the theory and use of shunt-diode safety barriers, users are recommended to read the following MTL publications:

Application Note AN9003, A user’s guide to intrinsic safety; Application Note AN9007, A user’s guide to shunt-diode

safety barriers (MTL700 Series); MTL Intrinsic safety catalogue covering MTL700 and 700P Series

barriers, and enclosures, parts & accessories; CD700 customer drawings, for additional installation informa-

tion.

These publications and a comprehensive selection of MTL technical papers (TPs) can be obtained from the company’s Publicity department on request: TP1064, 1076, 1082, 1083 and 1106 are particularly relevant. Copies of the apparatus and system certificates issued by the various certifying authorities are also available.

2 DESCRIPTION

MTL700 and 700P Series shunt-diode safety barriers are 1-channel or 2channel devices that employ intrinsically safe techniques to allow electrical signals to be passed between non-hazardous (safe) and hazardous areas. They achieve this by limiting the transfer of energy in one direction to a level that cannot cause ignition of explosive atmospheres.

Barriers that are connected in series with lines going to a hazardous area will protect wiring and equipment in that area from any faults occurring in the non-hazardous (safe) area, thus permitting a wide range of measurement and control operations to be undertaken safely.

Applications of MTL700 and 700P Series barriers include the protection of installations containing non-energy storing uncertified

devices such as switches, thermocouples, resistive sensors, photocells and LEDs, or separately certified ‘energy storing’ apparatus, for example ac sensors, transmitters and I/P converters. The barriers also enable maintenance work or calibration to be carried out without further precautions, and they permit non-hazardous (safe) area equipment to be worked on safely as and when necessary, with the minimum of restriction.

A range of five polycarbonate enclosures is available to provide environmental protection for barriers where required, and a Type N approved steel enclosure also is available to permit the barriers to be installed in Zone 2 areas. Enclosures and other accessories are fully described in this manual.

3 BARRIER SPECIFICATIONS

3.1 The MTL700 and 700P Series

The series consists of a carefully tailored range of application-orientated models, most polarised positively but some negatively and some nonpolarised. There is also a ‘dummy’ barrier. Basic circuits, specifications and approvals for each model are given in sections 3.2 to 3.5.

In 1992/3 a range of MTL700P higher-power barriers was introduced and is listed under 3.2 General specifications. The MTL700P Series barriers complement similarly numbered MTL700 Series barriers but deliver more power into hazardous areas. The series covers two distinct types: one type is designed for IIC gas group areas while the other is for IIB gas groups. The additional power available with the IIC units is made possible by a change in the BSI’s interpretation of the requirements of EN 50020 which brings it into line with other European authorities. It also corresponds with the requirements of North American standards.

The MTL700P barriers are mechanically identical to the MTL700 Series barriers and are therefore compatible with all MTL700 Series accessories.

Seven ‘key’ MTL700 Series models are highlighted in the sales literature as meeting most process control requirements. These models and their applications are listed in table 1. The literature also cross refers to MTL700P Series barriers where a higher-power barrier application may be required.

MTL700 & 700P SERIES INM700-10 SHUNT-DIODE SAFETY BARRIERS June 2005

MTL700 Series shunt-diode safety barriers

INM700-10 June 2005

To minimise spares stocks and simplify maintenance procedures it is worth noting that the ‘key’ barriers can often be used in place of other models: the MTL706+ can replace the MTL702+ provided that the transmitter is certified for a Umax:in of at least 28V and the transmitter and its lines require no more than 15V to operate. Both are nearly always the case. The MTL706+ consumes less current than the MTL702+ and allows 2-way communication with most ‘smart’ transmitters. Note that when undertaking the MTL702/706 substitution, terminals 3 and 4 of the MTL706 are reversed in polarity to those of the MTL702.

The MTL707+ can replace the MTL787+ provided only that the small extra voltage drop can be accepted. It accepts power supplies up to 35V without blowing its fuse. The MTL708+ can replace the MTL728+ with the same provisos and advantage, and also that the 1mA leakage current through the 708’s electronic protection network is acceptable.

The MTL787S can always replace the MTL787+ and drops 1.5V less at 20mA. Also, under most circumstances it can replace the MTL788+ for use with 2-wire, 4/20mA transmitters.

Table 1: Key barriers summarised

Table 2: Patents issued to MTL700 and 700P Series barriers

3.2 General specifications

3.2.1 Terminology (Notes 1 to 7 in tables 3 and 4) 1 Safety description. The description of a barrier, eg, ’28V

300Ω 93mA’ refers to the maximum voltage of the terminating Zener or forward diode while the fuse is blowing, the minimum value of the terminating resistor and the corresponding maximum short-circuit current. It is an indication of the fault energy that can be developed in the hazardous area – not the working voltage or end-to-end resistance.

2 Polarity. Barriers are polarised ‘positive’ (+), ‘negative’ (–), or

‘non-polarised’ (ac). Polarised barriers accept and/or deliver non-hazardous (safe) area voltages of the specified polarity only. Non-polarised barriers support voltages of either polarity applied at either end.

3 End-to-end resistance. This is the resistance between the two

ends of a barrier channel at 20°C, ie, of the resistors and the fuse. If series diodes or transistors are present, their voltage drop (transistors ON) is quoted in addition.

4 Working voltage (Vwkg). This is the greatest steady voltage,

of appropriate polarity, that can be applied between the non-hazardous (safe) area terminal of a ‘basic’ barrier channel and earth at 20°C for the specified leakage current, with the hazardousarea terminal open circuit.

5 Maximum voltage (Vmax). This is the greatest voltage, of

appropriate polarity, that can be applied continuously between the non-hazardous (safe) area terminal of any barrier channel and earth at 20°C without blowing the fuse. For ‘basic’ barriers, it is specified with the hazardous-area terminal open circuit; if current is drawn in the hazardous area, the maximum voltage for these barriers may be reduced. The ‘ac’ channels of ‘basic’ barriers and most channels of overvolt-protected barriers withstand voltages of the opposite polarity also – see circuit diagrams.

6 Fuse rating. This is the greatest current that can be passed con-

tinuously (for 1000 hours at 35°C) through the fuse.

7 Star connection. In star-connected barriers, the two channels

are interlocked such that the voltage between them cannot exceed the working voltage, Vwkg.

8UM(not shown on the tables). UM defines the maximum voltage

that can be applied to the non-intrinsically safe connection facilities of associated apparatus without invalidating intrinsic safety. For all MTL700/700P barriers, UM is 250V rms or dc with respect to earth.

3.3 Additional specifications

3.3.1 MTL702 additional specification Supply voltage

20 to 35V dc, positive w.r.t. earth

Voltage available for transmitter and lines (at 20mA)

Vsupply minus 8V, limited at 16V

Voltage available for load (at 20mA)

Vsupply minus 5V

Load resistance

850Ω maximum

Output impedance to load

>1MΩ

Calibrated accuracy (at 20°C with 250ΩΩload)

0.05% of maximum output, including non-linearity and hysteresis

Zero temperature drift

<0.005% of maximum output per °C

Span temperature drift

<0.005% of maximum output per °C

Supply current

8 to 40mA + 10mA maximum at 20V 8 to 40mA + 20mA maximum at 35V

3.3.2 MTL706/705 additional specification Supply voltage

20 to 35V dc, positive w.r.t. earth

Output current

MTL706: 4 to 20mA MTL705: 0 to 20mA

BARRIER UK PATENT USA PATENT

MTL706+ 2205699 4967302 MTL707+ 2245439 -

and 2210521 MTL708+ 2210521 MTL787S+ 2210522 4860151 MTL707P+ 2210521 4860151

and 2210522 MTL787SP+ 2210522 4860151

TYPE APPLICATION KEY BARRIER

Analogue Resistance temperature detectors 755ac input (low-level) Thermocouples, ac sensors 760ac Analogue Controller outputs, one line earthed 728+ output Controller outputs, neither line earthed 787S+

dc power supply

26.0V 20–35V

Analogue Transmitters, 2-wire, 4/20mA 787S+ 706+ input (high-level) Digital (on/off) Switches 787S+ 707+ input Digital (on/off) Solenoids, alarms, LEDs 728+ 708+ output

Figure 1: MTL702 basic circuit

60mA max

Current

mirror

4/20mA



+Vref

50mA

Regulate

100mA

4/20mA

50mA

850W max.

+35V max.

INM700-10 June 2005

Voltage available for transmitter and lines

15V minimum at 20mA with 22V supply

15.5V typical at 20mA with 24V supply Note: voltages are negative w.r.t. earth

Load resistance

MTL706: 250Ω ±5% MTL705: 300Ω

(can be greater if reduced transmitter voltage is acceptable)

Accuracy

±2µA under all conditions

Supply current

35mA typical at 20mA with 24V supply 40mA maximum at 20mA with 35V supply

3.3.3 MTL707/707P additional specification Supply voltage (Vs)

10 to 35V dc, positive w.r.t. earth

Output current (Iout)

Up to 35mA available

Maximum voltage drop (at 20°C, current not limited)

MTL707

out

x 370Ω + 1.5V, terminals 1 to 3

out

x 50Ω + 2.1V, terminals 4 to 2

MTL707P

out

x 200Ω + 0.2V, terminals 1 to 3

out

x 18Ω + 1.3V, terminals 4 to 2

Supply current

MTL707

out

+ 1mA max, Vs <26V

Limited at 50mA, Vs >28V or low load resistance

MTL707P

out

+ 2mA max, Vs <25V

Limited at 50mA, Vs >28V or low load resistance

3.3.4 MTL708 additional specification Supply Voltage (Vs)

10 to 35V dc, positive w.r.t. earth

Output current (Iout)

Up to 35mA available

Maximum voltage drop (at 20°C, current not limited)

out

x 370Ω + 1.5V, terminals 1 to 3

Supply current

out

+ 1mA maximum, Vs <26V

Limited at 50mA, Vs >28V or low load resistance

3.4 Common specification

Ambient temperature and humidity limits

–20°C to +60°C continuous working –40°C to +80°C storage 5 to 95% RH

Leakage current

For ‘basic barriers’ with a working voltage of 5V or more, the leakage current decreases by at least one decade/volt reduction in applied voltage below the working voltage, over two decades. For the MTL755 it decreases by at least one decade for a 0.4V reduction in applied voltage.

Terminations

Terminals accommodate conductors up to 4mm2(12AWG) Hazardous-area terminals are identified by blue labels

Colour coding (barrier top)

Grey: Non-polarised Red: Positive polarity (and MTL791) Black: Negative polarity Black (red label for safe area terminals):

positive supply, negative to transmitter (MTL706)

White: Dummy barrier (MTL799)

Weight

125g approximately

Mounting and earthing

By two integral M4 x 9 tin-lead plated steel fixing studs and stainless steel self-locking nuts (provided)

Figure 2: MTL706 basic circuit

Figure 3: MTL707 basic circuit (see Table 4 for MTL707P basic circuit)

Figure 3: MTL708 basic circuit

Figure 5: Barrier dimensions in mm

Hazardous area terminals

Non-hazardous

(safe) area

terminals

40mA max

50mA

Current limit

Negative

4/20mA



50mA

Regulate

4/20mA

50mA

+35V max.

250W

±5%

out

Current

limit

1 mA max

50mA

+35V

max

LED,

alarm,

solenoid,

etc

out

3 4

25.0

11.57.5 7.5

49.2

9.0

85.0

93.5

Current

limit

1 mA max

2 1

50mA

61.5

+35V

max

2 1

14.2

INM700-10 June 2005

Model Max. end

No. Safety description Polarities Application Basic circuit -to-end V

wkg

max

Fuse

available Hazardous Safe resistance 10(1)µµA rating

MTL V

ΩΩ

mA + – ac

ΩΩ

VVmA

702 25 200 125 √ Transmitters – – 35

†705 28 300 93 √ Transmitters – – 35

706 28 300 93 √ Transmitters ––35 707 28 300 93 √ Switches ––35

28 diode – –––50

708 28 300 93 √ Solenoids, alarms, LEDs ––35 50

710 10 50 200 √√√ 6V dc & 4V ac systems 85 6.0 6.9

715 15 100 150 √√ 12V systems 155 12.0 13.0 100 722 22 150 147 √√ 18V dc systems 185 19.0 20.2 50 728 28 300 93 √ Controller outputs, solenoids 340 25.5 26.6 50 728 28 300 93 √√ Transmitters 340 25.5

26.6

751 1 10 100 √ Active dc & ac sensors 20 0.3 2.0 250

1 10 100 (low impedance receivers) 20 0.3 2.0 250

755 3 10 300 √ Resistance temperature 18.0

(0.6) 3.6 250

3 10 300 detectors 18.0

(0.6) 3.6 250

758 7.5 10 750 √√ Gas detectors 18 6.0 7.0 200

7.5 10 750 18 6.0 7.0 200

761 9 90 100 √ 145 6.0 7.5 100

9 90 100 145 6.0 7.5 100

764 12 1k 12 √√√ Strain-gauge bridges 1075 10.0 10.7

12 1k 12 1075 10.0 10.7

766 12 150 80 √ 185 10.0 11.2 50

12 150 80 185 10.0 11.2 50

767 15 100 150 √√ 12V dc systems 155 12.0 13.0 100

15 100 150 155 12.0 13.0 100

768 22 150 147 √√ 18V dc systems 185 19.0 20.2 50

22 150 147 185 19.0 20.2 50

779 28 300 93 √√ Controller outputs 340 25.5 26.6 50

28 300 93 340 25.5 26.6 50

796 26 300 87 √√ Vibration probes 340 23.5 24.6 50

20 390 51 (MTL796 negative) 435 17.5 18.7 50

760 10 50 200 √ Active dc & ac sensors 85 6.0 7.4 50

10 50 200 85 6.0 7.4 50

765 15 100 150 √ 135 12.0 13.2 50

15 100 150 135 12.0 13.2 50

772 22 300 73 √ 2-wire dc & ac systems 340 18.0 19.7 50

22 300 73 340 18.0 19.7 50

778 28 600 47 √ 665 24.0 25.7 50

28 600 47 665 24.0 25.7 50

786 28 diode – √√ Signal returns 2.2V+30W 25.5 26.6 50

28 diode – 2.2V+30W 25.5 26.6 50

787 28 300 93 √√ Controller outputs, 340 25.5 26.6 50

28 diode – switches 2.2V+30W 25.5 26.6 50

787S 28 300 93 √ Transmitters 340 25.5 26.6 50

28 diode – Controller outputs, 0.9V+20W 25.5 26.6 50

switches

788 28 300 93 √√ 340 25.5 26.6 50

10 50 200 85 6.0 6.9 50

Transmitters 340 25.5 26.6 50

788R 28 300 93 √√ 85 6.0 6.9 50

10 50 200

791 11 51 216 √ H1 (31.25kbit/s) Fieldbus 62.6 10V (at 50µA) 10.5 100

11 51 216 √ installations 62.6 –10V (at 50µA) –10.5 100

799 Dummy barrier for securing cables for future installations

Table 3: Basic circuits and specifications for MTL700 Series barriers

(for notes 1 to 7 see 3.2.1 Terminology)

a: Tolerance ±0.15W at 20°C, channels track within 0.15W from –20 to +60°C. b: ac version 24.5V. c: ac version 7.4V. d: ac version 26.1V. e: ac version 11.2V. †: For new designs, use MTL706 *Diagrams show positive versions. All diodes reversed on negative versions. Additional diodes fitted on ac versions. Patents for MTL787S: UK Patent No. 2210522, USA Patent No. 4860151

12 3456

See 3.3

Additional

specification

768 & 779 require channels seperate in IIC

See

3.3

Additional

spec.

3 (26V:796)

4 (20V:796)

Star connected (Note 7)

787S

3 (28V)

4 (10V)

250W

Internal terminator

Terminal 1 & 2 open circuit

INM700-10 June 2005

12 3456

Model Gas Safety Polarities Basic circuit Max. Vwkg Vmax Fuse

No. group description available Applications end-to-end at rating

resistance 10(1)µA

(MTL) (V) (ΩΩ) (mA) (+) (–) (ac) hazardous safe (ΩΩ) (V) (V) (mA)

707P IIB 28 164 171 ✓ - - Transmitters See 3.3 additional 35 50

15 diode - Controller outputs specifications

710P IIC 10 33 300 ✓✓ - 8V dc systems 42 8.0 9.2 200

715P IIC 15 50 291 ✓ - - 12V dc systems 60 12.5 13.8 200

722P IIC 22 101 213 ✓ - - 18V dc systems 121 1 5 20.0 100

728P IIC 28 234 119 ✓ - - Controller outputs, 253 24.5 26.0 100

Solenoid valves

729P IIB 28 164 171 ✓ - - Controller outputs, 184 24.5 26.0 100

Solenoid valves

761P IIC 9 350 25 - - ✓ Strain-gauge 384 7.0 8.1 50

9 350 25 bridges 384 7.0 8.1 50

766P IIC 12 75 157 - - ✓ Strain-gauge 93 9.8 11.3 100

12 75 157 bridges 93 9.8 11.3 100

787SP IIC 28 234 119 ✓ - - Transmitters, 258 24.5 26.5 80

28 diode - Controller outputs, 0.9V+16Ω 24.5 26.5 80

Switches

Country Certificate/file no. (Authority) Standard MTL710 to 796 MTL702 MTL706 MTL707/708/787S Approved for

Argentina IAP CA 4.01 1989 INTICITEI 92A001 INTICITEI 92A001 INTICITEI 92A001 INTICITEI 92A001 [Ex ia] IIC Australia (QMD) CMA 1925-1981 QMD 85 6001 XSU* QMD 85 6124 XU Mining Australia (NSW M) CMRA 67/1982 MDA Ex. ia 1321 MDA Ex. ia 1411 MDA Ex. ia 1321 MDA Ex. ia 1321 Coal and shale mines Australia (SA) AS2380.7-1987 Ex 562 Ex 692 Ex 562X Ex 562X (Ex ia) IIC Brazil NBR 8447/84 CE.Ex-221/92a CE.Ex-220/92 CE.Ex-221/92 BR-Ex ia/ib IIC Canada (CSA) C 22.2, No 157 LR36637-14 LR36637-16 LR36637-26 LR366 37-20 Class I, II, III, Div. 1, A-G China (NEPSI) GB3836-1/7 GYJ93105 GYJ93105 GYJ93105 GYJ93105 (ia) IIC T6 Czechoslovakia (FTZU) CSN 33 0380 J02033 J02033 J02033 J02033 [Ex ib IIC] Denmark (DEMKO) EN 50 020 R75916* [EEx ia] IIC Hungary (BKI) MSZ 4814/7-77 87B2-018 87B2-018 87B2-018 87B2-018 [Ex ib] IIC Japan (TIIS) 1979 Rec. Pract. C10619 to C10636† 39286 Groups 2 and 3a, G5 Korea (KRS) LND03065-EL001 LND03065-EL001 LND03065-EL001 LND03065-EL001 [EEx ia] IIC Tamb = 60°C Poland (KDB) PN-84/E-08107 KDB Nr.91.009W† KDB Nr. 91.010W KDB Nr 91.011W KDB Nr.91.012W [Ex ia] IIC Romania (ISM) STAS 6877/4-87 ISM Nr. 90.2820 ISM Nr. 90.2821 ISM Nr. 90.2822 ISM Nr. 90.2820 [Ex ia] IIC Switzerland (SEV) EN 50 020 ASEV 84.14332X ASEV 84.14332X ASEV 84.14332X ASEV 84.14332X [EEx ia] IIC UK (BASEEFA) EN 50 020 Ex832452b Ex84B2307 Ex87B2428 Ex832452 [EEx ia] IIC UK (BASEEFA) (Systems) EN 50 039 Ex832469 Ex842308 Ex872513 Ex832469 [EEx ia] IIC UK (BASEEFA) BS 4683:Pt 3 Ex83453 Ex83453 Ex83453 Ex N II T6 in MT20N UK (BASEEFA, Indian vn) EN 50 020 Ex89C2346 Ex89C2347 Ex89C2346 [EEx ia] IIC UK (HSE (M)) EN 50 020 HSE (M) 8570006 HSE (M) 8570006 [EEx ia] I - coal mining UK (Lloyds Reg) Type Approved 86/00102 86/00102 86/00102 86/00102 All vessels registered USA (FM) 3610 Entity J.I. 1H8A1.AX, J.I. 1K4A1.AX J.I.0R6A1.AX J.I. 2P0A4.AX Class I, II, III, Div. 1, A-G

J.I. 2P0A4.AXc USA (MSHA) Classified 132011-17,20-31,40-44* 132010 Mining systems USA (UL) UL 913 E120058 E120058 E120058 E120058 Class I, II, III, Div. 1, A-G CIS (VNIIVE) GOST 22782.5-78 N 144 N 144 N 144 N 144 Ex ia/ib IIC

EN 50 020 & IEC 79-11

*MTL758 certification in hand a: MTL758 CE.Ex222/92, approved for BR-Ex ib IIC †including MTL787S b: MTL791 Ex94C2172 Note: UK BASEEFA is to CENELEC standards c: MTL791 J.I.4X0A4.AX, approved additionally for non-incendive Class 1, Div 2, ABCD

3.5 Approvals

Changes may have occured

since this document was printed. Check our web site for latest information – http://www.mtl-inst.com

Table 5: Approvals for MTL700 Series barriers

Table 4: Basic circuits and specifications for the MTL700P Series higher-power barriers

(for notes 1 to 6 see 3.2.1 Terminology)

Current

limit

50mA

+35V

max

2 mA max

out

INM700-10 June 2005

Country Certificate/File No.

(Authority) Standard IIB barriers (Gps C-G) IIC barriers (Gps A-G) Approved for

Australia (SA) AS2380.7-1987 Ex2065 Ex2065x (Ex ia) IIC Canada (CSA) C22.2, No.157 LR36637-58 LR36637-58 Class I, II, III, Div.1 Gps A-G

LR36637-66*

China (NEPSI) GB3836-1/7 GYJ93106 GYJ93105 (ia) IIC T6

(ia) IIB T6 Hungary (BKI) MSZEN 50 014 & 020 87B2-018 [EEx ia] IIC UK (BASEEFA to BS 5501:Pts 1&7 Ex92C2375 Ex92C2373 [EEx ia] IIC CENELEC standards) EN 50 014 & 020 [EEx ia] IIB UK (BASEEFA to BS 5501:Pt 9 Ex92C2376 Ex92C2374 EEx ia IIC CENELEC standards) EN 50 039 EEx ia IIB UK (BASEEFA) BS 5501:Pts 1&7 Ex94C2377 Ex94C2378 [EEx ia] IIC (to CENELEC standards), EN 50 014 & 020 held by MTL India USA (FM) 3610 Entity J.I.0W2A5.AX J.I.0W2A5.AX Class I, II, III, Div.1

J.I.5W0A3. AX Class 1,Div. 2 Gps A-D (MTL787SP) non-incendive

Table 6: Approvals for MTL700P Series high-power barriers (

see begining of Section 3.5 for warning of approval changes

)

3.6 Enclosure specifications

Table 7: Enclosure specifications

Obsolete products

*Certification/File No. for MTL787SP only

Specification MT2 MT5 MT12

MT24 MT32

MT20N Max. barrier capacity 2 5 12 24 32 20 Construction Polycarbonate: glass-filled base, transparent lid Sheet steel Finish Dark grey base Light grey base Mid grey painted Lid fixing 4 captive screws 6 captive Lift off floppy hinges,

screws 4 captive screws,

hasp for padlock

Protection: dust-tight waterproof IEC529:IP65 IEC529:IP67 Gland fixing 4 x 20mm holes

pre-drilled through Top and bottom gland plates detachable for drilling by user

top and bottom

Permitted location Non- Non- Non- Non- Non- Zone 2

hazardous hazardous hazardous hazardous hazardous BASEEFA certificate

(Safe) area (Safe) area (Safe) area (Safe) area (Safe) area No. Ex83453,

Certification - - - - - Code: Ex N II T6,

BS 4683: Pt 3, 1972

Mounting (see figure 7) Corner screws or plastic Plastic lugs screwed to base Fixed mounting lugs

lugs screwed to base plugged knockout holes, or

rear-fixing screws

Mounting kit provided 2 lugs + attaching 4 lugs + attaching As MT12 None

screws screws, 4 plugs but 6 off

Tagging facility provided None Tagging strip(s) with label(s) and seal(s) Cable trunking provided? No No No No Yes Yes ‘Take care’ IS label provided Adhesive front, inside lid Adhesive back, on lid Earth terminals provided:

Large (<16mm

, 6AWG) 0 3 3 3 3 3

Small (<4mm

, 12AWG) 3 3 6 12 16 10

Weight (ex barriers) kg: 0.36 1.08 2.20 4.61 6.83 12.62

4 SAFETY CONDITIONS

4.1 General safety requirements

All users of shunt-diode barriers should be familiar with the installation instructions given in a nationally accepted code of practice,

e.g. BS EN 60079–14:2003 in the UK, or Recommended Practice, e.g. ANSI/ISA-RP12.6 for the USA.

4.2 Safety checks

Table 8 itemises all the important checks which should be carried out to ensure the safety of a barrier installation. Diligent use of the checklist will avoid the possibility of any important safety consideration being overlooked when installing, commissioning, modifying or servicing an installation that uses MTL700/700P Series barriers.

MTL recommends that on completion of any work on a barrier installation, each item on the checklist is again checked out, preferably by someone other than the person who actually carried out the work.

Each item on the checklist is cross-referred to the relevant section of the manual to which reference can be made for more detailed information.

5 MOUNTING THE BARRIERS

(ENCLOSED SYSTEMS)

Although the construction of MTL700/700P Series barriers gives them IP20 protection, a higher IP rating and additional protection against mechanical damage and unauthorised modification can be provided by the ‘MT’ range of enclosures, which can mount up to 2, 5, 12, 24 or 32 MTL700/700P Series barriers in the non-hazardous (safe) area.

INM700-10 June 2005

A type ’n’ approved steel enclosure is available in the range for protecting up to 20 barriers in Zone 2 areas. The dimensions and specifications of the enclosures are given in table 7 and figure 6 respectively.

5.1 Fitting the barriers into the enclosure

Each enclosure is supplied ready-fitted with all the necessary accessories to allow immediate installation of barriers. To fit the barriers, remove the enclosure’s lid by releasing the captive screws (the MT20N enclosure’s lid is removed by also lifting it off its two hinges). Temporarily unclip the TGS7 tagging strip (not fitted on model MT2), then simply bolt each barrier via its two earth studs to the section of busbar provided, tightening all nuts to a torque of 2.3Nm using the ‘TQS7’ torque spanner or other suitable wrench. Note that these ‘Nyloc’ nuts will lose their anti-vibration feature after being tightened/released several times, so if possible avoid undoing them once they have been tightened.

Ensure that the barriers are mounted such that their hazardous-area terminals are adjacent to the row of terminals mounted alongside the busbar, or in the case of the MT5, the three small terminals mounted on the end brackets.

5.2 Mounting the enclosure

Depending on the model utilised, there are up to three different methods of mounting enclosures, and these are illustrated in figure 7 and described later. The enclosure specifications section 3.6 details mounting methods, dimensions and kit provided for each model.

Care should be taken when mounting enclosures to ensure the internal temperature does not exceed the maximum permitted ambient temperature for the barriers (i.e. 60°C). For this reason enclosures should not be mounted in areas where they will be subject to direct sunlight or other sources of heat.

5.2.1 Corner screws/plugged knockout holes (not MT20N)

With this method, enclosures are mounted from the front using screws or bolts (not provided). First, using a small screwdriver, pierce the corner knockouts from the rear of the enclosures (not applicable on MT2 and MT5; holes are already provided). Then, from the front of the enclosures, insert suitable screws or bolts through the 5mm diameter apertures made by the removal of the knockouts, and fix the enclosures into position. The mounting dimensions are shown in figure 6. Finally, on MT12, MT24 and MT32 only, insert the plastic sealing plugs (provided) into the holes above the screws, and push them firmly into place to seal the knockout apertures, so as to preserve the enclosure’s IP65 integrity.

107

Figure 6: Enclosure dimensions (mm)

Figure 7: Method of mounting a typical enclosure

Ø6

157

Ø6

MT12MT5MT2

172

MT20N

382

198

157

150*

Knockout hole, ø5

148

125*

125

ø6.5

198

100 175

175

272

25*

173*

200 (MT12)

Fixing lugs for MT12

The screw-on fixing lugs can be positioned as shown (left).

*Add 5mm to depth if fixing lugs are used.

310

475

170

305

HAZARDOUS AREA WIRING

SAFE AREA WIRING

407

150

INM700-10 June 2005

Item Check

No section:– Refer to

1 Before commencing the installation ensure that the safety documentation confirms 4.1

that the proposed system is fully certified (if applicable) and complies with the recommendations contained in the relevant sections of BS 5345 for the gas group, temperature classification and area classification required

2 Ensure that the barriers installed are of the correct type and polarity as 8.1

specified in the safety documentation

3 Ensure that all barriers are mounted the right way around 5.1 and 6.2

4 Ensure that all barriers are securely mounted on the earth busbar by checking the 5.1, 6.2 & 8.1

tightness of both mounting nuts on each barrier with a torque spanner

5 Ensure that all barriers are properly earthed in accordance with the safety 7.2 & 8.1

documentation and in compliance with the recommendations contained in BS 5345: Part 4

6 Measure the resistance between the barrier earth busbar and the main power 7.2 & 8.1

system earth and ensure that it does not exceed the maximum permitted resistance specified in the safety documentation

7 Carefully inspect all cables connected between the barriers and the 7.4 & 8.1

hazardous-area equipment; ensure that the cables are the correct type specified in the safety documentation and that they are connected to the correct terminals

8 Ensure that all hazardous-area cables are well secured and are segregated from all 7.4 & 8.1

other cables

9 Ensure that the permitted cable parameters for hazardous-area circuits are not 7.4

exceeded

10 Ensure that all hazardous-area apparatus and cables are either earth-free or 7.4

correctly bonded with an equipotential conductor

11 Ensure that all hazardous-area cables and cable screens are either terminated at 7.4 & 8.1

a barrier or connected to the earth rail

12 Ensure that all unused hazardous-area cables are connected to a dummy barrier 7.3

(MTL799) or otherwise safely secured to the earth rail (ERL7)

13 Ensure that all energy-storing devices installed in the hazardous area have been 7.4

independently certified

14 Inspect all tagging labels and ensure that they display the correct barrier types, 5.1 & 6.2

polarities and circuit loop numbers

15 Carefully inspect all cables connected to the non-hazardous (safe) area equipment and 7.3

ensure that they are connected only to the non-hazardous (safe) area terminals of the barriers.

16 Ensure that no non-hazardous (safe) area equipment is supplied from, or contains, 7.3

a source of potential with respect to earth that exceeds 250V rms or 250V dc under normal or fault conditions unless specifically permitted by the safety documentation. Note: one phase of a 3-phase supply of up to 440V is permitted as that value is the equivalent of 250V rms.

17 Ensure that all barriers are adequately protected from moisture, dust, dirt, vibration, 5.1 & 6.2

mechanical damage, unauthorised modification and excessive temperature variations.

18 Ensure that all enclosures in which barriers are mounted are effectively sealed and 5.2 & 7.1

that cable glands are correctly fitted.

Table 8: Checklist

INM700-10 June 2005

5.2.2 Rear-fixing (not MT2, MT5 and MT20N)

Enclosures are mounted from the rear with this method, using the M6 screws provided. First drill holes through the surface onto which the enclosure is to be mounted, positioned so as to align with the tapped holes at the rear of the enclosure. These positions are the same as for corner screws in paragraph 5.2.1 and are shown in figure 6. Then, using the M6 x 12 screws provided, fix the enclosure into place from the rear. It will be necessary to use longer M6 screws than those provided if the thickness of the material on which the enclosure is mounted exceeds about 6mm.

5.2.3 Fixing lugs

All models can be mounted on a flat surface using the fixing lugs provided.

On models MT2 and MT5 the two plastic lugs can be positioned on either pair of opposite sides, as shown in figure 6. They are attached to the rear of the enclosure by the self-tapping screws provided.

On models MT12 and MT24, the plastic lugs are positioned one in each corner, and each can be attached in any one of three positions (see figures 6 and 7). The lugs are attached to the rear of the enclosure using the screws provided. Model MT32 is similar but uses six lugs: one in each corner, and two midway along the enclosure’s length. This extra lug on each side should be fixed at right-angles to the enclosure’s side, in either one of the two mounting holes.

Model MT20N has fixed mounting lugs, whose centres are shown in figure 6.

6 MOUNTING THE BARRIERS

(UNENCLOSED SYSTEMS)

To simplify installation in circumstances where enclosures are not required, the parts needed are available either separately or as complete mounting kits for specified numbers of MTL700/700P barriers.

The range of accessories available for mounting MTL700/700P Series barriers as unenclosed systems is detailed in section 6.1. MTL certified customer drawings (CD701 Series) containing full specifications of each item are also available. Section 6.2 details the simple step-by-step procedure for constructing a comprehensive barrier mounting, earthing and tagging installation using the separate part accessories and section

6.4 gives the assembly instructions for the mounting kits.

6.1 The MTL700 and 700P Series accessories range

6.1.1 Earth busbar EBB7

Used for mounting and earthing MTL700/700P Series barriers. Available in 1-metre lengths, in nickel-plated brass.

6.1.2 Insulating mounting block IMB7

Used for mounting EBB7 earth busbars and insulating them from panel/structural earth to prevent invasion by fault currents. IMB7s are sufficiently high to provide tagging and earthing facilities for MTL3000 and 2000 Series interface units if required. They can be mounted on a flat surface, top-hat rail (to EN50 022 – 35 x 7.5; BS 5584; 35 x 27 x 7.3 DIN46277), or G-profile rail (to EN50 035 – G32; BS 5825; 32 DIN46277).

6.1.3 Insulating mounting block SMB7

An alternative to the IMB7, to reduce the overall height of the installation to 97mm. Mounts on a flat surface only.

6.1.4 Earth rail mounting bracket ERB7

For supporting and electrically connecting the earth rail to the busbar, it mounts over either type of mounting block. Made of 3 x 10mm tinplated brass, the ERB7 is supplied with one bolt-down fitting for the rail – enabling easy removal for adding extra ETM7 terminals – and one 16mm

terminal for making an earth connection.

6.1.5 Earth rail ERL7

This rail mounts the earth terminals that are used to earth incoming cables and screens and attaches to the mounting blocks via an ERB7 earth rail mounting bracket. It is available in 1-metre lengths and is made of 3 x 10mm nickel-plated brass.

6.1.6 Earth terminal ETM7

Suitable for mounting on ERL7 earth rail to earth incoming cables and screens, with up to 2.5 terminals per barrier width possible. Supplied

14.5

ø4.4

11.5

Figure 9: Insulating mounting block IMB7

Figure 10: Insulating mounting block SMB7

Figure 8: Earth busbar EBB7

Figure 11: Earth rail mounting bracket ERB7

Figure 12: Earth rail ERL7

Figure 13: Earth terminal ETM7

126

21.1

M4 x 20 fixing screw

M4 x 20

fixing screw

14.1

58 72

11.5 25

INM700-10 June 2005

in bags of 50.

6.1.7 Tagging strip TAG7

Provides tagging facilities for up to 64 barriers. Supplied in 1-metre

lengths, and complete with TGL7 label and six ‘clic’ rivets for securing purposes.

6.1.8 Tagging strip label TGL7

Additional labels for TAG7 tagging strip, available separately. Supplied in 0.5 metre lengths, in packs of 10.

6.1.9 Tagging strip seal TGS7

Secures TAG7 tagging strip and label to the installation, to prevent unauthorised removal and maintain barrier identification. Supplied in bags of ten.

6.1.10 ‘Take Care’ intrinsic safety labels

Warning labels bearing the words ‘Intrinsically Safe System – TAKE

CARE’ are available for attaching to enclosures or in areas where intrinsically safe systems and equipment are in use. Plastic labels with adhesive fronts (ISL7) for attaching to the insides of transparent enclosure lids, and metal labels with adhesive backs (ISL3) are

available.

6.1.11 Torque spanner TQS7

For tightening barrier mounting studs. The spanner is set to a torque of

2.3Nm (20Ib in.) and fitted with a 7mm A/F socket.

6.1.12 Surface mounting clips SMC7

These clips are used for mounting small numbers of barriers on flat surfaces where it is not convenient or possible to use busbars. Supplied in bags of ten; two clips needed per barrier.

6.1.13 DIN-rail mounting kit DRK700

An MTL700/700P Series barrier fitted with the DRK700, can be attached to standard, ‘T’ section 35mm DIN rail, alongside MTL7000 and MTL7700 Series products. See Figure 19.

6.1.14 Dummy barrier MTL799

This accessory allows for expansion when designing a system and is a convenient means of reserving a position, or terminating spare leads and screens. It is packed as a standard MTL700/700P Series barrier, with hazardous-area terminals 3 & 4 internally connected to the fixing studs. Non-hazardous (safe) area terminals 1 & 2 are not connected. See figure 26 (page14).

6.1.15 Mounting kits

Four mounting kits are available, the MK2 (2 barriers), MK5 (5 barriers), MK12 (12 barriers), and MK20 (20 barriers). Each kit provides facilities for mounting and earthing the barriers, connecting the IS earth cable, terminating earth screens and noting tagging information (except the MK2 kit). Assembly instructions are given in sections 6.4 and 6.5. See figures 22 and 23 (pages 12 and 13).

6.2 Constructing the installation

Installing MTL700/700P Series barriers is very simple. The barriers mount on standard earth busbar which is supported by insulating mounting blocks, themselves mounting on any flat surface or suitable DIN rail. In addition, an earth rail plus terminals is provided for terminating cable screens, and a tagging strip allows the barrier and its location to be identified.

Figure 20 shows how the accessories fit together to make up the installation, and should be referred to while carrying out the construction procedure.

6.2.1 Determine the number of barriers to be mounted on the busbar.

The maximum number is 25 between mountings, but a 1-metre length of busbar can accommodate up to 64 barriers. So for up to 25 barriers, cut a length of busbar with the required number of mounting positions, plus two extra for the mountings. For 26 to 50 barriers, three extra mounting positions are required. For 51 to 64 barriers, four extra positions are required.

6.2.2 Position the busbar on the fixing studs of the IMB7 or SMB7

mounting blocks. The blocks should face the same way and be located not more than 25 spaces apart.

Figure 14: Tagging strip TAG7

Figure 18: Surface mounting clips SMC7

Figure 19: DIN-rail mounting kit DRK700

Figure 15: Tagging strip seal TGS7

Figure 17: Torque spanner TQS7

Figure 16: ‘Take Care’ instrinsic safety label ISL3 or ISL7

140 (65*)

Intrinsically

Safe System

100 (40*)

TAKE CARE

MEASUREMENT TECHNOLOGY LTD

175

14.5

4.2

INM700-10 June 2005

6.2.3 Fit the ERB7 earth rail mounting brackets also onto each mount-

ing block’s studs, on top of the busbar, ensuring that the large terminals are on the hazardous-area side. Tighten the IMB7 or SMB7’s fixing nuts using the TQS7 torque spanner.

6.2.4 If SMB7 mounting blocks have been used, fix the whole

assembly to a flat surface using the two screws located in each block. Installations using IMB7s can be similarly mounted, or alternatively on top-hat or G-profile rail. For rail mounting, check that the swing nuts are turned out of the way, and locate the IMB7s on the rail. As the appropriate screws are tightened, the swing nuts pivot into position under the edges of the rail, thus securing the assembly. (The two angled screws are for Gprofile rail, and the two vertical screws for top-hat rail). It may be necessary to remove the surface mounting screws from the IMB7s to achieve a flush fitting onto the rail.

6.2.5 Mount the barriers on the busbar in the required positions,

tightening all fixing studs using the TQS7 torque spanner, or a torque wrench set to 2.3Nm (20 Ib.in.). Note that damage to the threads may occur if a higher torque than this is applied. Ensure all the barriers’ hazardous-area terminals face the hazardous-area side. Where barriers are mounted in rows on parallel busbars, the barriers in alternate rows should be reversed to keep the hazardous and non-hazardous (safe) area terminals apart. Also ensure that there is sufficient clearance to allow their removal and replacement, as shown in figure 21.

6.2.6 Slide the required number of ETM7 earth terminals onto the

ERL7 earth rail, and fit this assembly into the large terminals on the ERB7 brackets. Tighten these large terminals using a 10mm A/F spanner.

6.2.7 Complete the installation by fitting the tagging facilities. First,

take the 1-metre length of TAG7 tagging strip and remove the pack of four ‘clic’ rivets taped to the underside. Also, remove the clic rivets from both ends of the strip by pressing them out from the rear. The TGL7 tagging strip label can now be removed and, along with the TAG7 tagging strip, cut to length if necessary. After the TGL7 tagging strip label has been

marked with loop identification numbers etc., refit it into the TAG7 tagging strip and secure it by replacing one of the clic rivets. If the TAG7 has been cut to length, drill a 3.2mm diameter hole in the cut end, diagonally opposite the existing clic rivet (7.5mm along, 12.5mm in) to accommodate the tagging seal. Clip the TAG7 onto the installation, using the lugs located on the top of each mounting block. Finally, ‘seal’ the tagging information to the installation by fitting a TGS7 tagging strip seal through the hole drilled previously in the TAG7 tagging strip, and the vertical slot in the mounting block. The information on the TAG7 label and the barrier model numbers themselves can both be seen at the same time, thus making it easy

Figure 21: Recommended clearances for mounted barriers (shaded portions show areas swept by barrier during installation and removal)

Figure 20: Installation using the MTL700/700P

INM700-10 June 2005

6.3 Using SMC7 surface mounting clips

Insert one SMC7 clip into the slot in each end of the barrier, pushing well into place. The barrier can then be fixed to a flat surface using screws or bolts up to 4.2mm outside diameter (M4 or similar). See figure 26.

6.4 MK2 mounting kits

6.4.1 MK2 parts list

Part number Description Quantity

1 Mounting bracket 1 2 Insulating block 1 3 3.9 x 9.5 self-tapping screws 4 4 M4 washers 4 5 Terminal clamp (4mm) 3

6.4.2 MK2 kit assembly instructions a) Use the four self-tapping screws (3) and M4 washers (4) to attach

the mounting bracket (1) to the insulating block (2) through the four M4 holes.

b) The insulating block (2) is provided to keep the IS earth (termi-

nated on the mounting bracket (1)) separate from a structural earth but, if the mounting surface is insulated, then the insulating block may not be necessary.

c) Use the 4mm terminal clamps (5) to connect the IS earth and ter-

minating cable screens to the mounting bracket.

6.5 MK5, MK12 and MK20 mounting kits

6.5.1 MK5 parts list

Part number Description Quantity

1 DIN rail (156mm) 1 2 Earth busbar (99mm) 1 3 Earth rail mounting brackets 2 5 Insulating mounting block 2 6 Tag label assembly 1 7 Tagging strip seal 1 8 M4 Nyloc nuts 4 9 M4 washers 4 11 Terminal clamps (16mm) 3 12 Terminal clamps (4mm) 3

6.5.2 MK12 parts list

Part number Description Quantity

1 DIN rail (246mm) 1 2 Earth busbar (200.5mm) 1 3 Earth rail mounting brackets 2 4 Earth rail (215mm) 1 5 Insulating mounting block 2 6 Tag label assembly 1 7 Tagging strip seal 1 8 M4 Nyloc nuts 4 9 M4 washers 4 10 Earth rail clamp 2 11 Terminal clamps (16mm) 3 12 Terminal clamps (4mm) 6

6.5.3 MK20 parts list

Part number Description Quantity

1 DIN rail (388mm) 1 2 Earth busbar (316.5mm) 1 3 Earth rail mounting brackets 2 4 Earth rail (330mm) 1 5 Insulating mounting block 2 6 Tag label assembly 1 7 Tagging strip seal 1 8 M4 Nyloc nuts 4 9 M4 washers 4 10 Earth rail clamp 2 11 Terminal clamps (16mm) 3 12 Terminal clamps (4mm) 10

6.5.4 MK5, MK12 and MK20 kits assembly instructions

Note: The MK5 kit is NOT provided with an earth rail and earth rail clamps, so take care to follow the special instructions given in d) rather than c) if using this kit.

a) Locate the busbar (2) on the fixing studs of the insulating mounting

blocks (5), making sure both blocks face the same way.

b) Fit the earth rail mounting brackets (3) onto the studs of each mount-

ing block on top of the busbar, and secure using M4 washers (9) and Nyloc nuts (8). The longer ends lie in the safe area.

c) (MK12 and MK20 only). Fit the earth rail clamps (10) onto the

shorter protruding lengths of the earth rail mounting brackets (3). This is the hazardous side of the assembly. Slide the smaller (4mm) terminal clamps (12) onto the earth rail (4) and mount the earth rail onto the earth rail mounting brackets (3) with the earth rail clamps (10). Fit the larger (16mm) terminal clamps (11) onto the longer protruding lengths of the earth rail mounting brackets (3), two being mounted on one bracket and one on the other. These terminals are used for connecting the IS earth.

d) (MK5 only). Fit the smaller (4mm) terminal clamps (12) onto the

shorter protruding lengths of the earth rail mounting brackets (3) and the larger (16mm) terminal clamps (11) onto the longer protruding lengths. In both cases, two are mounted on one bracket and one on the other. The smaller terminal clamps serve the same purpose as the earth rail and clamps for the MK12 and MK20 while the function of the larger terminal clamps is the same for all three kits.

e) To mount the insulating mounting blocks (5), check that the swing

nuts forming part of each unit are turned away and locate the units on the DIN rail (1). Tighten the screws accessing the swing nuts to pivot them underneath the edge of the DIN rail, so securing the blocks to the rail.

f) Complete the installation by adding the tagging facilities. First,

remove the label to add identification then replace and secure with the clic rivet. Second, clip the tag label assembly (6) onto the installation with the lugs on top of each insulating mounting block (5). Third,’seal’ the tagging information to the installation by fitting the tagging strip seal (7) through the hole in the tagging strip and the vertical slot in the mounting block. The tagging strip can be unclipped from one side only and hinged open to provide access to the mounting studs and terminals of the barriers when required.

Figure 22: MK2 kit assembly diagram

INM700-10 June 2005

7 WIRING INSTALLATION

Before undertaking the installation of MTL700/700P Series barriers, section 4 of this manual should be read before commencing the instructions contained in this section. All instructions in this section apply to barriers mounted in MTL enclosures or as unenclosed systems. Figure 24 should be referred to for usage of earthing terminals in enclosures. For enclosures, all cables will need to be connected via suitable glands (not supplied), as described below.

7.1 Glanding cables into enclosures

7.1.1 MT2 and MT5

Two pre-drilled 20mm gland holes are provided in the base of each enclosure, fitted with push-in blanking plugs.

7.1.2 MT12

The enclosure has detachable top and bottom gland plates, for drilling by the user. This can be done with the gland plates in situ, or removed if preferred. To remove the gland plates, firmly press the plate retaining lip on the inside of the enclosure to release the front edge of the plate. Then, gently lever the plate retaining lip at the back of the enclosure to release the rear edge of the plate. Note that the embossed arrow on the inside of the gland plate always points towards the front of the enclosure when fitted, and then drill the gland holes in the required positions. The gland plates snap back into position.

7.1.3 MT20N

This enclosure has detachable top and bottom gland plates, for drilling by the user. This can be done with the gland plates in situ, or removed if preferred. To remove the gland plates, simply unbolt them from the enclosure.

7.2 Earthing the barriers

To ensure correct and safe operation of the barrier system, it is vitally important that the installation is earthed properly. All MTL700/700P Series barriers should be connected to a high-integrity earth via a copper conductor. The resistance of this conductor should not exceed 1Ω, although in order to increase safety and minimise interference, a resistance of 0.1W should be aimed for whenever possible. The crosssectional area of the conductor must be greater than 4mm2(12AWG).

Where the barriers are mounted on a busbar, the conductor should be connected to the 16mm2terminal on the ERB7 earth rail mounting bracket. Alternatively, the connection can be made directly to the busbar using a vibration-proof ring tag. For greater integrity, a duplicate earth connection should be made to the terminal on a second ERB7 bracket.

On MT Series enclosures, the earth connections should be made to the ERB7 brackets as described above (or to the 4mm

terminals in the case of the MT2), and fed into the enclosure via the non-hazardous (safe) area cable gland.

Although terminals 2 and 4 on 1-channel barriers are internally connected to the barrier earth studs, (MTL702, 705 and 706: terminal 4 only), they SHOULD NOT be used as a means of connecting the system to the high-integrity earth circuit.

To avoid the difficulty posed by the need to test the earth circuit periodically in accordance with the requirements of BS 5345, it is advisable to use two earth conductors for earthing the system, as shown in figure 25. It is then possible to connect a multimeter into the loop to measure the loop resistance without disturbing the circuit. In this case the resistance should not exceed 2Ω. This arrangement will also allow

DIN rail (item 1) Mounting centres hole diameters

MK5 140 4.5 nom. MK12 200 and 5.5 nom.

179 (choice)

MK20 357 5.5 nom

All dimensions in mm

Figure 23: MK5, MK12 and MK20 kit assembly diagram

Note: MK5 has no items

4 and 10. See 6.5.4.d

Non-hazardous (safe) area sideHazardous area side

INM700-10 June 2005

the circuit to be monitored continuously by a bonding integrity monitor such as the MTL2316, which gives warning if there is a significant increase in resistance, or if large currents are sensed. IS earth conductors should be identified by coloured insulating tape, preferably blue, wound around them at intervals along their length.

It is common practice (but not mandatory) to insulate IS earth busbars and associated conductors from the surrounding metalwork and plant earth cables. This minimises the possibility of the earth circuit being invaded by leakage or fault currents which, through common impedances, might interact adversely with this and other systems. It is far easier to design an insulated installation than to discover later that insulation is necessary, when disassembly and power removal will be unavoidable. MTL700/700P Series accessories IMB7 and SMB7 insulating mounting blocks are a convenient method of insulating busbars, as shown in figure

20. Further information about the earthing of IS systems is contained in BS 5345: Part 4: 1977, Section 3, Code 16.

If SCM7 surface mounting clips are used to mount a small number of barriers, the earth connections will have to be made directly to the barriers’ earth studs. Figure 26 shows a recommended method where the two earths are connected to different barriers, with the remaining studs all linked together. The earth conductors must have a minimum cross-sectional area of 4mm2. Hazardous-area cable screens can be connected to the earth studs, or terminal 3 and 4 of an MTL799 dummy barrier.

7.3 Connecting non-hazardous (safe) area cables to barriers

The non-hazardous (safe) area cables must be connected only to terminals 1 and 2 of MTL700/700P Series barriers. They should be segregated from hazardous-area cables and routed from the nonhazardous (safe) area equipment via the non-hazardous (safe) area loom, conduit or trunking. Care must be taken if standard barriers are to be connected to a non-hazardous (safe) area power supply. If the supply is connected the wrong way around, the barrier fuse will blow

and the unit will need replacing. (MTL702, 705, 706, 707, 707P and 708 overvolt-protected barriers cannot be damaged in this manner). For standard barriers, ensure also that the supply voltage does not exceed the working voltage (Vwkg) of the barriers as specified in section 3.2.

Do not connect barriers to non-hazardous (safe) area equipment that is supplied from, or contains, a source of potential with respect to earth that exceeds 250V rms or 250V dc under normal or fault conditions, unless specifically permitted to do so by the safety documentation. (Connection to non-hazardous (safe) area equipment fed from a threephase 440V neutral earthed supply is permissible).

All unused non-hazardous (safe) area cables should be secured safely to terminals 1 and 2 of an MTL799 dummy barrier, or by some other suitable method.

7.4 Connecting hazardous-area cables to barriers

The hazardous-area cables must be connected only to terminals 3 and 4 of MTL700/700P Series barriers. They should be segregated from non-hazardous (safe) area cables and routed to the hazardous-area equipment via the hazardous-area loom, conduit or trunking.

Before making any connections, ensure that all energy-storing devices (i.e. devices that are not classified as ‘simple apparatus’) used in the hazardous area are certified compatible with the barrier combination being used. Then check that the cables used for connecting the barriers to the hazardous-area equipment conform with the type of cables

specified in the safety documentation. Make sure that the maximum permitted cable parameters stipulated for the particular types of barrier in tables 9 to 12 (BASEEFA) or tables 13 to 22 (FM) are not exceeded. In general, cable parameters are unlikely to present problems except where cables longer that 500m are used for Group IIC applications.

Hazardous-area equipment and its interconnections should be isolated from earth to the extent that it is capable of withstanding a 500V isolation test, but such tests can only be undertaken when the area is gas free. Fortunately however, most circuits may be tested at low voltages by first disconnecting at the barrier any cable connected directly to earth or returned via a barrier with a nominal voltage of less than 10V. The resistance to earth of the non-hazardous (safe) area terminals can then be checked with a multimeter and should be greater than 100kΩ.

Note:

some hazardous-area instrumentation (e.g. pH and conductivity) is, by its nature, unable to withstand the 500V insulation test method mentioned above. Where this is the case, the system may alternatively comply with the installation requirements specified in IS sketch 121 (figure 27) and BS 5345, Part 4, 1977, Section 3, Code 16.

Hazardous-area earth returns and cable screens should be earthed via the ETM7 earth terminals mounted on the ERL7 earth rail (on the mounting bracket in the case of the MT2 enclosure). However, in the case of 1-channel barriers, earth returns and cable screens can be connected to terminal 4 of the barrier with which they are associated, because that terminal is internally connected to the earth studs.

All unused hazardous-area cables should be secured safely to terminals 3 and 4 of an MTL799 dummy barrier, or by some other suitable method.

Figure 26 shows the MTL799 used as a convenient technique for terminating screens and is another possible use.

Figure 26: Use of the MTL799 dummy barrier (also shows alternativemounting method using SMC7 clips

Figure 25: Earthing with two conductors

Figure 24: Usage of earthing terminals

4mm2 terminals

for earthing hazardous

area screens or earth

returns

16mm2 terminal for safe area

0V connections or power supply returns

Resistance meter or bonding integrity monitor

Loop resistance < 2W

terminals for

16mm

duplicated earth

connections

Local distribution transformet

Earthy terminals of dummy barrier used to terminate screens

Spare cores terminated

Nuts omitted for clarity

Wires to be 4mm cross-sectional area (CSA) minimum

in dummy barier MTL799

INM700-10 June 2005

Where the hazardous area equipment is connected to earth either directly or indirectly, and/or it will not withstand a 500V insulation test to ground, (e.g. strain-gauge bridges with low-voltage insulation, pH and conductivity measuring electrodes, bare and/or earthed thermocouples, some level detecting elements), the following apply:

1. Safety requirements

1.1 The pipe, vessel, or body of the hazardous-area apparatus and/or the adjacent metallic structure must be connected to the barrier busbar by a bonding conductor not less than 8mm2 cross-sectional area (CSA). With this size conductor the bonding conductor must not exceed 200m in length. If the bonding conductor is less than 100m the conductor need only be 4mm2in cross-sectional area.

1.2 Where bonding conductors are used, care should be taken to avoid invasion of other intrinsically-safe systems, which do not utilise bonding conductors, by elevation caused by any currents which may flow in the common earthing systems due to the presence of the bonding conductor. Where this possibility cannot be avoided, then the busbar on which the barriers are fitted should contain only barriers associated with bonded systems, and it should be earthed separately from other barrier busbars.

1.3 The hazardous-area equipment and/or adjacent metallic structure bond connections must be secure against vibration and corrosion. A terminal of the type used on Type ‘e’ equipment is the required solution.

1.4 The barrier busbar connections must provide adequate termination facilities for the bonding conductor and usual ‘earth return’, by the provision of separate Type ‘e’ terminals.

1.5 Where the barriers are located in Zone 2, the enclosure and the wiring to the non-hazardous (safe) area connections of the barrier must comply with the requirements of Type ‘N’ protection.

2. Operational requirements

2.1 This sketch shows the ‘0V’ rail of the non-hazardous (safe) area equipment returned to the barrier busbar by a separate insulated conductor, and the structural earths of the barrier enclosure and safe-area equipment returned separately to the neutral star point. This technique reduces interference problems, but is not essential for safety.

2.2 In general, the use of barriers in all measurement leads reduces the possibility of earth circulating currents creating measurement problems.

3. Neutral star point earth

3.1 Resistance to ‘terrestrial earth’ is determined by other regulations. It is NOT modified or determined by the intrinsic safety

requirements.

Hazardous area equipment incapable of withstanding insulation test

Zone 0, 1 or 2

Zone 2 or safe area

Non-hazardous (safe ) area

Local distribution transformer

Nonhazardous (safe) area

equipment

Bonding conductor

Less than 100 metres: 4mm

min. CSA

100 - 200 metres (max): 8mm2 min. CSA

Barriers

Enclosure

1W max.

Figure 27: Bonding practice where hazardous area equipment cannot meet required standards of insulation from earth

INM700-10 June 2005

7.5 Cable parameters for MTL700 Series – BASEEFA(ATEX) & FM

Table 9: Maximum cable parameters (gas group IIC)

(for notes 1, 2, and 3, see bottom of page)

702+ 1 Yes 0.110 2.39 47 0.17 2.2 0.782 706+ 1 Yes 0.083 3.05 56 0.12 4.0 0.65 707+ Both Yes 0.083 3.05 56 0.12 4.0 0.65 708+ 1 Yes 0.083 3.05 56 0.12 4.0 0.65

710 1 Yes 3.0 0.91 74 3.0 1.0 0.50

710P 1 Yes 3.0 0.38 44 4.89 0.22 0.75

715 1 Yes 0.580 1.45 66 0.7 1.4 0.56

715P 1 Yes 0.580 0.33 28 1.04 0.23 1.09

722 1 Yes 0.165 1.45 45 0.2 1.4 0.81

722P 1 Yes 0.165 0.30 32 0.33 0.53 1.18

728 1 Yes 0.083 3.05 56 0.12 4.0 0.65

728P 1 Yes 0.083 1.82 44 0.16 2.86 0.83

751ac 1 Yes 100 3.72 1464 1000 4.5 0.025

2 Yes 100 0.96 558 1000 1.2 0.05

No 100 3.72 732 1000 4.5 0.05

755ac 1 Yes 100 0.46 145 1000 0.4 0.225

2 Yes 100 0.13 69 150 0.1 0.45

No 40 0.41 73 150 0.1 0.45 3 No 40 0.125 48 – – 0.68 4 Yes 40 0.035 31.25 – – 0.92

No 40 0.06 42 – – 0.92

758 1 Yes 11.1 0.070 26 6.0 0.05 1.40

2 Yes 11.1 0.02 10 6.0 0.02 2.80

760ac 1 Yes 3.0 0.91 74 3.0 0.9 0.50

2 Yes 3.0 0.20 27 3.0 0.2 1.00

761ac 1 Yes 4.9 3.72 163 3.1 3.5 0.225

2 Yes 4.9 0.91 62 0.4 1.0 0.45

No 0.31 3.72 81 0.4 1.0 0.45 4 Yes 0.42 0.20 26.39 – – 0.90

No 0.42 0.37 37.78 – – 0.90 6 Yes 0.42 0.085 14.39 – – 1.35

No 0.42 0.13 18.67 – – 1.35

761Pac 2 Yes 0.31 56 306 0.43 14.4 0.115

764± 1 Yes 1.41 240 1000 1.5 200 0.036

2 Yes 1.41 61 360 1.0 60 0.072

764ac 1 Yes 1.41 240 1000 1.5 200 0.036

2 Yes 1.41 61 360 0.18 60 0.072

No 0.125 240 500 0.18 60 0.072

765ac 1 Yes 0.58 1.45 66 0.7 1.3 0.56

2 Yes 0.58 0.32 22 0.7 1.4 1.125

766ac 1 Yes 1.41 5.8 151 1.5 5.6 0.24

2 Yes 1.41 1.47 58 0.18 1.5 0.48

No 0.125 5.8 75 0.18 1.5 0.48

766Pac 2 Yes 1.41 0.34 29 0.22 0.20 0.942

767 1 Yes 0.58 1.45 66 0.7 1.7 0.56

2 Yes 0.58 0.32 22 0.5 0.4 1.125

768 1 Yes 0.165 1.45 45 0.2 1.7 0.81

772ac 1 Yes 0.165 6.77 89 0.2 6.0 0.404

2 Yes 0.165 1.45 34 0.2 1.8 0.808

778ac 1 Yes 0.083 16 107 0.12 14 0.327

2 Yes 0.083 3.05 42 0.12 4.2 0.654

779 1 Yes 0.083 3.05 56 0.12 4.0 0.65 786 1 or 2 Yes 0.083 – – 0.11 500 –

787 & 787S Both Yes 0.083 3.05 56 0.11 4.0 0.65

787SP 2 Yes 0.083 1.82 44 0.13 2.70 0.835

788 & 788R Both Yes 0.083 0.33 25 0.11 0.5 0.92

791 Both No 0.165 0.30 32 0.24 0.31

1.18

796 Both Yes 0.10 1.94 34 0.13 2.0 0.81

707P 2 Yes 0.65 5.65 127 0.45 6.21 1.19 729P 1 Yes 0.65 5.65 127 0.49 6.25 1.19

Number of

single channels

interconnected

within

hazardous area

Barrier

model

number

MTL

Earth

return

used?

Maximum permissible cable parameters

Capacitance

µF

Inductance

L/R ratio

µH/

ΩΩ

Capacitance

µF

Matched

power

(BASEEFA)

Inductance

BASEEFA (ATEX) (group IIC)

FM (groups A&B)

BASEEFA (group IIB)

FM (group C)

* L/R = 31µH/Ω

1x715P Ex92C2425 Yes 0.135 0.23 39.3 0.91 4x764ac 2 x 761ac channels Ex842125 Yes 0.2 0.24 11.6 1.01 2 x 764ac channels 2 x 766ac channels 4 x 761ac channels Ex842125 Yes 0.2 0.2 12.7 0.98 2 x 764ac channels 4x761Pac channels 2x766Pac channels Ex92C2424 Yes 0.18 0.17 18.4 1.17 2 x 764ac channels Ex842128 Yes 0.2 0.28 11 1.04 4 x 766ac channels 758 + 761ac Ex872392 Yes 0.42 0.013 10.5 3.27

4 x 764ac channels Ex842128 Yes 0.6 1.1 32.6 1.12 4 x 766ac channels 2 x 768 channels Ex842114 Yes 0.78 1.8 70 1.62 2 x 768 channels Ex842114 Yes 0.39 1.8 46.6 1.62 Any number of 786 channels 2 x 779 channels Ex842114 Yes 0.39 4.3 83 1.3 2 x 779 channels Ex842114 Yes 0.39 4.3 55.6 1.3 Any number of 786 channels

The tables give the maximum permitted cable parameters (including cable and load) for hazardous-area circuits in group IIC and IIB gases. However, the tables are by no means exhaustive and for full details of other safe combinations, consult either BASEEFA system certificates Ex832469, Ex92C2374 or Ex92C2376 or MTL. The MTL702 is covered by BASEEFA system certificate Ex842308, and the MTL706 by Ex872513. In practice cable parameters rarely present a problem, as all cables normally used for instrument interconnection have L/R ratios below 25µH/Ω and capacitance below 200pF per metre.

Note 1 If a ‘No’ value is not quoted for a barrier, use the ‘Yes’ value. Note 2 The maximum power that can be drawn from the barrier combination under fault conditions. Used for assessing the temperature classification of ‘simple’ hazardous-area apparatus. Note 3 Values for Groups IIA and IIB are given on certificates BAS01ATEX7202 and BAS01ATEX7203. For FM permitted combinations, refer to MTL document SCI-88 (via FM ref 1H8A1.AX).

BASEEFA

Maximum permissible cable parameters for group IIC (hydrogen)

System

combination

BASEEFA

system

Cert. No.

Capacitance µF

Earth

return used?

Inductance mH or L/R ratio µH/

ΩΩ

Matched

power

(BASEEFA)

BASEEFA

Maximum permissible cable parameters for group IIB (not safe for group IIC)

INM700-10 June 2005

7.6 Entity concept parameters for MTL700 Series – FM

Table 10: Entity concept parameters for 1-channel MTL700 barriers (figure 28)

Barrier Voc Isc Ca La

model no.

(MTL) (V) (mA) (µF) (mH)

702 25.11 125 0.17 2.2 705 28.1 93 0.12 4.0 706 28.1 93 0.12 4.0 708 28.1 93 0.12 4.0 710 10.03 189 3.0 1.0 715 15.06 146 0.7 1.4 722 22.08 146 0.2 1.4 728* 28.12 93 0.12 4.0

* One channel of an MTL779 can be used in place of an MTL728

Hazardous location equipment (see note 1 - after table 21))

2 1

3 4

Non-hazardous location devices V  250V max. (see note 2 - after table 21)

Ground (1W max)

1 - channel barrier

Note: one channel of an MTL779 may be used in place of an MTL728

1 - channel barriers

Non-hazardous location

Hazardous location Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Figure 28: 1–channel barrier connections

Figure 29 Figure 30 Barrier model No. Voc Isc Ca La Voc Isc Ca La MTL (V) (mA) (µF) (mH) (V) (mA) (µF) (mH)

751 1.92 89 1000 4.5 0.96 89 1000 4.5 755 5.92 296 1000 0.4 2.96 296 1000 0.4 758 ––––8.58216.00.05 760 10.03 97 3 3.5 10.3 194 3.0 0.9 761 18.08 99 0.40 3.5 9.04 99 3.1 3.5 764± 13.25 6 1 800 12.05 12 1.5 200 764ac 24.10 12 0.18 200 12.05 12 1.5 200 765 15.08 75.4 0.70 6 15.08 147 0.7 1.3 766 24.10 80.4 0.18 5.6 12.05 80 1.5 5.6 767 16.35 75.8 0.50 6 15.15 147 0.7 1.7 768 23.33 73.5 0.20 6 22.13 147 0.2 1.7 772 22.13 36.9 0.20 22 22.13 73 0.2 6 778 28.23 23.6 0.12 58 28.23 46 0.12 14 779 29.37 46.5 0.11 14 28.17 93 0.12 4 786 29.20 0 0.11 500 28.00 0 0.12 500 787 (28V ch) 29.74* 94* 0.10* 4* 28.54 94 0.11 4 787 (diode ch) ––––28.00 0 0.12 500 788, 788R (28V ch) 28.75* 82* 0.11* 5.6* 28.15 93 0.12 4 788, 788R (10V ch) ––––10.04 189 3.0 1 796 (26V ch) 27.30* 40* 0.13* 22* 26.10 86 0.14 4.7 796 (20V ch) ––––20.05 51.4 0.3 13

Table 11: Entity concept parameters for 2-channel MTL700 barriers with no ground return (figure 29) and separate ground returns for each channel (figure 30)

* Parameters when barrier channels are interconnected

Table 12: Entity concept parameters for 2-channel MTL700 barriers with optional ground return (figure 31)

Barrier Voc Isc Ca La

model no.

(MTL) (V) (mA) (µF) (mH)

707 28.1 93 0.12 4.0 758 8.1 1482 6.0 0.02 787S 28.7 93 0.11 4.0

Figure 29: 2–channel barrier connection with no ground return

Figure 30: 2–channel barrier connection with separate ground return

for each channel

Figure 31: 2–channel barrier connection with optional ground return

Hazardous location

Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Hazardous location equipment (see note 1 -on page

20)

Ground (1W max)

Non-hazardous (safe) location

2 - channel barriersno ground return

3 4

2 - channel barrier

Note

grounded shields or conduit.

Non-hazardous (safe) location devices V £ 250V max. (see note 2 - on page 20)

: No ground return permitted,nor

Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Hazardous location equipment (see note 1 -on page

20)

Hazardous location equipment (see note 1 -on page

20)

Hazardous location

Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Hazardous location equipment (see note 1 -on page

20)

Each channel with ground return

3 4

Ground (1W max)

Non-hazardous (safe) location

2 - channel barriers optional ground return

3 4

Optional

Non-hazardous (safe) location

2 - channel barrier

: Ground returns for each piece of hazardous

Note

location equipment must be run separately

Non-hazardous (safe) location

2 - channel barrier

Optional

Ground (1W max)

Non-hazardous (safe) location devices V £ 250V max. (see note 2 - on page 20)

INM700-10 June 2005

Table 13: Entity concept parameters for strain gauge bridge systems using MTL761/764 barriers (figure 32)

Group Ca La

(µF) (mH)

A & B 0.2 0.24

Figure 32: Strain gauge bridge combination using MTL761/764 barriers

Table 14: Entity concept parameters for strain gauge bridge systems using MTL761/764/766 barriers (figure 33)

Table 15: Entity parameters for Fieldbus barrier MTL791 and terminator FTB1 (figure 34)

Group Ca La

(µF) (mH)

A & B 0.2 0.2

C 0.6 0.6 D 1.6 1.6

Group Ca La L/R

(µF) (mH)

µµH/ΩΩ

A, B 0.24 0.31 31 C, E 0.74 2.97 121

D, F, G 1.99 5.50 242

Fieldbus Terminator FBT1

3 4

Non-hazardous (safe) location devices V £ 250V max. (see note 10 - on page 20)

Ground (1W max)

MTL791

Non-hazardous (safe) location

Hazardous location Class I Div 2 Groups A,B,C and D Class II Div 2 Groups F and G Class III, Div 2

Hazardous location equipment (see note 11 on page 20)

Figure 34: Fieldbus barrier system using MTL791 barrier and FBT1 terminator

Figure 33: Strain gauge bridge combination using MTL761/764/766 barriers

Barrier Groups Voc Isc Ca La

model No. (V) (mA) (µF) (mH)

MTL

710P+/- A, B 9.0 267 4.89 0.22 710P+/- C, E 9.0 267 14.6 2.23 710P+/- D, F, G 9.0 267 39.1 4.22

715P+ A, B 13.7 264 1.04 0.23 715P+ C, E 13.7 264 3.13 2.27 715P+ D, F, G 13.7 264 8.37 4.30

722P+ A, B 20.1 194 0.33 0.53 722P+ C, E 20.1 194 0.99 4.33 722P+ D, F, G 20.1 194 2.65 7.96

728P+ A, B 26.3 112 0.16 2.86

728+ C, E 26.3 112 0.49 12.0

728P+ D, F, G 26.3 112 1.32 23.8

729P+ C, E 26.3 160 0.49 6.25 729P+ D, F, G 26.3 160 1.32 11.6

7.8 Entity concept parameters for MTL700P Series – FM

Table 16: Entity concept parameters for single channel MTL700P barriers with

ground return (see figure 28 and notes 6 to 9)

Vt = 22V It = 233mA Po = 1.18W

Hazardous location

Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Hazardous location equipment (see note 1 -on page

20)

Hazardous location

Class I Div 1 Groups A,B,C,D Class II Div 1 Groups E,G Class III

Hazardous location equipment (see note 1 -on page

20)

3 4

Non-hazardous (safe) location

Strain gauge bridge combination

3 4

Ground (1W max)

Non-hazardous (safe) location

Strain gauge bridge combination

Ground (1W max)

MTL761 ac

MTL764 ac

MTL761 ac

MTL764 ac

MTL766 ac

Non-hazardous (safe) location devices V £ 250V max. (see note 2 - on page 20)

Table 17: Entity concept parameters for 2-channel MTL787SP barriers with diode return (figures 29, 30 and 31 and notes 6 to 9)

Table 18: Entity concept parameters for two-channel MTL700P barriers with an optional ground return (figure 31 and notes 6 to 9)

Table 19: Entity concept parameters for two-channel MTL700P barriers with separate ground returns (figure 30 and notes 6 to 9)

INM700-10 June 2005

Barrier Groups Voc Isc Each channel Each channel model No. (V) (mA) Ca (µF) La (mH) MTL

707P+ (return) C, E 14.1 0 2.85 1000 707P+ (return) D, F, G 14.1 0 7.62 1000 707P+ (signal) C, E 26.4 160 0.49 6.21 707P+ (signal) D, F, G 26.4 160 1.31 11.5

761Pac A, B 9.0 25 4.89 54.8 761Pac C, E 9.0 25 14.6 194.0 761Pac D, F, G 9.0 25 39.1 475.0

766Pac A, B 11.5 149 1.87 1.25 766Pac C, E 11.5 149 5.63 7.16 766Pac D, F, G 11.5 149 15.0 13.4

Figure 29 Figure 30 Figure 31

Model

No. Groups Voc Isc Ca La Voc Isc Ca La Voc Isc Ca La

(MTL) (V) (mA) (µF) (mH) (V) (mA) (µF) (mH) (V) (mA) (µF) (mH)

787SP A, B 28.9 115 0.13 2.70 25.9 110 0.17 2.93 28.9 115 0.13 2.70

(28V ch) C, E 28.9 115 0.39 11.52 25.9 110 0.51 12.3 28.9 115 0.39 11.52

D, F, G 28.9 115 1.06 22.57 25.9 110 1.38 24.3 28.9 115 1.06 22.57

787SP A, B – – – – 25.9 0 0.17 1000 – – – –

(diode ch) C, E – – – – 25.9 0 0.51 1000 – – – –

D, F, G – – – – 25.9 0 1.38 1000 – – – –

Barrier Groups Voc Isc Ca La

model No. (V) (mA) (µF) (mH)

MTL

707P+ C, E 27.4 160 0.45 6.21 707P+ D, F, G 27.4 160 1.20 11.5

761Pac A, B 18.0 50 0.43 14.4 761Pac C, E 18.0 50 1.29 53.0 761Pac D, F, G 18.0 50 3.46 119.0

766Pac A, B 23.0 297 0.22 0.20 766Pac C, E 23.0 297 0.66 1.72 766Pac D, F, G 23.0 297 1.77 3.39

Note 1: The hazardous-location-mounted equipment may be switches or ther-

mocouples. Other apparatus such as RTDs, LEDs, non-inductive resistors, (and strain-gauge load cells for the systems shown in figures 32 and 33), may be used if the auto-ignition temperature of the hazardous location is greater than T4 (275°F, 135°C). For the systems shown in figures 28, 29 and 30, certified devices with the correct entity concept parameters can also be used.

Note 2: The non-hazardous location or control-room mounted equipment

should not use nor generate more than 250V rms.

Note 3: For guidance on the installation see ANSI/SA RP 12.6. Note 4: Five MTL700 Series barriers are approved for installation in Group F:

MTL705, 707, 708, 787S and 758. All MTL700P Series barriers are approved for Group F.

Note 5: Full details of all approved combinations are available on MTL

drawing No. SCI-88

Notes 6 to 9 inclusive relate to tables 16 to 19 inclusive Note 6: The barriers are associated apparatus and, when mounted in an

appropriate enclosure can be installed in the following areas: a) Non-hazardous locations b) Class 1, Division 2, Groups A, B, C, and D hazardous locations c) Class II, Division 2, Groups F and G hazardous locations d) Class III, Division 2 hazardous locations

Note 7: Barriers must be installed in enclosures meeting the requirements of

ANSI/ISA–S82

Note 8: Use Factory Mutual Research Corporation approved dust-tight enclosures

appropriate for environmental protection for the following locations:– a) Class II, Division 2, Groups F and G hazardous locations b) Class III, Division 2 hazardous locations

Note 9: For installation guidance see ANSI/ISA 12.6 and the National

Electrical Code. See also Installation drawing SCI–326

Notes 10 to 14 inclusive relate to table 15 Note 10: The non-hazardous (safe) location equipment must not generate or

use voltages in excess of 250V rms. or dc

Note 11: The hazardous location equipment. Any number of FMRC approved

devices which meet the power and entity parameter requirements below may be connected to the Fieldbus:a) All device's electronic circuitry which interface directly to the fieldbus must be powered from fieldbus power. Other power sources in the devices (if any) must be galvanically isolated from the fieldbus power. b) Vmax of all devices must be equal to or greater than 22V. c) Imax of all devices must be equal to or greater than 233mA. d) Pmax of all devices must be equal to or greater than 1.18W. e) The sum of all devices unprotected input capacitance Ci, plus the cable capacitance must be equal to or less than Ca for the applicable Gas Group in Table 15. f) The sum of all devices unprotected input inductance Li, plus the cable inductance must be equal to or less than La for the applicable Gas Group in Table 15.

Note 12: For guidance on installation see ANSI/ISA RP12.6 and the USA

National Electric Code.

Note 13: The barrier must be installed in enclosures meeting the requirements

of ANSI/ISA – S82 and the USA National Electric Code.

Note 14: Use FMRC – approved, or NRTL – listed, dust – ignition proof enclo-

sures appropriate for environmental protection in Class II, Division 2, Groups F and G, and Class III Hazardous Locations.

7.9 Final check

After completing the installation, each item contained in the checklist (table 8) should again be checked out by a competent person, preferably someone who has not been involved in the work.

8 MAINTENANCE

Since the MTL700/700P Series barriers are encapsulated they cannot be repaired, but provided they are connected correctly to the circuits they are intended to protect, and provided those circuits are not themselves defective, barrier defects are unlikely to occur. For these reasons, servicing of barrier installations consists principally of the routine inspection and earth testing described in this section.

If replacements do have to be fitted however it is worth checking, in the case of barriers connected directly to power supplies, if one of the new overvolt-protected models can be substituted. These models can tolerate supply voltages up to 35V dc without blowing their fuses, and can therefore eliminate the problem of poorly regulated supplies. Further information about the maintenance of barrier installations is given in BS 5345: Part 4: 1977, Section 4.

8.1 Routine inspection

At intervals of not more than two years (more frequently for particular environments), visually check the barrier installation to check the following points.

When undertaking these checks, personnel should comply with all the regulations relating to the safety of the plant and personnel. Great care must be taken to prevent any direct interconnection between hazardous and non-hazardous (safe) area circuits. The instructions given in section 4 of this manual should be observed at all times.

INM700-10 June 2005

8.1.1 Barriers should be of the types and polarities specified in the

safety documentation.

8.1.2 The barriers should be attached securely to the earth busbar,

thus making a good connection to the IS earth. Use a TQS7 torque spanner or other suitable wrench to check that each barrier's two ‘Nyloc’ nuts are tightened to a torque of 2.3Nm (20 lb.in.).

8.1.3 There should be no signs of damage or corrosion to the bar-

riers or the IS earthing system.

8.1.4 All connections should be properly made, and the tightness

of the hazardous and non-hazardous (safe) area terminals on the barriers checked.

8.1.5 Interconnecting cables should be of the type and rating spec-

ified in the safety documentation, and not frayed or otherwise damaged.

8.1.6 All earth returns and cable screens from the hazardous area

should be connected to earth via an earth rail and terminals.

8.1.7 Visually examine the earth conductors and ensure that they

are not damaged in any way, and that their terminations are secure and free from corrosion.

8.1.8 Using a low voltage, low-current test meter (i.e. a meter

whose output does not exceed 3V and 50mA), measure the resistance between the earth busbar and the neutral star point of the supply and ensure that it does not exceed 1W. Record the reading. A consistent reading repeated over a long period of time is indicative that the earth return is sound and likely to remain so. If two earth conductors are used as described in section 7.2, the loop resistance should be measured as described in that section. The reading obtained should not exceed 2Ω.

Important note: do not attempt to perform a high-current earth resistance test unless it is confirmed by the authority in charge of the plant that the plant is gas free.

9 FAULT-FINDING

Most barrier-protected systems are relatively simple and can be checked easily for operation. However, fault-finding procedures can be undertaken only after notifying all personnel concerned with plant safety and ascertaining that it is safe to proceed.

While it is not possible to describe fault-finding procedures for every type of barrier-protected circuit, there are several guidelines that can help to speed up the process.

The fault-finding procedures described in this section assume the use of a modern digital multimeter as this is the meter most commonly used. However, other test meters can be used provided that their characteristics when measuring silicon diodes are known.

If a diode chain is involved when testing a barrier, it is useful to remember that many modern digital multimeters cater for such circuits by the provision of a diode test function. These meters usually pass 1mA through the diode and measure the voltage across it. When measuring more than two diode drops in series it is worth noting that the full scale range of some multimeters is only 2V on the diode test range. Therefore with three or more diode drops it is possible that the meter may indicate over-range and any voltage drop of more than 4V has been indicated in the test tables (this section and section 11) as infinity.

Zener diodes and ordinary silicon diodes have a typical forward voltage drop of approximately 0.6V per diode. Diode return paths with schottky diodes have a typical voltage drop of <0.3V for each diode in the chain, e.g. MTL787S and 787SP.

Figure 35 shows a typical switch-status transfer circuit protected by an MTL787S+ barrier, which can be used to illustrate some of the faultfinding techniques discussed in this section. To determine the serviceability of barriers, proceed as described in the remainder of this section, but whenever possible always check barriers by working on the non-hazardous (safe) area terminals and the circuits connected directly to them.

9.1 Power supply check

Check that the power supply is available to the barrier circuit and that the voltage across the supply and with respect to earth is correct. For example, referring to figure 35, the presence of 24V on terminal 1 and 12V on terminal 2 when the hazardous-area switch is closed confirms the serviceability of almost the complete circuit.

9.2 Barrier resistance test (not MTL702, 705, 706, 707, 707P and 708)

If testing a barrier in situ, refer to figure 35 and proceed as follows:

9.2.1 Disconnect the hazardous-area cables from the barrier, termi-

nals 3 and 4, and connect the cables to earth via the earth rail or some other means, or alternatively insulate them completely.

9.2.2 Disconnect the non-hazardous (safe) area cables, terminals 1

and 2, and insulate them completely to prevent them from shorting together, to other cables or earth. Be careful when handling non-hazardous (safe) area cables; the relay contacts in figure 35 for example could be carrying mains voltage.

9.2.3 Measure the end-to-end resistance of the barrier by connect-

ing a digital multimeter (set to a suitable ohms range) between terminal 1 and 3. The reading should be slightly less than the maximum end-to-end resistance quoted in section 3.2, or approximately 10 to 20% higher than the figure specified in the safety description. For the MTL787S+ the reading should be in the range 317 to 340Ω.

9.2.4 Check the serviceability of the diode-return channel by select-

ing the diode test function on the test meter and connect between terminal 4 (+ve) and 2 (–ve). This will measure the forward voltage drop of the MTL787S’s three Schottky diodes in the chain, and a reading of less than 0.9V should be expected. Then connect between terminal 2 (+ve) and 4 (–ve) for a reading of × for the reverse voltage drop.

9.2.5 Tests 9.2.3 and 9.2.4 confirm the continuity of both channels

of the barrier. If either channel is open-circuit it is most likely that the fuse has blown, in which case the non-hazardous (safe) area circuit should be investigated. If this is not the case and the fault has not been found, then carry out the tests in sections 9.3 and 9.4, and if a fault is still not found, remove the barrier for bench testing as follows:

9.2.6 Remove the suspect barrier from the equipment and take it to

a suitable area where it can be tested in accordance with section 11 Barrier tests. If the barrier is found to be defective, fit a new one of the appropriate model number.

Caution: After the removal of the barrier, ensure the safe-area and hazardous-area cables disconnected under 9.2.1 and 9.2.2 are either connected to an MTL799 dummy barrier or insulated completely.

9.3 Earth faults

Most intrinsically safe circuits are isolated from earth in the hazardous area. If it is suspected that a system earth fault exists, proceed as follows:

Hazardous area

Non-hazardous (safe) area

340W

30mA

12V

400W 12V relay

24V

High-integrity earth

Figure 35: Switch status transfer circuit using MTL787+

INM700-10 June 2005

9.3.1 Disconnect the hazardous and non-hazardous (safe) area

cables from the barrier terminals and either temporarily insulate them, or secure them safely to the appropriate terminals of an MTL799 dummy barrier.

9.3.2 For the barrier shown in figure 35 the readings shown in

table 20 should be obtained when connecting a test meter with the diode test function selected.

9.3.3 In the case of the circuit shown in figure 35, with the haz-

ardous-area cables connected to the terminals, and the test meter connected between terminals 1 (+ve) and 2 (–ve) a reading of × will be obtained if the switch is open and a reading of approximately 1.2V if the switch is closed, and no earth faults are present. To check if either of the hazardous-area cables is shorted to earth, connect the test meter as in table 21 which shows the readings that will indicate a fault to earth.

Table 20: Barrier earth fault tests with hazardous and non-hazardous (safe) area cables disconnected

Table 21: Barrier earth fault tests with hazardous and non-hazardous (safe) area cables connected

9.4 Faults between barrier channels

If it is suspected that faults exist between the channels of a 2-channel barrier, proceed as follows: (Note that these tests are not applicable to MTL751 or 755 barriers).

9.4.1 Disconnect the hazardous and non-hazardous (safe) area

cables from the barrier terminals and either temporarily insulate them, or secure them safely to the appropriate terminals of an MTL799 dummy barrier.

9.4.2 With a digital multimeter (set to diode test), check that there

is an open circuit between the two channels of the barrier (terminal 1 to terminal 2), and in at least one direction between the earth studs and terminal 1, and the earth studs and terminal 2.

10 THERMOCOUPLE AND RTD TESTS

10.1 Thermocouple circuit testing

Thermocouple test and calibration equipment is not usually certified intrinsically safe and therefore requires special authorisation before it can be used for testing or calibrating thermocouple circuits in hazardous areas. To overcome this problem the thermocouple circuits can be protected by using an MTL760 barrier as shown in figure 36. The barrier allows the thermocouple output to be measured without the need to get special authorisation to use the thermocouple test equipment.

As it is seldom possible to accurately measure the temperatures of thermocouples located in hazardous areas, a safe means is required of adjusting the calibration tables to compensate for the plant temperature. This can be achieved by disconnecting the compensating cables from the thermocouple, shorting them together, and then measuring the temperature of the shorting point.

10.2 Resistance thermometer detector circuit testing

Resistance thermometer detector (RTD) circuits can be tested by disconnecting the measuring leads from the RTD head in the hazardous area and connecting them to a resistance box. Sometimes it is more convenient to connect the resistance box in the non-hazardous (safe) area, for instance at point xx as shown in figure 37. However, in this case the RTD must be shorted out, or allowance must be made for its temperature. The effect of a negative temperature change can be simulated by connecting the resistance box in the measurement lead at point yy. The advantage of connecting the resistance box at the RTD head is that any leakage can also be determined by connecting the resistance box at point yy.

11 BARRIER TESTS

Note: There is no requirement for barriers to be subjected to routine

testing if they are in normal use.

The tests given in this section have been included to enable users to carry out additional tests to those given in section 8 if they suspect the performance of the barriers. Barriers which pass these tests satisfactorily are not likely to incur an unacceptable level of risk or cause a circuit malfunction.

From tables 26 to 33 it can be seen that there are two types of test: a simple test using a digital multimeter to test barriers without the need of having to remove them from the earth busbar, and a more comprehensive bench test using a constant current source to establish the breakdown characteristics of barriers.

BASEEFA certification requirements concentrate on high-current tests, but in many ways the leakage current tests given in this section are a more satisfactory method of testing suspect diodes. If a complete functional check of a barrier is required, then the multimeter tests and constant current tests described in section 10.1 and 10.2 should be undertaken. However, for most purposes the multimeter tests alone will suffice.

The MTL702, 705, 706, 707, 707P, and 708 cannot be tested in the same manner as ordinary 700 Series barriers; separate tests for these models are detailed in sections 11.3 to 11.6.

Positive lead Negative lead Test meter

on terminal: on terminal: reading:

1 Earth studs

∞

Earth studs 1 1.2V

2 Earth studs

∞

Earth studs 2 1.2V

12∞ 21∞

Positive lead Negative lead Test meter Cable fault

on terminal: on terminal: reading: from terminal:

1 Earth studs 0V 3 to earth

Earth studs 2 0.9V 4 to earth

3 4

High integrity earth

MTL755

Compensating cable

Non-hazardous (safe) area

Hazardous area

Non-hazardous (safe) area equipment

Callibration equipment

21 21

3 4

MTL755

Bridge supply

Variable resistance

Measurement

High integrity earth

Non-hazardous (safe) area

Hazardous area

Non-hazardous (safe) area equipment

Figure 37: Calibrating an RTD barrier circuit

Figure 36: Calibrating a thermocouple barrier circuit

INM700-10 June 2005

11.1 Multimeter tests

The use of a digital multimeter for testing barriers is described in section

9. The section 11 tables assume that the multimeter is selected to a suitable ohms range for the end-to-end resistance tests (except for diode return channels) and for the continuity tests, and that the multimeter diode test function is used for the diode tests, channel isolation tests and for the end-to-end resistance tests for diode return channels.

11.2 Constant-current tests

For these tests a constant-current generator is required. The generator must be capable of supplying 10µA, 20mA and 40mA currents from a 30V source. Ideally, a purpose-built current generator should be used, but a conventional laboratory power supply can be used as shown in figure 38. The current is measured on one multimeter and trimmed by adjusting the output voltage of the power supply indicated on a second multimeter. When using a constant-current generator for testing MTL700 Series barriers, the following points should be noted:

11.2.1The current should be limited to 50mA to avoid damaging the

barriers.

11.2.2The accuracy of the current is not critical and can therefore

vary by ±5%.

11.2.3The test leads must be connected securely to the barrier ter-

minals.

11.2.4The use of a high resistance in series with the barrier will give

more stable results and make it easier to set the required current.

11.3 Tests for the MTL702

Comprehensive testing requires specialised equipment, however, an effective test which will confirm whether the unit is operating correctly is shown in figure 39. The two ammeters used should be able to measure a signal of between 4 and 20mA with fairly good accuracy. Connect them as shown initially in the lead to terminal 3, and note if any error is present between the two readings. Then, move one of the meters to the terminal 2 lead (ensuring correct polarity) and check that the readings on the two meters are approximately equal.

11.4 Tests for the MTL705 and 706

Owing to the nature of these units, comprehensive testing requires specialised equipment, beyond the scope of on-site checks. However, an effective test which will confirm whether the units are operating correctly is shown in figure 40. Connected in this manner, ammeter 1 measures the transmitter simulator current of between 4 and 20mA flowing from terminal 4 and the safe-area load current flowing to terminal 4 simultaneously. Since these two currents are equal and opposite, the resultant reading on the ammeter should be virtually zero. Ammeter 2 is used to verify the presence of the 4 to 20mA transmitter signal.

11.5 Tests for the MTL707 and 707P

Since these units incorporate a built-in protection circuit, they have to be tested in a different manner to an ordinary shunt-diode barrier. Referring to figure 41, set the transmitter simulator to various currents in the range 4 to 20mA and check that the ammeter reads approximately the same value. Then, set the simulator to 20mA, checking the voltage between terminals 1 and 2 (<9V for the MTL707 and <4.3V for the MTL707P), and between terminals 2 and 4 (<3.1V for the MTL707 and <1.9V for the MTL707P).

11.6 Tests for the MTL708

This unit, of similar design to the MTL707, is tested in the same manner. Referring to figure 41, set the transmitter simulator to 20mA and check that the voltage between terminals 1 and 3 is less than 8.9V.

11.7 Test tables

These tables describe the tests for models MTL710 to 796 inclusive. The figures adjacent to the diode symbols indicate the number of forward-biased diodes used in the barrier chain. Using a multimeter diode test function and referring to the diode voltage drop figures given in section 9 (approximately 0.6V for each Zener diode and 0.3V for each Schottky diode) the expected reading across the diode chain can be determined.

Digital

multimeter

(voltage)

Digital

multimeter

(current)

To barrier on test

2 -channel laboratory power supply

0-30V

variable

(Current limited to 50mA)

0-30V

variable

Changeover

switch

3MW

1.5kW

750W

Current selector

10µA

20mA

40mA

+

Figure 38: Calibrating a thermocouple barrier circuit

Figure 39: MTL702 test circuit

Figure 40: MTL705 and706 test circuit

Figure 41: MTL707 and 707P test circuit

Figure 42: MTL708 test circuit

4-20mA

Transmitter simulator

250W

+20 to 35V dc

4-20mA

Transmitter simulator

250W

+20 to 35V dc

4-20mA

Transmitter simulator

250W

+20 to 35V dc

20mA

Transmitter simulator

+20 to 35V dc

INM700-10 June 2005

Min Max Min Max Min Max

710 10V 50Ω 67Ω 85Ω

∞ x 1 ✓ 6.0V 9.6V 6.6V 10.0V

710P 10V 33Ω 38Ω 42Ω ∞ x 1 ✓ 8.0V 9.0V 8.2V 9.5V

715 15V 100Ω 113Ω 155Ω

∞

x 1 ✓ 12.0V 14.2V 12.4V 14.9V

715P 15V 50Ω 56Ω 60Ω ∞ x 1 ✓ 12.5V 13.4V 12.7V* 3.9V*

722 22V 150Ω 167Ω 185Ω

∞

x 2 ✓ 19.0V 20.9V 19.8V 21.3V

722P 22V 101Ω 112Ω 121Ω ∞ x 2 ✓ 18.5V 20.0V 18.6V 20.3V

728 28V 300Ω 317Ω 340Ω

∞ x 2 ✓ 25.5V 26.5V 26.1V 26.9V

728P 28V 234Ω 240Ω 253Ω

∞ x 3 ✓ 24.5V 25.7V 24.7V 26.0V

729P 28V 164Ω 173Ω 184Ω

∞ x 3 ✓ 24.5V 25.7V 24.7V 26.0V

Min Max Min Max Min Max

758 7.5V 10Ω 15Ω 18Ω

∞ x 1 ∞ 6.0V 6.9V 6.5V 7.3V

764 12V 1KΩ 1.0kΩ 1.1kΩ ∞ x 1 ∞ 10.0V 11.4V 10.4V 11.8V

767 15V 100Ω 113Ω 155Ω ∞ x 1 ∞ 12.0V 13.9V 12.4V 14.5V

768 22V 150Ω 167Ω 185Ω ∞ x 2 ∞ 19.0V 20.7V 19.8V 21.1V

779 28V 300Ω 317Ω 340Ω ∞ x 2 ∞ 25.5V 26.3V 26.1V 26.7V

26V 300Ω 317Ω 340Ω ∞ x 2 ∞ 23.5V 24.4V 24.1V 24.8V

796

20V 390Ω 407Ω 435Ω ∞ x 2 ∞ 17.5V 18.8V 18.3V 19.2V

28V 300Ω 317Ω 340Ω ∞ x 2 ∞ 25.5V 26.4V 26.1V 26.8V

788

10V 50Ω 67Ω 85Ω ∞ x 2 ∞ 6.0V 9.5V 6.6V 9.9V

28V 300Ω 317Ω 340Ω

∞ x 2 ∞ 25.5V 26.4V 26.1V 26.8V

788R

10V 50Ω 67Ω 85Ω 0.33V 0.33V x 2 +0.33V 0V 0V 6.2V 6.8V

Table 22: Tests for 1-channel positive and negative Zener diode barriers

(For negative polarity barriers the same values apply, but the multimeter polarity and test leads must be reversed)

* Voltages obtained when applying a 40mA constant current

Table 23: Tests for 2-channel positive and negative Zener diode barriers

These barriers have similar properties to the 1-channel barriers detailed in table 22. The table gives details for testing positive barriers. For negative polarity barriers the same values apply, but the multimeter and supply leads must be reversed.

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

Safety

descrip-

tion

MTL

model

no.

Connect

+ve lead to

terminal 1 & –ve lead to term’l 2

Connect

–ve lead to

terminal 1

& +ve lead

to term’l 2

Check for continuity

between

term’ls 2 & 4

to earth studs

Continuity

test

Voltages obtained when

applying constant current

to terminal 1 (+ve) and

earth studs (–ve)

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

and then

between

2 and 4

Safety

description

MTL

model

no.

Connect –ve lead to earth studs & +ve lead to terminal

1 & then 2

Connect

+ve lead to

earth studs & –ve lead to terminal 1 & then 2

Connect

between

term’ls 1 & 2

(both

polarities)

Channel isolation

test

Voltage obtained when

applying constant current

to terminal 1 (+ve) and

then terminal 2 (+ve)

& earth studs (–ve)

(26V: MTL796)

(20V: MTL796)

INM700-10 June 2005

Min Max Min Max Min Max

710 10V 50Ω 67Ω 85Ω

∞ ✓ 6.0V 9.5V 6.9V 10.2V

728 28V 300Ω 317Ω 340Ω ∞ ✓ 24.5V 26.5V 25.7V 27.5V

Table 24: Tests for 1-channel ac Zener diode barriers

Owing to the symmetry of these barriers, measurements should be made with the current flowing in both directions.

Table 25: Tests for 2-channel ac Zener diode barriers

Owing to the symmetry of these barriers, measurements should be made with the current flowing in both directions.

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

Safety

descrip-

tion

MTL

model

no.

Check for continuity

between

term’ls 2 & 4

to earth studs

Voltages obtained when

applying constant current

to terminal 1 and

earth studs (both polarities)

Connect

between

terminals 1

& 2 (both polarities)

Min Max Min Max Min Max

761 9V 90Ω 102Ω 145Ω

∞∞6.0V 8.5V 6.9V 9.5V

761P 9V 350Ω 367Ω 384Ω ∞∞7.0V 8.7V 7.1V 9.0V

764 12V 1.0kΩ 1.0kΩ 1.1kΩ ∞∞10.0V 11.4V 10.7V 12.1V

766 12V 150Ω 165Ω 185Ω

∞∞10.0V 11.4V 10.7V 12.1V

766P 12V 75Ω 85Ω 93Ω

∞∞9.8V 11.1V 9.9V 11.4V

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

and then

between

2 and 4

Connect

between

earth studs

& terminal 1,

and then

terminal 2

(both polarities)

Safety

descrip-

tion

MTL

model

no.

Voltages obtained when

applying constant current

to terminal 1 and

earth studs (both polarities)

Connect

between

terminals 1

& 2 (both polarities)

Channel isolation

test

INM700-10 June 2005

Min Max Min Max Min Max

751 1V 10Ω 14Ω 20Ω x 1 x 2 0.3V 0.6V 0.6V 1.0V

755 3V 10Ω 17Ω 19Ω x 3 x 6 0.9V 1.8V 1.8V 2.8V

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

and then

between

2 and 4

Connect

between

earth studs

& terminal 1,

and then

terminal 2

(both polarities)

Safety

descrip-

tion

MTL

model

no.

Voltages obtained when

applying constant current

between earth studs and

terminal 1, and earth

studs and terminal 2

(both polarities)

Connect

between

terminals 1

& 2 (both polarities)

Channel isolation

test

Table 26: Tests for forward-diode barriers

These barriers use forward-connected diodes as voltage limiters. They are used for ac signals.

Min Max Min Max Min Max

760 10V 50Ω 67Ω 85Ω

∞∞6.0V 9.4V 6.9V 10.1V

765 15V 100Ω 117Ω 135Ω ∞∞12.0V 14.0V 12.7V 14.7V

772 22V 300Ω 317Ω 340Ω ∞∞ 18.0V 20.2V 19.4V 21.2V

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

terminals

1 and 3

and then

between

2 and 4

Connect

between

earth studs

& terminal 1,

and then

terminal 2

(both polarities)

Safety

descrip-

tion

MTL

model

no.

Voltages obtained when

applying constant current

between earth studs and

terminal 1, and earth

studs and terminal 2

(both polarities)

Connect

between

terminals 1

& 2 (both polarities)

Channel isolation

test

Table 27: Tests for star-connected ac Zener diode barriers

Like positive and negative barriers, these barriers are symmetrical and should therefore be tested with the current flowing in both directions.

INM700-10 June 2005

Min Max Min Max

786 28V(diode) ∞ x 3 ∞ x 2 ∞ 25.5V 28.0V 26.1V 28.4V

28V 300W 317Ω to 317Ω to

∞ x 2 ∞ 25.5V 26.3V 26.1V 26.7V

340Ω 340Ω

787

28V(diode)

∞ x 3 ∞∞25.5V 28.0V 26.1V 28.4V

28V 300Ω 317Ω to 317Ω to

∞ x 2 ∞ 25.5V 26.3V 26.1V 26.7V

340Ω 340Ω

787S

28V(diode)

∞ x 3 ∞ x 2 ∞ 24.5V 25.7V 24.7V 26.1V

Schottky

28V 234Ω 240Ω to 240Ω to

∞ x 2 ∞ 24.5V 25.7V 24.7V 26.1V

257Ω 257Ω

787SP

28V(diode)

∞ x 3 ∞ x 2 ∞ 24.5V 25.7V 24.7V 26.1V

Schottky

Barrier data

Basic circuit

Connect

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

+ve to 1

–ve to 2

then

+ve to 3

–ve to 4

–ve to 1

+ve to 2

then

–ve to 3

+ve to 4

Connect +ve lead to earth studs

& –ve lead to term’l 1

& then 2

Connect

–ve lead to earth studs & +ve lead

to term’l 1

& then 2

Safety

descrip-

tion

MTL

model

no.

Voltages obtained when

applying constant current

between earth studs and

terminal 1, and earth

studs and terminal 2

(both polarities)

Connect

between

terminals 1

& 2 (both

polarities)

Channel

isolation

test

Min Max Min Max Min Max

11V 51Ω 59Ω 63Ω ∞ x 1 10.0V 10.9V 10.1V 11.1V

791

∞ x 2

-11V 51Ω 59Ω 63Ω x 1

∞ 10.0V 10.9V 10.1V 11.1V

Barrier data

Basic circuit

Multimeter tests

Constant current

tests

End-to-end

resistance

test

Diode test

10µµA 20mA

Connect

between

term’ls 1 & 3

and then between

2 and 4

Connect

+ve lead

to earth

studs &

–ve lead

to 1 & then 2

Connect

–ve lead

to earth studs &

+ve lead

to 1 & then 2

Safety

descrip-

tion

MTL

model

no.

Voltages obtained when

applying constant current

to terminals 1(+ve), and

then terminals 2 (–ve)

and earth studs

Connect +ve lead to term’l

1 & –ve

lead to

term’l 2

Connect –ve lead to term’l

1 & +ve

lead to

term’l 2

Channel

isolation

test

Table 28: Tests for diode-return barriers

The table gives details for testing positive polarity barriers. For negative polarity barriers the same values apply, but the multimeter and supply leads must be reversed.

Table 29: Tests for fieldbus barriers

This barrier has to provide balanced operation of the fieldbus with respect to earth. It therefore has identical positive and negative polarity channels. A fieldbus terminator is also included in the barrier.

INM700-10 June 2005

APPENDIX A: ATEX certification information

The Essential Health and Safety Requirements (Annex II) of the EU Directive 94/9/EC [the ATEX Directive - safety of apparatus] requires that the installation manual of all equipment used in hazardous areas shall contain certain information. This annex is included to ensure that this requirement is met. It compliments the information presented in this document and does not conflict with that information. It is only relevant to those locations where the ATEX directives are applicable.

General

a) In common with all other electrical apparatus installed in hazardous

areas, this apparatus must only be installed, operated and maintained by competent personnel. Such personnel shall have undergone training, which included instruction on the various types of protection and installation practices, the relevant rules and regulations, and on the general principles of area classification. Appropriate refresher training shall be given on a regular basis. [See clause 4.2 of EN 60079-17].

b) This apparatus has been designed to meet the requirements of asso-

ciated electrical apparatus in accordance with EN 50020 and EN50014.

c) This apparatus has been designed and manufactured so as to pro-

vide protection against all the relevant additional hazards referred to in Annex II of the directive, such as those in clause 1.2.7.

Installation

a) The installation should comply with the appropriate European,

national and local regulations, which may include reference to the IEC code of practice IEC 60079-14. In addition particular industries or end users may have specific requirements relating to the safety of their installations and these requirements should also be met. For the majority of installations the Directive 1999/92/EC [the ATEX Directive - safety of installations] is also applicable.

b) This apparatus is an associated electrical apparatus and is nor-

mally mounted in a non-hazardous [safe] area. When mounted in a Zone1 location the apparatus must be provided with an enclosure, which offers an additional degree of protection appropriate to the area classification

c) This apparatus must not be subjected to mechanical and thermal

stresses in excess of those permitted in the certification documentation, this manual and the product specification. If necessary the product must be protected by an enclosure to prevent mechanical damage.

d) The apparatus must not be installed in a position where it may be

attacked by aggressive substances and must be protected from excessive dust, moisture and other contaniments by an enclosure.

Inspection and maintenance

a) Inspection and maintenance should be carried out in accordance

with European, national and local regulations which may refer to the IEC standard IEC 60079-17. In addition specific industries or

end users may have specific requirements which should also be met. b) Access to the internal circuitry must not be made during operation. c) If the outer enclosure of the apparatus needs to be cleaned, this

should be done with a cloth lightly moistened by a dilute mixture of

detergent in water.

Repair

a) These barriers must not be repaired. A barrier must be replaced

by an equivalent certified product.

Marking

MTL700 Series barriers carry a certificate number as detailed in Table 12. Each device is also CE marked with the Notified Body Identification Number of 1180, and carries the following information:

a) Company logo

b) Company Name and Address

c) Product Number and Name

d) Certificate Number(s)

e) Ex Classification (where applicable)

f) Schematic diagram

g) Safety description parameters

h) Ambient temperature range

This manual applies to products date marked 2002 or later.

MTL 755ac Shunt-diode safety barrier

BAS01ATEX7202 Um : 250V

Made by

MTL Instruments Pvt. Ltd.

Chennai, India

Haz

Safe

1180

Int. safe connections to Cl. I, Groups A,B,C,D; Cl. II, Groups E,F,G; Cl. III. See Drawing SCI-193 for connections. Voc £ 2.96V, Isc £ 296mA, Ca £ 346µF La £ 0.4mH, La/Ra £ 70µH/W. Vmax £ 250V r.m.s.

LISTED

73P6

Approved

Int. safe connections to Cl. I, Div.1 Gps A,B,C,D; Cl. II, Div.1, Gps E,G; Cl. III, Div.1. Dwg SCI-88 Voc £ 5.92V, Isc £ 296mA, Ca £ 1000µF La £ 0.4mH. Vm £ 250V r.m.s.

II (1)GD [EEx ia] IIC

-20°C £ Ta £ +60°C Uo : 3V Io : 300mA

3V 10W 3V 10W

Max amb temp 60°C

Figure A1: Typical MTL700 Series barrier label

Table 11:

MTL700 Series Safety parameters

Model No. V

ΩΩ

MTL702 25 200 125 MTL706 28 300 93 MTL707 28 300 93

28 -

MTL707P 28 164 170

15 -

MTL708 28 300 93 MTL710 10 50 200 MTL710P 10 33 300 MTL715 15 100 150 MTL715P 15 50 291 MTL722 22 150 147 MTL722P 22 101 213 MTL728 28 300 93 MTL728P 28 234 119 MTL729P 28 164 170 MTL751 1 10 100

1 10 100

MTL755 3 10 300

3 10 300

MTL758 7.5 10 750

7.5 10 750

MTL761 9 90 100

9 90 100

MTL761P 9 350 25

9 350 25

MTL764 12 1k 12

12 1k 12

MTL766 12 150 80

12 150 80

MTL766P 12 75 157

12 75 157

MTL767 15 100 150

15 100 150

MTL768 22 150 147

22 150 147

MTL779 28 300 93

28 300 93

MTL796 26 300 87

20 390 51

MTL760 10 50 200

10 50 200

MTL765 15 100 150

15 100 150

MTL772 22 300 73

22 300 73

MTL778 28 600 47

28 600 47

MTL786 28 -

28 -

MTL787 28 300 93

28 -

MTL787S 28 300 93

28 -

MTL787SP 28 234 119

28 -

MTL788 28 300 93

10 50 200

MTL788R 28 300 93

10 50 200

MTL791 11 51 216

11 51 216

MTL799 ---

INM700-10 June 2005

Model No. (V) (ΩΩ) (mA) MTL7122+ 22 150 147 MTL7028+ 28 300 93 MTL7128+ 28 300 93 MTL7128P+ 28 234 120 MTL7129P+ 28 164 171 MTL7028– 28 300 93 MTL7128– 28 300 93 MTL7162+ 10 50 200

10 50 200

MTL7164+ 12 1k 12

12 1k 12

MTL7167+ 15 100 150

15 100 150

MTL7096– 26 300 87

20 390 52

MTL7196– 26 300 87

20 390 52

MTL7087+ 28 300 93

28 –

MTL7187+ 28 300 93

28 –

MTL7087P+ 28 234 120

28 –

MTL7187P+ 28 234 120

28 –

MTL7055ac 3 10 300

3 10 300

MTL7056ac 3 10 300

3 10 300 3 10 300

MTL7261ac 9 90 100

9 90 100

MTL7061Pac 9 350 26

9 350 26

MTL7161Pac 9 350 26

9 350 26

MTL7264ac 12 1k 12

12 1k 12

MTL7066Pac 12 75 160

12 75 160

MTL7166Pac 12 75 160

12 75 160

MT7060ac 9 75 120

9 75 120

MT7160ac 9 75 120

9 75 120

MT7265ac 15 100 150

15 100 150

MT7278ac

28 600 47 28 600 47

MT7106

28 300 93

MT7206

28 300 93

MT7207+ 28 300 93

28 –

MT7208+ 28 300 93 MT7099 ––– MT7299 –––

Number of Maximum permissible

single channels cable parameters

interconnected Earth1BASEEFA (group IIC (hydrogen)) Matched

within the return Capacitance Inductance L/R ratio power

Model no. hazardous area used? (µF) (mH) (µH/ΩΩ) (W)

MTL7106/7206 1 Yes 0.083 4.1 54 0.65 MTL7207+ 2 Yes 0.083 4.1 54 0.65 MTL7208+ 1 Yes 0.083 4.1 54 0.65 MTL7122+ 1 Yes 0.165 1.66 44 0.81 MTL7028+/7128+ 1 Yes 0.083 4.1 54 0.65 MTL7128P+ 1 Yes 0.042 1.26 42 0.83 MTL7028–/7128– 1 Yes 0.083 4.1 54 0.65 MTL7129P+ 1 Yes – – – 1.19 MTL7055ac 1 Yes 1000 0.4 158 0.23

2 Yes 1000 0.1 79 0.45 2 No 40 0.4 79 0.45 3 No 40 0.22 59 0.68 4 Yes 40 0.035 31.25 0.92

MTL7056ac 1 Yes 1000 0.4 158 0.23

3 No 40 0.22 59 0.68

MTL7060ac/7160ac 1 Yes 4.9 2.47 131 0.27

2 Yes 4.9 0.61 65 0.54

MTL7061Pac/7161Pac 2 No 0.309 54.2 307 0.12 MTL7261ac 1 Yes 4.9 3.55 158 0.23

2 Yes 4.9 0.88 79 0.45

MTL7162+ 1 Yes 3.0 0.89 71 0.50

2 Yes 3.0 0.22 35 1.0 2 No 1.97 2.93 117 –

MTL7164+ 1 Yes 1.41 246 987 0.04

2 Yes 1.41 61.7 493 0.08

MTL7264ac 1 Yes 1.41 246 987 0.04

2 Yes 1.41 61.7 493 0.08

No 0.125 246 493 0.08

MTL7265ac 1 Yes 0.58 1.58 63 0.56

2 Yes 0.58 0.4 31 1.13

MTL7066Pac/7166Pac 2 Yes 1.41 0.36 37 0.96 MTL7167+ 1 Yes 0.58 1.58 63 0.56

2 Yes 0.58 0.4 31 1.13

MTL7278ac 1 Yes 0.083 16.1 108 0.33

2 Yes 0.083 4.02 54 0.66

MTL7087+/7187+ 2 Yes 0.083 4.1 54 0.65 MTL7087P+/7187P+ 2 Yes 0.042 1.26 42 0.84 MTL7096–/7196– 2 Yes 0.134 1.86 44 0.83

MTL Instruments Pty Limited

1/30 Canvale Road Canning Vale Perth, WA 6155 Australia Tel: +61 (0)8 9455 2994 Fax: +61 (0)8 9455 2805 E-mail: enquiries@mtlaus.com.au

MTL Canada Safety Instrumentation

#102, 4249 97 Street Edmonton, Alberta Canada T6E 5Y7 Tel: +1 780 485 3132 Fax: +1 780 485 3122 E-mail: cinfo@mtlnh.com

MTL Instruments Pte

Room 1002A, The Gateway No 10 Yabao Road, Chaoyang District Beijing 100020 China Tel: +86 010 8562 5718/5720/5721 Fax: +86 010 8562 5725 E-mail: bjsales@mtl-inst.cn

MTL Instruments sarl

Les Carrés du Parc 10 rue des Rosiéristes 69410 Champagne au Mont d’Or France Tel: +33 (0)4 78 64 98 32 Fax: +33 (0)4 78 35 79 41 E-mail: info@mtl-inst.fr

MTL Instruments GmbH

An der Gümpgesbrücke 17 D-41564 Kaarst Germany Tel: +49 (0)2131 718930 Fax: +49 (0)2131 7189333 E-mail: info@mtl.de

MTL India

No. 36, Nehru Street Off Old Mahabalipuram Road Sholinganallur Chennai - 600 119 India Tel: + 91 (0)44 24501660/24501857 Fax: + 91 (0)44 24501463 E-mail: sales@mtlindia.com

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Via Cantù 11 I - 20092 Cinisello Balsamo MI Italy Tel: +39 (0)2 61802011 Fax: +39 (0)2 61294560 E-mail: info@mtl-inst.it

MTL Instruments KK

3rd Floor, Gotanda Masujima Building 1-8-13 Higashi-Gotanda, Shinagawa-Ku Tokyo 141-0022 Japan Tel: +81 (0)3 5420 1281 Fax: +81 (0)3 5420 2405 E-mail: sales@mtlkk.co.jp

MTL Instruments BV

PO Box 55, 6680 AB Bemmel de Houtakker 36, 6681 CW Bemmel The Netherlands Tel: +31 (0)481 450250 Fax: +31 (0)481 450260 E-mail: info@mtlbenelux.com

MTL Instruments Pte Limited

31 Ubi Road 1 #04-01 Aztech Building Singapore 408694 Tel: +65 6 487 7887 Fax: +65 6 487 7997 E-mail: sales@mtlsing.com.sg

MTL Instruments

Villa No. 4, Sector 2-17, Street 6 PO Box 53234, Abu Dhabi, UAE Tel: +971 2 446 6840 Fax: +971 2 446 6841 E-mail: mtlgulf@mtl-inst.com

Measurement Technology Limited

Power Court, Luton, Bedfordshire England LU1 3JJ Tel: +44 (0)1582 723633 Fax: +44 (0)1582 422283 E-mail: enquiry@mtl-inst.com

MTL Incorporated

4001 W. Sam Houston Parkway N., Suite 150 Houston TX 77043 USA Tel: +1 281 571 8065 Fax: +1 281 571 8069 E-mail: info@mtl-inst.com

Group Internet home page http://www.mtl-inst.com/

Members of The MTL Instruments Group

MTL Instruments MTL700 Operating Manual

Specifications and Main Features

Frequently Asked Questions

User Manual