Oldham MX48 Commissioning, Operating And Maintenance Manual

CCOOMMMMIISSSSIIOONNIINNGG,, OOPPEERRAATTIINNGG AANNDD

MMAAIINNTTEENNAANNCCEE MMAANNUUAALL

GAS AND FLAME DETECTION

STACK GAS AND DUST MONITORING

We thank you for choosing an OLDHAM SA instrument.

We have taken every step to ensure that this equipment continues to give you complete satisfaction.

Please read the instruction manual carefully before using the instrument.

LLIIMMIITTSS OOFF RREESSPPOONNSSIIBBIILLIITTYY

* OLDHAM SA hereby rejects any and all responsibility with regard to any person for material

damage, bodily injury or death resulting in whole or in part from the inappropriate use, installation or storage of its equipment not conforming to the instructions and to warnings and/or not conforming to standards and regulations in force.

* OLDHAM SA does not allow or authorize any company, person or legal entity to assume such

responsibility on the part of OLDHAM SA, even if involved in the sale of the products of OLDHAM SA.

* OLDHAM SA shall not be liable for any direct or indirect damage, or any direct or indirect

legally awarded damages resulting from the sale and use of any of its products, UNLESS

THOSE PRODUCTS WERE SPECIFIED AND CHOSEN BY OLDHAM SA FOR THE USE MADE OF THEM.

OOWWNNEERRSSHHIIPP CCLLAAUUSSEESS

* Sketches, drawings, specifications and data included herein contain confidential

information which is the property of OLDHAM SA.

* These information shall not be, in part or in whole, physically, electronically or in any

other form whatsoever, reproduced, copied, divulged, translated, used as a basis for the manufacture or sale of OLDHAM SA equipment or used for any other reason without

the prior approval of OLDHAM SA.

WWAARRNNIINNGGSS

* This document is not a contractually binding document, OLDHAM SA reserves the right

to make any changes, without notice, to the technical characteristics of its equipment in order to improve performance levels, in the interest of its customers.

* CAREFULLY READ THE INSTRUCTIONS BEFORE ALL FIRST USE:

This instruction manual must be read by any person who is, or will be, responsible for the use, maintenance or repair of this equipment.

* This equipment will conform with the specified performance levels only if it is used,

maintained and repaired in accordance with the directives of OLDHAM SA and by OLDHAM SA personnel or personnel authorized by OLDHAM SA.

CCOONNTTEENNTTSS

1. DESCRIPTION...........................................................................................7

1.1. General.............................................................................................................................7

1.2. the wall-mounted box.......................................................................................................9

1.3. The various printed circuit boards...................................................................................9

2. INSTALLATION AND CONNECTIONS .............................................. 10

2.1. Installation: recommendations.......................................................................................10

2.2. Electrical connections of the MX48 Unit (Fig. 8)..........................................................10

2.2.1. Alternative power supply.......................................................................................10

2.2.2. DC power supply....................................................................................................11

2.3. Detectors (Figure 12).....................................................................................................11

2.3.1. Explosimetric detectors of PONT type ..................................................................11

2.3.2. 3-wire detectors 4-20 mA: 3 connecting wires for shielded cable.........................11

2.3.3. 2-wire detectors 4-20 mA: 2 connecting wires for shielded cable.........................12

2.3.4. FIRE detectors: 2 connecting wires for shielded cable..........................................12

2.3.5. FLAME detectors: 2, 3 or 4 connecting wires for shielded cable depending on

utilization................................................................................................................................12

2.3.6. CO2 detector of type “Ventostat VT”....................................................................14

2.3.7. Specific case of intrinsic safety detectors ..............................................................14

2.3.8. Other detectors with standardized current output ..................................................15

2.3.9. Parking application.................................................................................................15

2.4. Connecting the unit to external devices.........................................................................16

2.4.1. Slaving controls......................................................................................................16

2.4.2. 4-20 mA current outputs (Fig. 12) .........................................................................17

2.4.3. RS 232 and RS 485 outputs ...................................................................................17

2.4.4. Remote acknowledgement.....................................................................................19

3. STARTING UP ......................................................................................... 20

3.1. Checking the installation................................................................................................20

3.2. Switching on the unit......................................................................................................20

3.3. Operating modes............................................................................................................21

3.3.1. Audio warning device (buzzer)..............................................................................21

3.3.2. Light-emitting diodes (LED) (Fig. 1 and fig 4) .....................................................21

3.3.3. Alarm thresholds....................................................................................................22

3.3.4. Fault thresholds......................................................................................................26

3.3.5. Measuring unit.......................................................................................................27

4. UTILIZATION .........................................................................................28

4.1. List and functions of the various items of “USER” equipment for programming and

calibration of the unit.................................................................................................................28

4.1.1. Keypads..................................................................................................................28

4.1.2. Maintenance keys...................................................................................................29

4.1.3. Potentiometers........................................................................................................29

4.2. Menus.............................................................................................................................30

4.2.1. The various menus and their functions ..................................................................30

4.2.2. Block diagram of the scrolling of the various menus.............................................30

4.2.3. Detailed flow diagrams of each menu....................................................................32

5. SETTING THE MX48 UNIT INTO SERVICE...................................... 45

5.1. Programming the unit....................................................................................................45

5.2. Programming the measuring channels..........................................................................45

5.2.1. Programming..........................................................................................................45

5.2.2. Copy.......................................................................................................................46

5.3. Calibrations....................................................................................................................46

5.4. 4-20 mA output adjustment for a measurement channel................................................49

6. MAINTENANCE...................................................................................... 50

6.1. Periodic / preventive maintenance.................................................................................50

6.1.1. On the MX48 unit ..................................................................................................50

6.1.2. On the detectors......................................................................................................50

6.2. Failures: causes and remedies.......................................................................................51

6.3. List of spare and replacement parts...............................................................................54

7. DETAILED TECHNICAL CHARACTERISTICS................................ 55

8. VIEWS SPECIFIED IN THE MANUAL................................................ 57

11..

DDEESSCCRRIIPPTTIIOONN

1.1. General

The MX48 measuring and alarm unit can be fitted with between one and 16 independent channels.

Each channel is connected to one or more detectors installed in the locations to be monitored.

The measurement that is output from the detector is displayed on the MX48 unit and compared with alarm thresholds. If thresholds are exceeded, the unit actuates relays which can be used to control external devices.

REMARK

The equipment of the MX48 unit comprises 1 or 2 PCBs (option), each equipped with 4 channels. However, each channel is independent and can be connected to any type of OLDHAM detector provided that the PCB is suitably programmed.

MMAAIINN CCHHAARRAACCTTEERRIISSTTIICCSS

• Wall-mounted box (500 x 340 x 89)

• AC or DC power supply

• 4 or 8 measuring inputs for detectors

• Display of measurement on a plasma display panel (2 lines - 16 characters)

• One keypad with four keys on the front panel for the user

• One keypad with four keys for maintenance (on the display unit card, accessible only by

opening the front panel)

• One “CALIBRATION” key and one “PROGRAMMING” key for maintenance (on the

display unit card, accessible only by opening the front panel)

• 3 gas alarms per channel

- Two instantaneous rising or falling thresholds, manual or automatic clearing, with

“extractor control logic (tunnel parking application)”

- One rising or falling threshold, automatic clearing, triggering by time delay or

average

Relaying

Total of 10 or 18 relays distributed as follows:

- Two relays per channel, with positive or negative safety, contacts open or closed

at rest for the first two thresholds

- One relay common to channels for third thresholds or for all alarms (buzzer

transmission), with positive or negative safety, contacts opened or closed at rest

- One relay common to channels for faults and failures, constant positive safety

mode, contacts open or closed at rest.

• Current output (4-20 mA) per measuring channel.

• Common audio alarm that can be acknowledged in the case of occurrence of gas alarms.

1.2. the wall-mounted box

The housing of the MX48 is a wall-mounted box consisting of a back casin and a cover which can be pivoted.

• Dimensions: Fig. 1 (end of this manual)

• Overall view, casing open : Fig. 2

1.3. The various printed circuit boards

• Overall view: Fig. 2

• Power supply board : Fig. 3

• Measuring channel board: Fig. 7

• Front link board : Fig. 4

(Comprising the display, the micro part, the DB9 RS223 and RS485 connector and the keypads).

FIGURE 2 : COMPLETE SET OF BOARDS

VUE D'ENSEMBLE DU MX48 (carter ouvert)

Figure N°2

(voir fig N°4)

(voir fig N°3)

(voir fig N°7)

(voir fig N°1)

Transformateur

Coffret MX48

15 presses-étoupes PG9

Carte afficheur

Carte alimentation

2 vérrouillages 1/4 de tour

Clavier déporté

Compas pour retenir le couvercle en position haute

Première carte voie de mesure

Deuxième carte voie de mesure

MX48 box

(see Fig. n°1)

Stay for holding up the

cover

Transformer

Power supply board

(see fig. N°3)

Second measurement

channel board (see fig. N°7)

OVERALL VIEW OF THE MX48

(casing open)

FIGURE 2

15 PG9 cable glands

First measurement channel

board (see fig. N°7)

Display board

(see fig. N°4)

Offset keypad

¼ turn latches – 2 off

22..

IINNSSTTAALLLLAATTIIOONN AANNDD CCOONNNNEECCTTIIOONNSS

2.1. Installation: recommendations

The MX48 unit can be installed in any premises without an explosive atmosphere. They should preferably be placed in a ventilated and monitored location (guardhouse, control room, instrumentation room, etc.).

Attachment is to be ensured in accordance with the dimensions in Figure 1 (3 attachment points).

REMARK

In order to permit the swivelling front panel of the unit to be opened completely, allowance must be made for opening by rotation through 90° downwards (see fig 2 – end of this manual)

Before making any connections, the unit should be switched off using the main On/Off switch below and to the left of the FRONT circuit (see Figures 3 rep A).

2.2. Electrical connections of the MX48 Unit (Fig. 8)

The MX48 unit is equipped with a pulse automatic device which enables to connect 24 V DC voltage in a lack of 220 V AC voltage so we can use no expansive save power supply.

2.2.1. Alternative power supply

- Voltage: 230 V AC (207 to 244 V) 50/60 Hz

- Maximum power: 200 VA

- Maximum current in cable: 1 A

- Cable: 3 x 1.5 mm² (including earth)

- Location of connection terminal blocks: Fig. 8,

- Protection: the phase and neutral wires are protected by time-delayed 2 A

fuses located at the rear of the power module (fig3).

- Voltage: 103 to 122 V AC - 50/60 Hz on option

CAUTION

It is mandatory that the appliance must be earthed. A terminal is reserved for this purpose at the back of the power module: see Fig. 5. This connection is required in order to ensure correct operation of the following:

- mains power interference filter,

- protective devices against electromagnetic interference.

2.2.2. DC power supply

- Voltage: 21 to 30 V continue. The "-" from continue power supply is linked to

earth (and earth being linked to frame).

- Maximum power: 150 W

- Maximum current in cable: 6.3 A

- Cable: 2 x 2.5 mm²

- Location of terminal block: see Fig. 8, item D

- Protection: by two fuses located at the back of the power module (Fig. 3)

2.3. Detectors (Figure 12)

REMARK

- The detectors are linked by SHIELDED cables.

- The utilization of shielded cables is MANDATORY

- The earth braid of shielded cables must be connected to the earth at one end

only.

CAUTION Each channel is configured in the factory for a given type of detector (explosive gas, toxic gas, fire or flame). If two different types of detector are interchanged, this may result in

the destruction of the central unit or of the detector.

2.3.1. Explosimetric detectors of PONT type

Three connecting wires for a shielded cable.

Resistance of detector / unit cable: 16 ohms maximum per wire, i.e. 32 ohms in loop (1 km for cable 3 x 1.5 mm²).

Connection on MX48 unit: see Fig. 10 – Example 1

2.3.2. 3-wire detectors 4-20 mA: 3 connecting wires for shielded cable

- Resistance of detector / unit cable: 16 ohms maximum per wire, i.e. 32 ohms in loop

(1 km for cable 3 x 1.5 mm²).

- Connection on MX48 unit: see Fig. 10. – Example 2

2.3.3. 2-wire detectors 4-20 mA: 2 connecting wires for shielded cable

- Resistance of detector / unit cable: 32 ohms maximum per wire, i.e. 64 ohms in loop

(2 km for cable 2 x 1.5 mm²).

- Connection on MX48 unit: see Fig. 11. – Example 2

2.3.4. FIRE detectors: 2 connecting wires for shielded cable

The current commercial designations are as follows:

- “Thermovelo” detectors of type EC 11 (sensitive to temperature variations)

- Ionic detectors of type EI 1 100 (sensitive to smoke)

- Optical detectors of type EO 1 100 (sensitive to smoke)

- Resistance of detector / unit cable: 28 ohms maximum per wire, i.e. 56 ohms in loop (2 km for

cable 2 x 1.5 mm²)

- Fire detectors can be detected in parallel to a maximum of five. The end-of-loop resistor

(2.7 K) is to be placed at the end of the line on the last detector.

- Connection on MX48 unit: see Fig. 11. – example 1

2.3.5. FLAME detectors: 2, 3 or 4 connecting wires for shielded cable depending on utilization

REMARK

The detectors can be supplied with power either via the MX48 unit or by an auxiliary 24 V DC source.

These detectors can operate in standalone mode:

24 V DC power supply and direct utilization of relay contacts in accordance with the technical specification corresponding to the detector used.

The current commercial designations are as follows:

- model 20/20 U - analog - type UV - 752002 (sensitive to UV radiation)

- model 20/20 UC - analog - type UV (sensitive to UV radiation)

- model 20/20 UB - µP technology - type UV - 772002 (sensitive to UV radiation)

- model 20/20 UBC - µP technology - type UV (sensitive to UV radiation)

- model 20/20 LC - analog - type UV/IR (pyroelectric, combination of UV and IR

detectors)

- model 20/20 LBC - µP technology - type UV/IR (pyroelectric, combination of UV and

IR detectors)

- model 20/20 I - µP technology - triple IR detector - 780002 (pyroelectric, sensitive to IR

radiation)

These detectors are equipped with various types of terminal block (see table below).

Model 20/20 U 20/20 UC 20/20 UB 20/20 LC 20/20 UNC 20/20 LBC 20/20 I

Type

of terminal

block

- Resistance of cable / unit

- In the case of local 24 V DC power supply:

8.5 ohms maximum per wire, i.e. 17 ohms in loop

- In the case of power supply via the MX48 unit:

3 ohms maximum per wire, i.e. 6 ohms * in loop

∗ 4 ohms for detector 20/20 I (IR3)

- Connection on MX48 unit (ONE detector per measuring channel ONLY):

- detector equipped with a terminal block of type A: see Fig. 13

- detector equipped with a terminal block of type B: see Fig. 14

- detector equipped with a terminal block of type C: see Fig. 15

Example of the utilization of the 4-20 mA signal from flame detectors equipped with connectors of type A or C: see Fig. 16.

Example of the utilization of detectors equipped with connectors of either type A or type B and with auxiliary power supply. The auxiliary power supply must be able to supply power to the number of detectors planned in the measuring loop (see Fig. 17).

REMARK

In the case of this application, the maximum of five flame detectors can be connected in the measuring loop.

Example of the utilization of IR3 or UV/IR detectors equipped with connectors of type A with a local junction box and galvanic insulation (see Fig. 18).

2.3.6. CO2 detector of type “Ventostat VT”

- Connection on MX48 unit: see Fig. 20.

- Resistance of detector/unit power cable: 12 ohms maximum per wire, i.e. 24 ohms in

loop.

- 4-20 mA output: maximum load = 280 ohms (whole loop)

2.3.7. Specific case of intrinsic safety detectors

Two types of intrinsic safety barrier can be used: Z787 / EX and MTL787S+.

PRECAUTIONS

Before connecting the barrier to the unit, check that the voltage is < 25 V DC.

- A short circuit in the electrical connections will result in destruction of the barrier.

- Perform wiring in the DE-ENERGIZED state.

- The electrical link between the MX48 unit and the clipper is made using a screened

cable with two active conductors with a maximum resistance of 12 ohms each.

REMARK In classified areas, the installation must comply with the standards in force.

- Connections on MX48 unit: see Fig. 21.

IMPORTANT All intrinsic safety installations must be APPROVED as a whole assembly by an approved

organization (DRIRE, etc.).

OLDHAM “INTRINSIC SAFETY” BARRIERS

Type of IS

barrier

Reference Specific features OLDHAM box

reference

Z787 / EX 6184703 To be fitted on DIN

RAIL

MTL787S+ 6797100 To be fitted in an

approved box: MANDATORY

For 2 clippers 6797192

For 5 clippers 6797547 For 12 clippers 6797101

2.3.8. Other detectors with standardized current output

Any detector (with 2 wires or 3 wires) that can be supplied with power between 19 V DC and 32 V DC and that supplies a standardized current (signal) of between 4 and 20 mA can be connected to the MX48 unit.

The connection requirements are identical to those for the corresponding OLDHAM detectors (see Fig. 22).

2.3.9. Parking application

CTX300 "Co parking" toxic gas detectors can be fitted in parallel when a mean gas concentration is to be obtained. The detectors must, imperatively, be located in the same area. In this case, a maximum of five detectors can be connected (see Fig. 23).

2.4. Connecting the unit to external devices

2.4.1. Slaving controls

The 8 measuring channels of the MX48 unit are each equipped with two relays which can be used to control external devices: sirens, solenoid valves, extractors, telephone calls, etc..

For each measuring channel, the relays are distributed in the following manner (see Fig. 7):

- a relay associated with the triggering of alarm 1 (fig 7),

- a relay associated with the triggering of alarm 2 (fig 7),

- use of open or closed contacts selected with a jumper (see Fig. 7 – item A),

- use of positive or negative safety selected by programming (see the CHANNEL

programming menu),

- contact outputs on the back of the measuring board (see Fig. 12).

- An example of connection is given in Fig. 24:

- a siren connected to relay AL1 will be actuated as soon as alarm 1 is triggered,

- a solenoid valve connected to relay AL2 will be actuated as soon as alarm 2 is

triggered.

For all channels:

- A common relay associated with the triggering of alarm 3 for the 8channels (fig 3).

By programming, this common relay can also be used for the remote transmission of the audio warning signal. (This relay will then be associated with all the unit’s alarms).

- A fault relay associated with the triggering of channel faults (detector failures, electrical

connections, excessively negative zero, etc.). This relay will always be in positive safety mode (see Fig. 3).

- The use of open or closed contacts is selected by programming on common board (see

Fig. 3).

- Common relay contact outputs on the back of the power module: Fig. 8.

REMARK

Owing to the breaking capacity of the MX48 unit’s relays which is limited to 2 A / 250 V AC or 30 V DC, external intermediate relays must be used if the devices to be controlled require high power levels.

The relay contacts are indicated : unit switched off

2.4.2. 4-20 mA current outputs (Fig. 12)

For each measuring channel, the MX48 unit is equipped with a 4-20 mA output that can be used to retransmit measurements to a recorder or an external PLC. The maximum resistance in loop mode is 600 ohms. The earth connections for the 4-20 mA outputs are common and the unit. The 4-20 mA lines are not galvanically insulated one from the other. The current output varies according to the measurement and has several states, as follows:

- On starting up the unit: I < 1 mA

- With FAULT: I < 1 mA

- In MAINTENANCE mode: I = 2 mA

- ZERO MEASUREMENT: I = 4 mA

- Full scale: I = 20 mA

- Out of range or “in doubt”: I > 23.2 mA

An example of the connection of a multi-channel recorder is given in Fig. 25.

2.4.3. RS 232 and RS 485 outputs

RS232 OUTPUT

A computer can be connected on a female sub.D/DB9 type connector located on the back of the micro board (fig 4 repA). The MX48 programming, from outside, will be possible thanks to this connection.

RS 232 OUTPUT USING

- Remove the DB9 connector (plug with an internal strap)

- Connect a link cable ref.6315831 which will link the monitor to the computer on the

MX48 available female connector DB9 (Fig 6)

- when the using is stopped : no connect the cable and put the male DB9 "plug" again.

Female DB9

Male DB9

MX48

PC COMPUTER

RS 485 OUTPUT (PINABLE ON FIG 8)

Several MX48 units can be linked to a single computer, which is the "master" of the network. In this case, a "SLAVE NUMBER" (by programming/unit) is asigned to each MX48 unit.

This RS 485 output can be galvanically insulated as an option.

1st case : no galvanic insulation

- no mounted insulation component

- 2 polarization electrical resistances are welded and programmed with J103 and J104 pins

2nd case : with galvanic insulation

- mounted and welded insulation component

- no programmed polarization electrical resistance for "plus" (+ 5V) (J104 programming

pins)

a) with RS 485 shielded

- no programmed polarization resistor for "moins" (GND) (J103 programming

pins)

b) without RS485 shielded

- programmed polarization resistor for "moins" (GND) (J103 programming pins)

End loop resistor

It is located on the MX48 micro board and must be programmed with the last MX48 unit of the loop (by pins) with a 120 Ohms value.

The MX stored data are some instantaneous values

The RS485 output is a half duplex type.

RS 485 OUTPUT USING

- No change the sub D/DB9 "plug" connector (fig 4 – item A)

- Connect the screwed connector terminals 3, 4 and 5, located on the power supply board

of the MX48 unit. See connection details fig 8.

- Owing to mounted wires or not (following the mounting and the equipment linked or not

on the earth…).

IMPORTANT

All details regarding the RS 485 complete description (Modbus / Jbus format, structures, adresses aso…) are developped in a leaflet ref. D 813 577.

CAUTION

A computer or a printer management interface must be used in order to printout the data stored by the MX48 unit. See details and possibilities in a leaflet ref. 8 813 571.

2.4.4. Remote acknowledgement

It is possible to allow remote acknowledgement by connecting on terminals clear 1 and clear 2 (loop  16 mA), of the connector located on the power supply board : see fig 8. Maximum load impedance : 1 K Remark : several MX48 units can be connected to the same remote acknowledgement system provided that the polarities are respected.

Power supply terminal

Transformer terminal

Clear and RS485 terminal terminal

33..

SSTTAARRTTIINNGG UUPP

3.1. Checking the installation

It is checked that, at least, all connections have been made and that the complete installation complies with current standards in force.

CAUTION OLDHAM is not responsible for the compliance of the complete electrical safety system.

The MX48 unit is switched on by means of circuit breakers * provided for that purpose and which ensure protection of the mains power unit.

* The circuit breakers are to be selected according to the power consumption levels specified by the manufacturer and the length of the electric cables.

3.2. Switching on the unit

CAUTION The handling operations and adjustments described in these paragraphs are strictly reserved for authorized personnel as they are liable to affect detection safety.

To start up the MX48 unit, you must:

- swivel the front panel,

- press the ON/OFF button located to the bottom left-hand side of the FRONT

circuit: see Figures 3 (item A).

- The display panel then shows, for example:

MX 48/52 V1.0

The unit then goes into INITIALIZATION mode for one minute. Consequently, all the alarms are inhibited and the current outputs are 1 mA for the channels in service. The unit then performs a selftest * on its buzzer and all its night-emitting diodes. At the end of this one-minute period, the channels in service return to normal operation and the corresponding alarms and relays are enabled.

* The user can carry out a “manual-self test” by pressing the test key at any time (see Fig. 26). This self-test lasts 20 seconds and the display panel may show the following displays one after the other, for example:

then

The user can interrupt the self-test cycle before it is completed by pressing the ACKNOWLEDGEMENT key of the front panel keypad.

3.3. Operating modes

3.3.1. Audio warning device (buzzer)

In normal operation, the audio warning device is triggered whenever a fault or an alarm appears. The audio warning device can be stopped by pressing the ACKNOWLEDGEMENT key or by remote acknowledgement. The buzzer makes a continuous or discontinuous sound (according to the programming of the unit) if an alarm threshold is exceeded.

3.3.2. Light-emitting diodes (LED) (Fig. 1 and fig 4)

Each channel is equipped with five LEDs (visible and identified on the FRONT panel).

LED Extinguished Illuminated

in steady mode

Flashing

GREEN Channel not in

service

Channel in service Threshold AL1 exceeded

(manual clearing) and not

acknowledged

1st red AL1 not triggered Threshold AL1 exceeded

(automatic clearing)

Threshold AL2 exceeded

(manual clearing) and not

acknowledged

2nd red AL2 not triggered Threshold AL2 exceeded

(automatic clearing)

3rd red AL3 not triggered Threshold AL3 exceeded by mean

or time (automatic clearing)

Yellow No fault Fault on channel -Channel being calibrated or

programmed

- Detector being calibrated

MX 48/52 V1.0

xx LEL CH4

*** SELF-TEST ***

xx LEL CH4

Line corresponding to the channel displayed when the ENTER key was pressed

3.3.3. Alarm thresholds

Each of the three alarm thresholds can be programmed independently for each channel. (See the “Channel programming” menu).

In normal operation, a gas alarm is only triggered after a preprogrammed time delay in order to avoid spurious alarms.

Alarm thresholds can be processed in the following manners:

- in normal cycle with manual clearing: block diagram 1,

- in normal cycle with automatic clearing: block diagram 2,

- in parking cycle: block diagram 3.

The alarm thresholds are to be selected according to the gases detected and the corresponding standards in force.

Special case: A channel connected to a fire detector

- It is MANDATORY to select the scale with 100 divisions.

- It is MANDATORY to select the alarm threshold with 60 divisions.

(Owing to the end-of-loop resistor of 2.7 kΩ, the fire detector outputs 4 mA when no fire is detected and 20 mA if a fire is detected).

BLOCK DIAGRAM 1

NORMAL CYCLE WITH MANUAL CLEARING

Alarm

acknowledged

LED extinguished Relay disengaged

Buzzer stopped

Illumination of flashing

alarm LED

After T2 time

START

Threshold

exceeded

Time T1

exceeded

Illumination of flashing

alarm LED

LED steady mode

Buzzer stopped

END

Relay engaged

Buzzer engaged

Yes

Alarm

acknowledged

BLOCK DIAGRAM 2

NORMAL CYCLE WITH AUTOMATIC CLEARING

START

Threshold

exceeded

Time T1

exceeded

LED extinguished

Relay disengaged

Alarm LED illuminated

in steady mode

After T2 time

Relay engaged

Buzzer engaged

END

Yes

BLOCK DIAGRAM 3

PARKING CYCLE

Alarm 3 operates in the same way as the normal cycle.

The times defined for alarms 1 and 2 (time delays) are, in this case, used to define the minimum operating time for each relay.

t AL1 tR1 R2 t AL2

Threshold AL2

Threshold AL1

Starting of

relay R1

Stopping

of relay R1

Starting of

relay R2

Stopping of

relay R2

min.

AL1

Min. operating time for alarm 1

(defined for each channel)

AL2

Min. operating time for alarm 2

(defined for each channel)

R1 R2

Switching time from relay 1 to relay 2

(defined for the whole unit)

R1 & R2

3.3.4. Fault thresholds

Processing of detector faults

Each channel detects the following faults.

For toxic and explosive gas detectors:

- line interrupted (0 mA),

- line short-circuited or excessive consumption,

- negative offset (more than 20% of measuring scale),

- line in calibration mode (2 mA) (if confirmed by programming).

For detectors of the explosive gas type (4-20 mA and 340 mA) in normal mode and if the measurement is greater than 100% of the measuring scale, there are the following immediate results:

- Display: SUP

- The relays are actuated if the thresholds are reached.

- The general fault relay is actuated.

- The 4-20 mA output of the channel is greater than 20 mA.

- All these states are memorized and the only way of acknowledging them is to

switch off the channel and then restart it.

Faults are valid after a preprogrammed time (in the same way as alarms).

FAULT BLOCK DIAGRAM

END

START

Wait until the fault has been present

for at least 5 seconds.

The relays are locked in their current state.

The common fault relay is engaged.

The buzzer is engaged.

The channel fault LED is illuminated. *

1 mA is sent on the 4-20 mA output.

* The LED is extinguished as soon a the fault disappears.

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Oldham MX48 Commissioning, Operating And Maintenance Manual

Specifications and Main Features

Frequently Asked Questions

User Manual