YOKOGAWA SC200 Instruction Manual

Instruction
Manual

Model SC200
2-wire Conductivity
or Resistivity transmitter

IM 12D7B2-E-H

4th edition

IM 12D7B2-E-H

FAILHOLD

MEASURE
CAL
DISPLAY
HOLD

YES

NO

ENT

OUTPUT

SET HOLD
TEMP.
SERVICE

*

NO MODEYES

>

ENT>

MODE

mS/cm
MΩ/cm

kΩ/cm
µS/cm

.

ADJUSTMENT KEYS

: Choose digit

for adjustment

: Adjust digit (to decrease

pass through zero)

ENT: Enter new value

MEASURE VALUE
DISPLAY

MESSAGE
DISPLAY

KEY PROMPT
FLAGS

SELECTION KEYS
YES: Accept

setting

NO: change to

new setting

L

L

SELECT MODE
MEASURE/MAINTENANCE

Can be used
to escape
program at any time

SELECT MODE
MEASURE/COMMISSIONING

OUTPUT
HOLD FLAG

MANUALLY SET
TEMPERATURE
COMPENSATION
FLAG

FAIL
FLAG

MENU POINTER
FLAGS

MENU FOR
MAINTENANCE
FUNCTIONS
see chapter 5

MENU FOR
COMMISSIONING
FUNCTIONS
see chapter 4

Note: First digit changes from 1,-1,- to blank.

TEMP.MAN

IM 12D7B2-E-H

1. INTRODUCTION

1-1. Application.................................................................1

1-2. Required components for

conductivity measurement .........................................1

1-3. Identification...............................................................2

2. TECHNICAL SPECIFICATIONS .........................................2

2-1. General technical specification...................................2

2-2. Functional description................................................3

3. INSTALLATION AND WIRING............................................4

3-1. Installation and dimensions ........................................4

3-1-1. Installation site.................................................4

3-1-2. Mounting methods ..........................................4

3-2. Wiring of sensors .......................................................6

3-2-1. General precautions ........................................6

3-2-2. Additional precautions for installations in

hazardous areas..............................................6

3-2-3. Grounding the liquid ........................................6

3-2-4. Access to terminal and cable entry..................6

3-2-5. Connecting diagram for sensors......................7

3-3. Wiring of power supply...............................................8

3-3-1. General precautions ........................................8

3-3-2. Additional precautions for installation

in hazardous areas ..........................................8

3-3-3. Access to terminal and cable entry..................8

3-3-4. Power on ........................................................8

4. COMMISSIONING.............................................................11

4-1. Operations overview ................................................11

4-2. Output range adjustment ............OUTPUT ..............12

4-3. Set up Hold function ...................SET HOLD ...........14

4-4. Temperature compensation ........TEMPERATURE...16

4-5. Sensor selection and diagnostics` ............................18

5. MAINTENANCE.................................................................20

5-1. Calibration...................................CAL......................20

5-2. Selecting a value to display .........DISPLAY..............22

5-3. Use of the hold function ..............HOLD...................24

6. TROUBLE SHOOTING......................................................26

6-1. Introduction .............................................................26

6-6. Error messages and explanation ..............................27

7. SERVICE (Mode) ...............................................................28

7-1. Introduction .............................................................28

7-2. Access to service settings........................................29

7-3. Temperature sensors and units................................30

7-4. Reference temperature ............................................30

7-5. Output code selection..............................................30

7-6. Output table for non-linear range .............................31

7-7. Cell constant adjustment..........................................31

7-8. Auto return function .................................................31

7-9. Measuring principle..................................................32

7-10. Temperature sensor adjustment...............................32

7-11. Signalling of fail condition.........................................32

7-12. Temperature compensation coefficient adjustment ..33
7-13. Percent by weight indication on second

display line ...............................................................34

7-14. Polarisation check....................................................34

7-15. Passcode protection by three digit code..................35

7-16. Restore default setting .............................................35

7-17. Non linear ranges.....................................................36

CONTENTS

IM 12D7B2-E-H

8. CLASSIFICATION .............................................................36

8-1. Cenelec ...................................................................36

8-2. FM...........................................................................37

9.

CHANGE FROM CONDUCTIVITY TO

RESISTIVITY MEASUREMENT .............

............................38

9-1. How to change from conductivity to resistivity

measurement...........................................................38

9-2. Resistivity measurement ..........................................38

9-3. Maintenance of the transmitter.................................38

10. SOFTWARE VERSION 3.0

COMPARED TO VERSIONS 1 AND 2 ............................39

10-1. Cell constant............................................................39

10-2. Matrix compensation ...............................................39

10-3. Matrix temperature-compensation range .................40

10-4. Matrix data...............................................................40

10-5. Selection between “soft” or “hard” Fail situations .....41

10-6. Selection between yes or no E6 Fail-message .........41

10-7. Matrix examples.......................................................42

IM 12D7B2-E-H

1

1. INTRODUCTION

1-1. Application

The EXA SC200 transmitter is a 2-wire con­ductivity instrument intended to be used in
industrial installations in the field. For easy
maintenance and operation it should be
located close to the sensors.
The cable length is limited to 10 metre.
It is powered from a remote low voltage DC
power supply through the 2-wire connec­tion.
The EXA SC200 is compatible with most
commercial available conductivity sensors
and fitting systems.
The instrument is available in two versions:

- A general purpose version for use in safe
areas.

- An intrinsically safe version for use in
hazardous areas. The instrument can then
be installed in Zone 1 with the sensors in
Zone 0 or Zone 1.

The micro-processor is used in this instru­ment for continuous loop diagnostics, flexi­ble on site commissioning and fine tuning by
advanced functions.

In general a conductivity loop can be set up
for different purposes:

- To be part of a total process control sys­tem.

- To indicate dangerous limits of a process.

- To monitor product quality.

1-2. Required components for

conductivity measurement

A. a conductivity sensor ( also called con-

ductivity cell) with integral temperature
sensor Ni-100 or Pt-1000.

B. a fitting for the above sensor with acces-

sories.

C. a signal cable with or without extension

boxes etc.

D. the EXA SC200 2-wire transmitter with

universal mounting accessory for wall,
pipe or panel mounting.

E. a DC power supply (nominal 24 V DC)

with cabling and optional zener barriers or
an intrinsic safe power supply.

F. peripherals: e.g. strip-chart recorder,

panel indicator, PID-controller

1-3. Identification

The instrument has an identification label,
which is fixed to the front plate.
This serves as a reference for the full model
code, power supply voltage and serial num­ber. This label also carries authorised marks
to certify compliance with the current regu­latory norms.

MODEL

SERIAL NO.

SUPPLY

IM 12D7B2-E-H

2. SPECIFICATIONS

2-1. General specifications

A. Intrinsic safety (model SC200S only)

- BASEEFA : Certified by and meets the requirements
of EEx [ia] ib IIC T4 of CENELEC
Certificate No.: 89C2379.

- FM : For IS CL1, DIV1, GP ABCD
T3B for TA-30 to 70˚C
T4 for TA-30 to 40˚C
Approval report: J.I. 1Y1A7.AX

- CSA : For Ex[ia] Class 1, Div. 1, Groups C
and D, T4A
Approval file: LR 102851-1

B. Indicating range : 0.055µS/cm to 2000 mS/cm at 25˚C

reference temperature with cell-con­stants between 0.01 to 10 cm

-1

C. Transmission signal : 4 - 20 mA DC; maximum load.550 Ω.
D. Transmission range : User programmable to any range within

the indicating range with a maximum of
60% zero suppression.
A user programmable output table can
be set up in 21 steps.

E. Power supply

- Model SC200G : 17 to 40 V DC, dependent on load.

- Model SC200S :

17 to 31,5 V DC, powered from a certified
zener barrier or isolated power supply

F. Climatic condition

- Ambient temperature : -10 to +55 ˚C(10 to 130°F)

- Storage temperature : -30 to +70 ˚C (-20 to 160°F)

- Relative humidity : 10 to 90%

- Weather protection : Rain and dust-tight to IP65 (NEMA 4X)

- Interference protection : EMI Class B
RFI less than 2% at 5 V/m for
20 MHz to 1 GHz.

G. Display method : Custom liquid crystal display.

- Main display : 31/2digit, 12.5 mm high.

- Message display : 6 alphanumeric characters, 7 mm.

- Special fields : Flags for status indication.
: Units: µS/cm, mS/cm.
: Key prompts: YES, NO, ^, >, ENT

H. Keys : 6 keys operated through the flexible win-

dow with tactile feedback and one hid­den key behind the front cover.

I. Housing

- Body material : Cast aluminium with chemical resistant

coating.

- Window : Flexible poly carbonat.

- Colours used : Moss green/ off-white.

- Cable glands : Polyamide

- Cable entries : Two glands PG 16 (

1

/2” NPT adapter for
US Model).
Hose connection optional.

- Terminals : For maximum 2.5mm

2

cable (cable

finishings preferred).

- Earth connection : For external ground.

J. Mounting possibilities

- Bracket mounting : Two M6 bolts, 9 mm length.
Wall, or pipe mounting by the optional
mounting kit, panel mounting by self tap­ping screws.

K. Shipping details

- Dimensions : 162 x 178 x 115 mm
(6.5 x 7 x 4.5”)

- Package : 290 x 225 x 170 mm
(11.5 x 8.9 x 6.7”)

- Weight : approx. 2,5 kg (5 Ibs)

L. Safety and security

- Data protection : Non volatile memory(EEPROM).

- Data backup : All data is stored 3 times.

- Interference test : according to IEC 801.

- Power down : no effect, reset to measurement.

- Operation : All 3 levels can be protected with a 3
digit passcode.

2

IM 12D7B2-E-H

3

2-2. Functional description

The EXA SC200 is a real time micro-control­ler operated conductivity-analyzing system.
It uses a dedicated micro-controller to con­trol all function necessary in such a system.
The input and output functions are concen­trated in the analogue section of the instru­ment. Even these functions are operated
through special interfaces designed to give
a minimum of interference problems to the
digital functions. A separation of function is
strictly executed.
By using very low power components it is
possible to make a complete micro-compu­ter system work on less than 4 mA current.
By using an EEPROM for essential informa­tion the operating parameters are fixed in
memory without the need for batteries. The
supply-voltage is stabilized by regulators to
the internal supply system. Any voltage
between 17 and 40 Volt is acceptable.
The user-interface is limited to a basic set of
6 keys accessible through the flexible win­dow cover.
The software is designed with the user in
mind. It uses a simple 3 layer set-up to
communicate with the operator by giving
messages on the second line of the display
area and indicating which keys are to be
pressed in the display too.

The keys are scanned continuously and the
actions are taken immediately. An extensive
system of checking values and parameters
is implemented.

The EXA SC200 operates just like a normal
2-wire instrument but with additional func­tions. These extra functions are possible by
using a micro-controller at the heart of the
system.

- Continuous sensor polarisation checking
during measurement.

- Automatic optimisation of measuring pulse
frequency and reference voltage.

- Accurate temperature compensation by
non liner NaCI algorithm.

- Simple output range adaptation making it
a versatile instrument.

- A HOLD-function for the current output
signal.

- Selection of temperature sensors.

- Passcode protection.

Additionally YOKOGAWA designed the in­strument in such a way that an intrinsically
safe version is available with the same featu­res and specifications. In fact the instrument
is only adapted slightly to fulfil the require­ments of CENELEC.

The instrument comes in 2 versions only:

-A general purpose model.

-An intrinsically safe model.

This makes it easy to set up the instrument
on site and valuable for large scale exchan­ges or emergency operations.

IM 12D7B2-E-H

3. INSTALLATION AND WIRING

3-1. Installation and dimensions
3-1-1. Installation site

As the transmitter is a rain-tight type, it can
be installed outdoors as well as indoors. It
should, however, be installed as close as
possible to the sensors avoiding long cable
lengths between sensors and transmitter.
The certified version can be installed in Zone

1.
Select an installation site where:

- mechanical vibrations and shocks are neg­ligible;

- no relay/power switches are in the direct
environment;

- the transmitter is not mounted in direct
sunlight and severe weather conditions;

- maintenance activities are possible (no
corrosive atmospheres).

The ambient temperature and humidity
should be the limits of the specifications.

3-1-2. Mounting methods

The EXA SC200 transmitter has universal
mounting possibilities:

- panel mounting using selftapping screws;

- surface mounting on a plate (by bolts from
the back);

- wall mounting on a bracket (e.g. thick brick
wall);

- pipe mounting using a bracket on a hori­zontal or vertical pipe (maximum diameter
50 mm);

Panel-mounting Surface mounting

Cut-out dimensions for panelmounting Dimensions

4

2 x M6 (bolts)

Unit: mm (inch)

162 (6.4)

115 (4.5)

77

180 (7)

30 (1.2)

Unit: mm (inch)

min. 203 (8)

min. 229 (9)

172 (6.77)

154(6.06)

30 (1.18)

2x ø4

IM 12D7B2-E-H

5

Universal pipe/wall mounting

Wall mounting

Pipe mounting

(vertical)

Pipe mounting

(horizontal)

2" I.D. pipe

2" I.D. pipe

115

200

70

4x ø10

2x ø6.6

56

77

IM 12D7B2-E-H

3-2-4. Access to terminal and cable

entry

1. To access terminals remove the front
cover of the EXA SC200 by releasing the
4 captive screws.

2. Pull the sensor cable into connection
space and connected the wires to the
terminals as indicated by the numbers on
the wires. Make sure all connections are
firm and do not touch each other.

3. Screw the gland securely and tighten it to
keep out moisture. DO NOT use a
wrench to tighten the nut.

4. A hose connection can be used to guide
the cables coming from an immersion fit­ting through a protective plastic tubing to
the transmitter. This adaptor has to be
bought separately.

3-2. Wiring of sensors

3-2-1. General precautions

Generally, transmission of signals from the
conductivity sensor is at a low voltage and
high impedance level. Thus care must be
taken to avoid interference.
Before connecting the sensor cable to the
transmitter make sure the next conditions
are met:

- the sensor cable is not to be mounted in
tracks together with high voltage and or
power switching cables;

- use only the standard conductivity cable
with a maximum length of 10 metre;

- mount the transmitter within the distance
of the cable.

NOTE:
The outside earth terminal should be con­nected to site ground by a large area con­ductor (e.g. a flat earth strip) for best protec­tion against interference.

3-2-2. Additional precautions for instal-

lations in hazardous areas

Make sure that the total of capacitancesand
inductances connected to the input termi­nals of the EXA SC200 do not exceed the
limits given in the certificate.This sets a limit
to the cable and extensions used.

The intrinsic safe version of the EXA SC200
instrument can be erected in Zone 1.

The sensors can be installed in Zone 0 or
Zone 1 if a safety barrier according to the
limits given in the system certificate is used.

3-2-3. Grounding the liquid

In all circumstances, the sensor side of the
measuring loop is grounded to the measu­ring liquid through one of the electrode con­tacts in the conductivity cell. The supply and
output signal are isolated to avoid uninten­tional ground loops.

6

IM 12D7B2-E-H

7

Range selection

3-2-5. Connecting diagram for sensors

2-Electrode system 4-Electrode system

TEMPERATURE
SENSOR

TEMPERATURE
SENSOR

CEL

C= 10/cm

C= 1/cm

C= 0.1/cm

C= 0.01/cm

CEL

e.g.
Use cable WU40/LH...
Max. recommended length 10 m
Use Cells SC41 or SC42

Range selection

* Use of 4-electrode

cell recommended

e.g.
Use cable WU40/LH...
Max. recommended length 10 m.
Use Cells SC49

1 µS/cm 1 mS/cm 1 S/cm 1 µS/cm 1 mS/cm 1 S/cm

C= 10/cm

C= 1/cm

*

*

IM 12D7B2-E-H

3-3. Wiring of power supply
3-3-1. General precautions

Do not activate the power supply yet.First
make sure that the DC-power supply is
according to the specifications given.
WARNING: DO NOT USE ALTERNATING
CURRENT OR MAINS POWER SUPPLY! !
The cable leading to the distributor (power
supply) or safety barrier transports power to
and output signal from the transmitter. Use
a two conductor shielded cable with a size
of at least 1.25 mm2and an outside diame­ter of 9 to 15 mm. The cable gland supplied
with the instrument accepts these diame­ters. The maximum length of the cable is
2000 metre. This ensures the minimum ope­rating voltage for the instrument.

3-3-2. Additional precautions for

installation in hazardous areas

1. Ensure that the total of capacitances

and inductances connected to the termi­nals of the EXA SC200 do not exceed the
limits given in the certificate of the safety
barrier or distributor.

2. The cable used should preferably have a

BLUE colour or marking on the outside.

3. Grounding:

• If the transmitter is mounted on a
grounded surface (e.g. a metal frame
fixed in the soil) the shield of the 2-wire
cable may NOT be connected to
ground at the distributor.

• If the transmitter is mounted on a non­conducting surface (e.g. a brick wall) it is
recommended to ground the shield of the
2-wire cable at the distributor end.

4. Installation for EEx ia (sensors in Zone 0

or 1):

Generally, the distributor with input/output
isolation has no external earth connection.If
there is an earth connection on the distribu­tor and the external connection of the trans­mitter is connected to ”protective” earth, the
shield of the 2-wire cable may NOT be con­nected to ”protective” earth at the distributor
too.

3-3-3. Access to terminal and cable

entry

The terminal strip is accessed by removing
the cover from the transmitter as was des­cribed in § 3-2-4.
Use the left-hand gland to insert the 2-wire
cable to the transmitter.
Connect the supply to the terminals marked
+, - and G as is indicated in the figures on
pages 9 & 10.

3-3-4. Power on

After all connections are made and chec­ked, the power can be switched on from the
distributor. Observe the correct activation of
the instrument at the display.If for any rea­son the display does not indicate a value,
consult the trouble shooting section.

8

IM 12D7B2-E-H

9

Wiring diagrams for power supply

General purpose design

Conductivity transmitter
EXA SC200G

NOTE:
The outside earth terminal should be connected to site ground by a large area
conductor (e.g. a flat earth strip) for best protection against interference.

Sensor

Distributor

Output Supply

Dependance of load to supply voltage

1200

1000

800

600

400

200

0

1718 20 24 40

Ohm

550

Supply voltage (V)

Load resistance (Ω)

IM 12D7B2-E-H

Wiring diagrams for hazardous areas

10

Intrinsically safe design
(CELENEC standard EEX ib [ia] IIC T4)
Conductivity transmitter
EXA SC200S

EEx ib

certified safety

barrier

Distributor

Output

Sensor

Elektronic current
Limiting barrier
Vmax: 31.5 V
lmax : 35 mA
Pmax: 0.66 W

Zener barrier with
resistor
Vmax: 28 V
lmax : 93.3 mA
Pmax: 0.66 W

Protective earth

Safe area

Protective earth

Hazardous area Supply

Zone 0 of 1 Zone 1

Eex ib

Certified distributor with

input/output

isolation

Output

Sensor

Shunt zener­barrier or
supply unit or
isolated
repeater
Vmax: 22 V
Imax : 85 mA

Protective earth

Safe areaHazardous area

Supply

Zone 0 of 1 Zone 1

Intrinsically safe design
(CELENEC standard EEX ib [ia] IIC T4)
Conductivity transmitter
EXA SC200S

IM 12D7B2-E-H

11

4. COMMISSIONING

4-1. Operations overview

MAINTENANCE
Operation by keys
through the closed cover

CAL

DISPLAY

HOLD

Calibration

Show or fix additional values

Switching hold function on/off

5-1

5-2

5-3

Adjusting the output range

Activating the hold function

Temperature compensation

4-2

4-3

4-4

Fine tuning the performance 7

OUTPUT

SET HOLD

TEMPERATURE

SERVICE

COMMISSIONING
Operation by *-key
when cover is removed

SERVICE
Operation by coded
entry from commissioning

Routine Use Chapter

Note: All levels can be protected by a 3 digit passcode. See §7-15.

IM 12D7B2-E-H

Remove cover by releasing 4 screws. Display will show * 0% Display will show *100%

12

4-2. Output range adjustment

1. Access output 2. Adjust low span value 3. Adjust high span value

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

.

*

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

µS/cm

ENT

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

mS/cm

ENT

Access commissioning menu

Adjust value for low span
Select digit to adjust
or decimal point and units

Adjust digit

Confirm adjusted value

ENT

L

*

Return to measurement

select output function
Select OUTPUT

YES

NOTE:
If the output is commissioned to be via a
table this whole item will be skipped! Default
is a linear range.

L

Adjust value for high span
Select digit to adjust
or decimal point units

Adjust digit

Confirm adjusted value

ENT

L

L

MODE

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

MODE

IM 12D7B2-E-H

13

1. What is the output range?

The display will always show the full range of
the instrument from 0-2000 mS/cm.
Maximum resolution is assured by autorang­ing, where the position of the decimal point
and the measuring units (microSiemens/­milliSiemens) are moved to best fit the actu­al value.

For control or recording the current output
can be ranged to a specific part of the total
measuring span. When selecting the
measuring range care must be taken to use
the appropriate conductivity cell. For any
given cell constant there is a defined range
of operation which should not be exceeded.

From the factory the instrument has a linear
output range 0-1 mS/cm in combination
with a cell constant C=0.1 cm

-1

.

Other linear ranges can be programmed in
this routine. It is also possible to program
non linear output ranges for specific applica­tions. These are programmed in the service
level, see sections 7-5 and 7-6.

2. Programming a linear output range

A linear output range is programmed by
entering two values:

- 0% the conductivity at the start of the
output range which corresponds
to 4 mA

- 100% the conductivity at the end of the
output range which corresponds to
20 mA.

When programming a range which does not
start at zero conductivity, take care to
respect the minimum value corresponding
to 60% of the maximum value.

3. Example

The EXA SC200 has an output table which
can be programmed to give any non-linear
output characteristic. Activation of this table
is described in §7-5. Once the table is acti­vated the linear OUTPUT routine will no lon­ger have any effect and will not be accessi­ble in the commissioning menu.
Programming of the 21 step table is descri­bed in § 7-6.

Non-linear outputs are commonly used for
measurements in pure water where high
resolution is required over a small range
combined with trend indication over a larger
range. Common forms of output for these
applications are given in §7-17.
The non-linear output can also be used to
follow a concentration curve for a specific
product. Care must be taken to ensure that
the temperature compensation is also set
up for the measured fluid under representa­tive conditions. It should also be noted that
conductivity measurements are not specific,
so it can be influenced by impurities present
or changes in the fluid composition.

4. Other possibilities

Programming a percent by weight indication
on the second display line §7-13

4-2. Output range adjustment

IM 12D7B2-E-H

14

*

HOLD = Set HOLD function Display shows actual status.

*H.OFF = HOLD not active
*H.ON = HOLD activated

Displa`y shows current setting

4-3. Set up HOLD function

1. Access HOLD routine 2. Activate HOLD function 3. Adjust value to hold

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

.

*

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

.

*

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

ENT

HOLD

.

Access commissioning menu

SELECT choice

*

Select SET HOLD
Move pointer to SET HOLD

NO

YES

Activate (de-activate) HOLD
Change setting

Conform setting

NO

YES

Select HOLD fixed or last
Change selection

Confirm selection

NO

YES

*H.FIX = Hold fixed value
*H.LST = Hold last value

Adjust fixed value
Select digit to adjust

Adjust value of digit

Accept value

Return to measurement

ENT

L

L

MODE

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

MODE

IM 12D7B2-E-H

15

1. What is HOLD?

HOLD is a function freezing the output sig­nal temporary, during normal maintenance,
preventing all sorts of alarming situations to
occur.
Two possibilities are generally used:

a .Keeping the output at the LAST value just

before the start of maintenance. This can
only be used when a recorder is connec­ted.

b. Keep the output at a preset FIXED value

which will not cause any of the alarms to
go off or any controlling action to be
taken. This is the preferred situation when
dealing with Conductivity-control sys­tems.

2. How does it work?

The HOLD-function has to be activated from
the *-menu before it can be used.

The EXA SC200 will keep the output frozen
during the following events:

- Access to the *-menu.

- Access to the calibration mode.

- Switching it from the MODE-menu.

HOLD is signalled in the display by a special
field.

The operator is prompted to switch HOLD
on or off before returning to normal mea­surement.

3. Example

In a storage tank the concentration of sodi­um hydroxide (caustic soda) has to be kept
at 5% . The mixing process is controlled by
a conductivity transmitter and electro-mag­netic valves.
During maintenance of the conductivity cell
or the transmitter the HOLD function is acti­vated to keep the mixing process from was­ting precious chemicals to the sewer.
The HOLD function is set for a fixed output
so that the dosing valves will not be activa­ted.

4. Time out

Hold will be de-activated after 20 minutes if
no key is pressed. To cancel this function
see 7-8.

4-3. Set up HOLD function

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

IM 12D7B2-E-H

16

TEMP = Temperature compensation function NaCl = Automatic temperature compensation The setting of the temperature coefficient is done

by adjusting a conductivity value, at process tem­perature, to the conductivity value that was meas­ured at reference temperature

4-4.Temperature compensation

1. Access temperature
compensation routine

2. Select automatic NaCl
temperature compensation

3 Select temperature coefficient

compensation

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

*

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

*

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

ENT

TEMP. MAN

.

.

mS/cm

Access the maintenance menu

Select temperature compensation
function

*

Select temperature compensation
routine
Move pointer to TEMP

NO

YES

Select automatic compensation
Change displayed selection

Confirm selection

NO

YES

NOTE:

1. If NaCl is chosen the temperature compensa-

tion will be according to NaCI solutions.

2. If *NaCl and *T.C. do not appear, this indicates

that Matrix compensation is selected in service
code 13.

Adjustment of the conductivity value
Select digit to adjust

Adjust manual temperature

Confirm adjusted value

ENT

L

L

Error E2 indicates that the temperature coefficient
is less than-10%/°C or more than +10%/°C.

NOTE:
Direct setting of the compensation factor is possible.
Refer to §7-12.

MODE

IM 12D7B2-E-H

17

1. Why is temperature compensation
necessary?

The conductivity of a solution is very strong­ly influenced by temperature. Typically for
every 1°C change in temperature the solu­tion conductivity will change by approxima­tely 2%.

The effect of temperature varies from one­solution to another and is determined by
several factors: solution composition,con­centration and temperature range. In very
pure water the temperature influence increa­ses dramatically with increasing purety to
approximately 6%/°C.

A coefficient (a) is used to express the
amount of temperature influence in % chan­ge in conductivity/°C.
In almost all applications this temperature
influence must be compensated before the
conductivity reading can be interpreted as a
measure of concentration or purity.

2. Automatic temperature compensa­tion with EXA SC200

From the factory EXA SC200 instruments
are calibrated with a general temperature­compensation function based on a sodium­chloride salt solution. This is suitable for
many applications and is compatible with
the compensation functions of typical labo­ratory or portable instruments.

As conductivity decreases into the range of
pure water the instrument will follow the
non-linear compensation function of neutral
NaCl solutions. In the high conductivity
region the effect of temperature decreases
and the compensation factor is decreased
too. In these extreme regions the tempera­ture compensation factor is calculated with
a square equation.

A temperature compensation factor is de­rived from the following equation:

α

= Temperature compensation factor (in

%/°C)
T = Measured temperature (°C)
Kt= Conductivity at T
T

ref

= Reference temperature (25°C)

K

ref

= Conductivity at T

ref

3. Manual setting of temperature com­pensation with EXA SC200

If the general compensation function is
found to be inaccurate for the sample in
question, the instrument can be set manual­ly for a linear factor on site to match the
application.

The procedure is as follows:

1. Take a representative sample of the pro­cess liquid during operation.

2. Heat or cool this sample to the reference
temperature of the instrument (usually
25°C). Note: see §7-4.

3. Measure the conductivity of the solution
with the SC200 and note the reading of
the display.

4. Bring the sample to the typical process
temperature. (Check the temperature with
the display routine.)

5. Adjust the reading of the display to the
previously noted value at the reference
temperature.

6. Check that the temperature compensa­tion factor has been changed (from the
display routine).

7. Insert the conductivity cell into the pro­cess again

4. Other possibilities

Manual temperature coefficient §7-12.

4-4. Temperature compensation

Kt- K

ref

x 100

α=

X

T - T

ref

x K

ref

IM 12D7B2-E-H

4-5. Sensor selection and diagnostics

4-5-1. General remarks

The EXA SC200 continuous sensor diagnos­tics can lead to the indication of faults due
to the fouling of the connected sensor. The
fault will be indicated with a signal field on
the display and (if activated) by a 22 mA sig­nal. The selection of the correct conductivity
cell with the suitable cell constant is explai­ned in the next section.

4-5-2. Selecting a conductivity cell

First select the range limits for the EXA in­strument.
For conductivity values below 1 µS/cm the
only choice is a cell with cellconstant 0.01
cm-1. From 1 µs/cm up to 10 mS/cm a cell­with cellconstant 0.1 cm-1can be used. A
cellconstant of 1 cm-1is used between 10
µS/cm up to 100 mS/cm. The cell with cell­constant 10 cm-1is used from 100 µS/cm to
1 S/cm. All these values refer to the actual
measured values at the operating tempera­ture.
Above 20 mS/cm with C=1 cm-1and 200
mS/cm with C=10 cm-14-electrode cells
are advised.

Yokogawa delivers cells from a choice of
chemically resistant materials like stainless
steel, epoxy resin, PTFE and PVDF.

The cell determines the principle used to
measure the conductivity: there is a distinc­tion between 2-electrodes and 4-electrodes
cells.
The selection of 2 or 4 electrode measuring
principle is from the service level §7-9.

4-5-3. Selecting a different cell-con­stant

The EXA SC200 can be programmed to ac­cept any cell with a cell-constant between

0.01 and 50/cm. The adjustment of the cell­constant must be executed from the service
level §7-7.

4-5-4. Integral temperature sensor

The factory setting for the temperature sen­sor is a Pt-1000 element. To get a different
temperature setting the service level setting
at § 7-4 is used.
A separate temperature sensor can be con­nected, if no integral temperature element is
present in the conductivity cell.
Choose a Ni-100, NTC or Pt-1000 sensor
to get the correct temperature reading.

4-5-5. Sensor diagnostics and related-

error messages

The check for polarisation of the electrodes
is only working correctly when the cell-con­stant has been chosen to match the measu­ring range. The check is automatically
switched off when the 4-electrode measu­ring principle is selected. The check can
manually be switched on or off: refer to

§7-14. The factory setting for the polarisa­tion check is off.

18

IM 12D7B2-E-H

19

IM 12D7B2-E-H

20

CALIB = Calibration

START = Start calibration CAL.END = End of calibration session

5. MAINTENANCE
5-1. Calibration

1. Access calibration routine 2. Adjust value 3. End calibration

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

µS/cm

MODE

.

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

ENT

µS/cm

MODE

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

µS/cm

MODE

.

Access maintenance mode

Select calibration

Select manual calibration
Move pointer to display

NO

YES

End calibration
End calibration and return to
measurement

Continue routine to calibrate second
point (repeat step 2)

YES

NO

MODE

Conform start of adjustment

YES

Select digit to adjust

Adjust value

Conform adjusted value

ENT

L

L

Adjust process value to previously determined
value (e.g. from hand-held conductivity-meter)

Error E3 indicates that the calibration value is
deviating more than 20% from the originally meas­ured value.

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

MODE

IM 12D7B2-E-H

21

1. When is calibration necessary?

Calibration of conductivity instruments is not
normally required since conductivity cells are
manufactured within controlled tolerances
and do not alter in use.

If the cell has been severely fouled or sub­ject to abrasion (possibly during cleaning) it
may be necessary to calibrate.

Alternatively calibration may be carried out
with a simulator to check the electronics
only.

2. How is calibration done?

Calibration is carried out by measuring a
solution which has a known conductivity
and adjusting the instrument to show the
correct conductivity value.

Calibration solutions can be made up in the
laboratory. A solution of salt is made with
precise concentration. Temperature is stabi­lised to the reference temperature of the in­strument (usually 25°C). The conductivity of
the solution is taken from tables.

Alternatively the instrument may be calibra­ted in an unspecified solution against a
standard instrument. Here care should be
taken to make measurement at the refe­rence temperature since differences in the
type of temperature compensation of the
instruments may cause an error.

3. Typical calibration solutions

The table below shows typical conductivity
values for solutions which may be made up
in the laboratory.

Table for NaCI at 25°C

5-1. Calibration

% weight mg/kg Conductivity

00.001 10 021.40 µS/cm

00.003 30 064.00 µS/cm

00.005 50 106.00 µS/cm

00.01 100 210.00 µS/cm

00.03 300 617.00 µS/cm

00.05 500 001.03 mS/cm

00.1 1000 001.99 mS/cm

00.3 3000 005.69 mS/cm

00.5 5000 009.48 mS/cm
01 10000 017.60 mS/cm
03 30000 048.60 mS/cm
05 50000 081.00 mS/cm

10 100000 140.00 mS/cm

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

IM 12D7B2-E-H

22

5-2. Selecting a value to display

DISP = DISPLAY routine

The second line of the display will show the possi­bilities

The second line of the display will show the possi­bilities

1. Access display routine 2. Read data 3. Reprogram data display

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

MODE

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

MODE

.

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

MODE

.

Access maintenance mode

Select Display routine

Select display
Move pointer to DISPLAY

NO

YES

Read data
To read values only

Parameter Unit

- Temperature ˚C/˚F

- Output signall mA

- % by weight %
C.C - Cell constant cm-1
T.R. - Reference

temperature ˚C/˚F
NaCl/jjj - Temperature
T.C Compensation coefficient

standard/manual

%/˚C

REL - software release

Return to measure

NO

MODE

Reprogram data display
Move to desired value for display

Parameter Unit

- Temperature ˚C/˚F

- Output signal mA

- % by weight %

C.C - Cell constant cm

-1

T.R. - Reference

temperature ˚C/˚F
NaCl/jjj - Temperature
T.C Compensation coefficient

standard/manual

%/˚C

REL - software release

To select a value for permanent dis­play during measurement

NO

YES

MODE

MODE

IM 12D7B2-E-H

23

1. What is the display routine?

The second line in the display is intended to
be used to:

- Show actual status

- Show messages

- Show errors

When delivered from the factory the
EXASC200 shows the temperature on the
second line.
You can make the instrument show a diffe­rent parameter on the second line by selec­ting it from the list at right.

2. What can you read?

Temperature is an actual value.
Output is an actual value.
Percent by weight is an actual value.
Cell constant is programmed.
Reference temperature is programmed.
NaCl or temperature coefficient is program­med.

The choice of temperature units is done
from the Service level.

Error messages have priority over other
messages.

Note: Percent by weight is only visible when
activated from the service level §7-13.

3. Example

To check the value of the output signal
(4...20 mA) it is displayed on the second
line.

Measuring range 0...100 µS/cm
Output signal 4...20 mA

Process value 60 µS/cm
Output value 13.6 mA

When the second line is changed to display
output the current signal is visible all the
time.

Whenever HOLD is activated the value on
the display is frozen to the programmed
value (using the FIXED setting).
Pressing MODE will take you back to
measuring and the temperature will show
again.

5-2. Selecting a value to display

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

IM 12D7B2-E-H

24

5-3. Use of HOLD function

HOLD = HOLD output function

Display will blink HOLD and YES/NO

1. Access hold 2. Switch hold on/off

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

MODE

MEASURE
CAL
DISPLAY.
HOLD

YES

NO

YES

NO

MODE

MODE

HOLD

Access maintenance mode

Select HOLD function

Move pointer to HOLD

Select HOLD function
Select HOLD

NO

NO

Switch hold OFF

Switch hold ON

NO

YES

MODE

NOTE: This function can only be used if activated
during commissioning (see chapter 4-3).

HOLD in left top of display is switched

MODE

IM 12D7B2-E-H

25

1. What is HOLD?

Hold is a function which freezes the output
signal temporarily, it is normally used during
maintenance when the cell is removed from
the measured solution to prevent unwanted
controller reaction.

The HOLD function must be commissioned
from the programming menu before it can
be switched on or off. See commissioning
the hold function for more details.

Note:
AUTO RETURN will switch off HOLD after
20 minutes, see § 7-8.

2. How does it work?

From this level the HOLD function can only
be switched ON or OFF.
HOLD is switched on when you press YES
when HOLD and YES/NO are blinking.
When you press NO hold will be switched
off
A flag is kept in memory and an indication is
made in the upper left corner of the display
field.

The HOLD function only influences the out­put signal, no other functions are influenced.

The operator is prompted to switch HOLD
on or off after having performed a mainte­nance function.

3. Example

During the transfer of cleaning liquid into a
batch reactor with a conductivity-control
system, the HOLD function is switched ON
to prevent the controlling instruments from
running wild.
After cleaning has ceased and the new
batch has been started HOLD is switched
OFF again and conductivity control resu­mes.

5-3. Use of HOLD function

IM 12D7B2-E-H

6-1. Introduction

The EXA SC200 microprocessor based
conductivity analyser continuously monitors
the condition of all key components of the
measuring system to ensure that measure­ment is dependable. If a fault is detected
this is immediately signalled. Errors are
shown on the display with a code.
The following table shows the errors which
can be detected and gives information to
help locate the fault or identify the error.
Faults detected whilst the instrument is on
line can also be signalled by a (temporary)
high output signal (22 mA).

6-2. Self diagnostics of the conductivity

cell

During measurement the instrument adjusts
the measuring frequency to give the best
conditions for the actual value being meas­ured. At low conductivity there is risk of
error due to capacitive effects in the cable
and cell. These are reduced by using a low
measuring frequency. At high conductivity
these capacitive effects become negliable
and errors are more likely to be caused by
polarisation or fouling of the cell. These
errors are reduced by increasing the measu­ring frequency.

At all values the instrument checks the sig­nal from the cell to search for distortion
which is typical of capacitive or polarisation
errors. If there is a problem with the installa­tion or the cell becomes fouled this will trig­ger an error message on the display possi­bly accompanied by a fault signal through a
(temporary) high output current (22 mA).

6-3. Self diagnostics of the temperature

sensor

The temperature sensor, which is normally
built into the conductivity cell, is checked to
detect damage or faulty connections.

NOTE:
A temperature fault may be caused by
incorrect programming of the temperature
element!

6-4. Self diagnostics of the electronics

The microprocessor operation is checked
by a watchdog which initiates an electronic
reset if the normal function suffers severe
interference. During reset the instrument
checks the program and all stored data. If a
fault is then detected an alarm is given.

6-5. Checking during operation

Whenever the instrument is being program­med or calibrated, data is checked and an
error is shown when appropriate.
Should this occur the new data is rejected
and the instrument continues to work with
the previous settings.

26

6. TROUBLE SHOOTING

IM 12D7B2-E-H

27

6-6. Error messages and explanation

Code Error description Possible cause Suggested remedy

E1* Faulty signal from conductivity cell Polarisation Check cell is correct for range

Cell is fouled Clean cell

E2 Wrong temperature coefficient during Incorrect data entered Repeat temperature calibration

calibration

E3 Calibration out of limits Calibration value deviates more than Check cell, connections or reference

20%

E5* Conductivity too high Measurement is out of range Check cell range, reprogram range
E6* Conductivity too low Measurement is out of range Check cell range, reprogram range

E7* Temperature too high Wrong temperature sensor selected Program sensor type

Fault in connections Check connections

E8* Temperature too low Wrong temperature sensor selected Program sensor type

Fault in connections Check connections

E10* EEPROM write failure Fault in electronics Call yourYOKOGAWA service

organisation

E15 Temperature correction Fault in cable or wrong Check connections or program

outside limits (> 5Ω) temperature sensor selected correct sensor type

E17 Output span too small 0% range value set too high Program value <60% of high range
E18 Output table makes no sense Table changes from ascending to Check programming of table

descending or vice versa

E19 Programmed value not accepted Values not acceptable Reprogram with new values
E20* Data lost Data, including initial setting, lost Call your YOKOGAWA service

organisation

* These errors will trigger the FAIL-status.

IM 12D7B2-E-H

7. SERVICE MODE

7-1. Introduction

Generally speaking their is no necessity to
adjust the settings of the service section All
parameters are pre-programmed to values
(so-called defaults) enabling you to start
working immediately.

The advanced functions available through
this section are only needed in some speci­fic applications. This fine-tuning of the in­strument gives a superior performance over
conventional 2-wire instruments.

If a function has to be adjusted it is called up
with the code mentioned. Having selected
the code then give you the possibility to
either activate or adjust the values for this
function. After this you will return to the
entry point to make other adjustments or go
back to the measuring status.

If errors are made during the programming
process, these will be indicated, no action
will be taken and you can start the program­ming again.

28

Code Routine Use Chapter

01 Temperature sensors and units Select sensor type 7-3

Select °C or °F
02 Reference temperature Adjust value 7-4
03 Output table or linear Select which to use 7-5
04 Program output table Set values in table 7-6
05 Cell constant Adjust cell-constant 7-7 +10-1
06 Auto return function Switch on or off 7-8
07 Measuring principle Select 2 or 4 electrode 7-9
08 Temperature adjust Correct cable error 7-10
09 Signal errors or output Switch on or off 7-11
10 Temperature compensation factor Adjust factor 7-12
11 %-indication on second Switch on or off and 7-13

display line Set values
12 Polarisation check Switch on or off 7-14
13 Matrix compensation Select 5x5 matrix compensation 10-2
14 Matrix temperature Set temperatures for user matrix 10-3

compensation range
15-19 Matrix data Set data for user matrix 10-4
20 “Soft”/“hard” fail situation Select “soft” or “hard” fail 10-5

message per fail code
21 E6-fail message Switch on or off 10-6
33 Passcode activation Protecting levels 7-15
55 Restore defaults Erase values 7-16

IM 12D7B2-E-H

29

ESCAPE TO MEASURE can be used at any stage to abort operation. WARNING: If the HOLD function is activated the instrument returns with the question HOLD (flashing);
answer YES or NO or MODE again to return to measurement.

7-2. Access to service settings

*SERV = Service settings

Display will show *CODE Display shows current setting

Values adjusted access to individual routine
description

1. Access service 2. Enter code to select
required function

3. Adjust setting
(see individual routines)

OUTPUT
SET HOLD
TEMPERATURE
SERVICE

YES

NO

YES

NO

MODE

*

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

ENT

OUTPUT
SET HOLD
TEMP.
SERVICE

ENT

ENT

.

.

Access commissioning menu

Select SERVICE

*

Select service function
Move pointer to service

NO

YES

Enter access code to select routine
Select digit to adjust

Adjust code for entry

Confirm choice

ENT

L

L

Adjust settings
Select digit to adjust

Adjust value

Confirm adjusted value

ENT

L

L

Return to measure

MODE

MODE

X.X

0. Temperature sensor = Pt-1000

1. Tempersture sensor = Ni-100

2. NTC sensor
.0 Temperature displayed in ˚C

.1 Temperature displayed in ˚F

IM 12D7B2-E-H

30

7-3. Temperature sensors and units

ACCESS-CODE: 01 (see § 7-2)
DISPLAY : *T.CODE

Adjustment (X.X)

7-4. Reference temperature

ACCESS-CODE : 02 (see § 7-2)
DISPLAY : *T.R. ˚C or *T.R. ˚F

Adjustment : Adjust the value for the

reference temperature
used in the calculations.
Normally this value will be
25˚C.

Explanation:

The code for the temperature units influen­ces the temperature indication on the dis­play only. Default value is ˚C.
The indication here determines which tem­perature sensor is connected to the instru­ment. Check what sensor will be used in
your plant and set the correct number for it.
Default value is Pt-1000 for Yokogawa sen-

sors, type SC42-.....

Default: ˚C

Explanation:

All measured values are compensated for
temperature to refer to comparable values
at 25˚C. This temperature is easily produced
at laboratory conditions and most literature
data use this temperature. In exceptional
cases it is possible to use a different refe­rence temperature in combination with a
programmed temperature coefficient (e.g.
Sulfuric acid measurement).

Default: 25˚C

7-5 Output code selection

ACCESS-CODE : 03 (see § 7-2 )
DISPLAY : *TABLE

Adjustment : 0=Linear range only

1=Output table with 20
steps

Explanation:

As a default a linear output is set and only
0% and 100% can be adjusted from the
commissioning output function.
When an output table is programmed by
setting a 1, the table can be programmed at
CODE 04.
Otherwise CODE 04 will have no effect. See
the entry at the next CODE.

IM 12D7B2-E-H

31

7-6. Output table for non-linear range

ACCESS-CODE : 04 (see §7-2)
DISPLAY : 0% to 100%

Adjustment :

A 21 step table can be
programmed from this
entry ONLY IF it was set
in the previous CODE 03.
It is possible to set up a
bi-linear, semi-logarith­mic or hyperbolic scale
to cope with retro fitting
on existing installations.
Also linear output to con­centration related curves
can be programmed.

Explanation:

First you will be presented with the question
YES/NO to give the opportunity to skip valu­es from the table. To get a 10 step table you
would skip every other value and only ans­wer YES to enter a value. The instrument
uses interpolation between entered values.
Press NO to skip values. Press YES to
adjust value. Now adjust the value by pres­sing > and ^.
The units can be adjusted as well as the
decimal point position.
Examples are mentioned in §7-17.
Other possibilities: programming ”% by
weight” indication on second display line:
refer to §7-13.

Percentage of mA-output range versus
percentage of conductivity range.

Examples:
A = bilinear
B = hyperbolic (2 decades)
C = logarithmic (2 decades)
D =linear

NOTE:
Curves are not selectable, but can be pro­grammed from the tables at right.

Example of output tables

bi-lin = bi-lineair over 2 decades
log 2 = logarithmic over 2 decades
log 3 = logarithmic over 3 decades
hyp 2 = hyperbolic over 2 decades
hyp 3 = hyperbolic over 3 decades

NOTE:
Multiply the values from the table with
appropriate factors to get the end-scale
value you want.

Special concentration tables can be pro­grammed by the user.

mA-output range

% of conductivity range

Output bi-lin log 2 log 3 hyp 2 hyp 3

0% 0.0 1.0 0.10 1.00 0.10
5% 1.0 1.3 0.14 1.20 0.27
10% 2.0 1.6 0.20 1.82 0.43
15% 3.0 2.0 0.28 1.90 0.61
20% 4.0 2.5 0.40 2.00 0.83
25% 5.0 3.2 0.56 3.75 1.10
30% 6.0 4.0 0.79 4.80 1.36
35% 7.0 5.0 1.12 5.92 1.68
40% 8.0 6.3 1.58 7.00 2.05
45% 9.0 7.9 2.24 8.31 2.49
50% 10.0 10.0 3.16 10.00 3.00
55% 20.0 12.6 4.47 11.85 3.66
60% 30.0 15.8 6.31 14.00 4.33
65% 40.0 20.0 8.91 16.65 5.22
70% 50.0 25.1 12.6 19.50 6.80
75% 60.0 31.6 17.8 23.80 8.25
80% 70.0 39.8 25.1 29.55 11.0
85% 80.0 50.1 35.5 36.70 14.8
90% 90.0 63.1 50.1 48.50 21.8
95% 100.0 79.4 70.8 68.60 36.5
100% 110.0 100.0 100.0 100.00 100.0

X
0 OFF

1 ON

IM 12D7B2-E-H

32

7-7. Cell constant adjustment

ACCESS-CODE : 05 (see §7-2)
DISPLAY : *CELL.C

Adjustment : Adjust the value to the

cell-constant used with
your instrument.
Values between 0.01 and
50/cm can be program­med.

Explanation:

Every conductivity cell has a cell-constant,
which can be indicated on the outside of the
body. Sometimes the cell-constant can be
indicated in the type-number of the sensor.
Yokogawa produces several models with
cell-constants of 0.01, 0. 1, 1 and 10/cm.
For accurate measurements the cell-con­stant can be determined in a laboratory test.

Default: 0.1 cm

-l

7-8. Auto return function

ACCESS-CODE : 06 (see §7-2)
DISPLAY : *RET

Adjustment: X

Explanation

As a safeguard against long maintenance
jobs or inadvertently pushing a button it is
possible to let the system return to its nor­mal function of measurement when no keys
are pushed for 10 minutes.

Default: Auto return on

7-9. Measuring principle

ACCESS-CODE : 07 (see §7-2)
DISPLAY :*4ELEC

Adjustment : Select the measuring

principle of the transmit­ter.

X
0 2-electrode principle

1 4-electrode principle

Automatic return to measure after 10
minutes.

Explanation:

Select the principle to cooperate with the
measuring sensor.
The conductivity cell determines which prin­ciple can be used.
The 4-electrode principle is used for the
high conductivity values in general.

Default: 2-electrode principle

X.X
0 OFF
1 ON = 22 mA steady signal on

fault.

2 ON = 22 mA pulse during

30s at start of fault
then normal output.

IM 12D7B2-E-H

33

7-10. Temperature sensor adjustment

ACCESS-CODE :08 (see § 7-2)
DISPLAY :*T.ADJ

Adjustment :Adjust the value of the

indicated temperature
(°C/°F) to that of the
actual temperature.

Explanation:

The temperature measurement is a two wire
resistance measurement. In this kind of
measurement the length of the connecting
cable can influence the accuracy of the tem­perature indication. To compensate for the
extra resistance of the cable up to 5Ω can
be calibrated. Connect the correct tempera­ture sensor to the EXA instrument and insert
it in a stable temperature bath of a known
value.
Check the temperature indicated at this set­ting in °C or °F and adjust the value if
necessary.
Now the EXA transmitter has been calibra­ted to compensate for the cable resistance.

7-11. Signalling of fail condition

ACCESS-CODE : 09 (see §7-2)
DISPLAY : *BURN

Adjustment : X.X

Explanation:

Besides an indication at the display in the
field, sometimes an indication of errors in the
control room is also necessary. This is possi­ble by sending a special signal over the 2­wire connection to the receiving instrument.
A signal of 22 mA is used, because it is out­side the normal analogue range of 4 to 20
mA. If at the receiving end an alarm is set to
the value represented by 22 mA, it is obvious
that the proper action can be taken from the
control room too. The signal uses the same
convention as used in thermocouple indica­tions for detecting break of the sensor (burn­out).

Default: 0 = OFF

7-12. Temperature compensation

coefficient adjustment

ACCESS-CODE : 10 (see § 7-2)
DISPLAY : *T.C.

Adjustment : Adjust the value of the

manually set compensa­tion factor

NOTE:
Access to this routine is only possible when
manually set temperature compensation
factor (α) is selected in §4-4.

Explanation:

In addition to the procedure described in

§4-4 it is possible to adjust the compenstion

factor directly. If the compensation factor of
the sample liquid is known from laboratory
experiments or has been previously determi­ned, it can be introduced here.
Adjust the value between -10.00 to -10.00
% per °C. In combination with the reference
temperature setting at §7-4 a linear com­pensation function is obtained, suitable for
all kind of chemical solutions.

Kt- K

ref

x 100

α =

X

T - T

ref

x K

ref

Default: skipped, compensation for NaCI
is automatic.

X
0 OFF

1 ON

IM 12D7B2-E-H

34

7-13. Percent by weight indication on

second display line

ACCESS-CODE : 11 (see § 7-2)
DISPLAY : *%

Adjustment:(X)

Select the possibility to display % by weight
on the second display line. When %
indication is activated (Select 1) the display
range can be adjusted:
*0%: Adjust low span display value
*100% Adjust high span display value

Explanation:

In case a conductivity measurement is used
for concentration monitoring it can be con­venient to link the measured conductivity
value to a % by weight concentration value.
A linear concentration indication in % units is
programmed by entering two values.

- X in 3 digits corresponds to 0% of the
output value (= 4 mA)

- Y in 3 digits corresponds to 100% of the
output value (= 20 mA)

Example:

0% output is 93.0% by weight

100% output is 99.0% by weight

The instrument uses interpolation between
the entered values. As the relation between
percent by weight concentration and con­ductivity is not linear in most cases, the pos­sibility to linearize the output to concentra­tion units can be used. Refer to §7-5 and

§7-6. The instrument becomes a concentra­tion meter by output function and (second)
display (line) based on a conductivity mea­surement.

Default: OFF

7-14. Polarisation check

ACCESS-CODE : 12 (see §7-2)
DISPLAY : *POL.CK

Adjustment: (X)

Generation of the fault E1 can be switched
off.

Explanation:

The EXA SC200 normally checks the signal
from the cell to search for distortion typical
of capacitive or polarisation errors. If there is
a problem with the installation or the cell
becomes fouled this will trigger the E1 fault
signal.
In some installations this error detecting can
cause unwanted signals during operation.
Then the possibility to disable this check will
be used.

Note: When 4-electrode measurement is
chosen this checking is not performed.

Default: OFF

X
0 OFF

1 ON

IM 12D7B2-E-H

35

7-15. Passcode protection by three digit

code

ACCESS-CODE : 33 (see § 7-2)
DISPLAY : *PASS

Adjustment(X.X.X)

0.X.X Protection on Maintenance level inactive
X.0.X. Protection on Commissioning level inactive
X.X.0 Protection on Service level inactive

#.X.X Protection on Maintenance level activated
X.#.X Protection on Commissioning level activated
X.X.# Protection on Service level activated

Note: # can be a digit from 1 to 9, and it will
give a protection according to the schema­tic below of the programmed level.
0 = No passcode 5 = Passcode is 123
1 = Passcode is 111 6 = Passcode is 957
2 = Passcode is 333 7 = Passcode is 331
3 = Passcode is 777 8 = Passcode is 546
4 = Passcode is 888 9 = Passcode is 847

Explanation:

In some cases a protection of operation
level is wanted. In this way unauthorized
access to any of the 3 levels can be blocked
by a simple passcode. When a passcode is
selected for an operation level, access to
that level can only be obtained after ente­ring the passcode. The display will show a
message *PASS* to indicate the entry of the
passcode.

NOTE:
For the Maintenance and Commissioning
level the passcode entry is always requested
when entering from the measure mode.

- For the Service level the passcode entry is
requested after pushing the YES-key.

- When the Service level protection is activa­ted, the passcode cannot be changed by
unauthorized persons.

Default: 0.0.0.

No Passcode protection.

7-16. Restore default setting

ACCESS-CODE : 55 (see §7-2)
DISPLAY : ERASE

Adjustment: YES Erase all program-

med values and
replace them by
defaults.

NO Keep all program-

med values as befo­re.

Explanation:

This entry is provided to make it possible to
start from the default values given by
Yokogawa and thus erase all previously pro­grammed information.

WARNING:
Do not use this code without proper authori­ty as all settings and programmed functions
will be lost!!

WARNING

Do not enter service codes that are
not mentioned in this booklet.

11 12 14 13 17 15 16

G - +

IM 12D7B2-E-H

36

8. CLASSIFICATION

1 conductivity sensor with integral SC41-SP34

temperature sensor such as (but SC49-FP08
not limited to) SC41-SP24

SC41-EP14
SC41-EP04

These are all passive sensor to be regarded as "simple apparatus"
i.e. devices which coply with clause 1.3 of EN 50014.

SC 200 S
Vout = 14.4 V max.
Iout = 72.8 mA max.
C ext = 1300 nF max
L ext = 8.0 mH max.

BASEEFA Nr. Ex 89C2379

connecting cables
such as (but not limited to):
WU40-LH18 WU40-LH2
WU40-LH5

Certified Barrier with electronic current limitation and the fllowing characteristics:
V max. out = 31.5 V, Imax. out = 35 mA, P max. out = 1.1 W
type : Yokogawa Bard 400 (BASEEFA Cert. Ex 84B2257x)

Any shunt zenerdiode safety barrier certified by BASEEFA or any EEC approeved certification body to [EEx ia] II C or [EEx ib] ii C where the
output current is limited by a resistor "R" directly in the output line such as that Imax.out = Vmax.out/R and not exceeding the following char­acteristics:
Vmax.out = 28 V; Imax.out = 93.3 mA and Pmax.out = 8.66 W.
such as (but not limited to):
type: MTL 728

MTL 788 (BASEEFA Cert. Ex 832452)
MTL 788 R
Stahl 8981/31-280/085/00 (P.T.B. Cert. Ex-78/2007X)

any shunt zenerdiode safety barrier or supply unit or isolated repeater certified by BASEEFA or any EEC approevd certification body to [EEx ib]
ii C or [EEx ib] ii C where the output current is limited in a different way and not exceeding the following characteristics:
Vmax.out = 22 V and Imax.out = 85 mA
such as (but noy limited to):
type: Camille Bauer Sineax 84-2B1-511

Sineax 89-2B1-511

(P.T.B. Cert. Ex-81/2044X)

NON HAZARDOUS AREA

or

or

ZONE 1

or

ZONE 2

SYSTEM CERTIFICATE
EXA200 INSTRUMENTS
BASEEFA NO Ex 892380

8-1. Cenelec

Ex-classification:
EEx ib [ia] IIC T4
Zone 0 or 1 Zone 1

SC 200 S
V

out

= 14.4 V max.

I

out

= 129 mA max.

C ext = 1 µF max
L ext = 2.3 mH max.

31.5 Vmax
4-20 mA

+
–

•

•

11 12 14 13 17 15 16

IM 12D7B2-E-H

37

8-2. FM

connecting cables
such as (but not limited to):
WU40-LH18 WU40-LH2
WU40-LH5
10 meter Maximum

HAZARDOUS LOCATION

FMRC-Approved Barrier

To be installed in accordance with ANSI/RP 12.6 and NEC requirements

Maximum safe area voltage should not exceed 250 V

RMS

NON HAZARDOUS LOCATION

Class I, Division I, Groups ABCD
Vmax = 31.5 V
Imax = 93.3 mA
Ci = 5 nF
Li = 16.5 uH

ControlDrawing for EXA 200 instruments

1 conductivity sensor with integral SC41-SP34

temperature sensor such as (but SC49-FP08
not limited to) SC41-SP24

SC41-EP14
SC41-EP04

These are all passive sensor to be regarded as "simple apparatus"
i.e. devices which do neither store nor generate voltage over 1.2 V,
currents over 0.1 A, power over 25 W or energy over 20 mJ

IM 12D7B2-E-H

38

The EXA SC200 can be used for both con­ductivity and resistivity measurement. As
delivered the instrument is set for conducti­vity measurement.

9-1. How to change from conductivity to

resistivity measurement

- Remove the cover after loosening the 4
screws. Now you have access to the Dis­play Board.

- Loosen the 4 screws that hold this board
in place and remove it from the enclosure.

- On the upper back side of the Display
Board are 5 blue jumpers. Change the
spring jumper as shown in the figure.
Make sure that center contact spring is
securely hold to have good contact.

Within 15 seconds after the jumper change,
the EXA SC200 will automatically load de­fault data for resistivity measurement.

The SC200 transmitter can be reassembled
now, following the opposite sequence as
described above.

9-2.Resistivity measurement

As a resistivity measuring transmitter the
EXA SC200 has the same function as
described earlier in this manual.

The units mS/cm and µS/cm are replaced
by kΩ.cm and MΩ.cm for resistivity meas­urement. If no unit is shown the unit is Ω.cm
and can be changed in kΩ.cm by the key

if the “.” is flashing. See range adjustment in

section 4-2.

9. CHANGE FROM CONDUCTIVITY TO

RESISTIVITY MEASUREMENT

from

position for conductivity
measurement

to

position for resistivity
measurement

9-3.Maintenance of the transmitter

Calibration of the resistivity transmitter is
done in the same way as described in sec­tion 5-1.
The calibration values can be calculated as
follows:
kΩ.cm = 1000 µS/cm
Ω.cm = 1000 mS/cm

Example:

The 0.001 % NaCI-solution has a conducti­vity value of 21.4 µS/cm. In resistivity mode
the value is 1000/21.4 = 46.7 kΩ.cm.

IM 12D7B2-E-H

39

10. SOFTWARE VERSION 3.0 COM­PARED TO VERSIONS 1* AND 2*.

In 1994 the software of EXA SC200 has un­dergone a major update as result of user
feedback. New features are made accessi­ble by additional Service Codes to avoid
programming conflicts with users of pre­vious versions.

10-2.Matrix compensation

ACCESS CODE : 13
Display : *MATR

Adjustment:
0 Only linear compensation (see access

code 10)
1 HCI pure water (0 - 100 °C)/CATION
2 Ammonia
3 Morpholine in pure water
4 Hydrochloric Acid (1-5%)
5 Nitric Acid (1-5%)
9

User adjustable matrix (see access code 15

NOTE:
Access to this routine is only possible when
manually set temperature compensation
factor (α) is selected in §4-4.

Explanation:

The SC200 is equiped with a matrix type
algorithm for accurate temperature compen­sation in various applications. Select the
range as close as possible to the actual
temperature/concentration range. The
SC200 will compensate by interpolation and
extrapolation. Consequently, there is no
need for a 100 % coverage.
If 9 is selected the temperature compensa­tion range for the user adjustable matrix can
be set in access code 15. In access codes
16 and 19 the specific conductivity values at
5 different temperatures is entered.

The new features are:

10-1. Cell constant

ACCESS-CODE : 05
DISPLAY : 1.00xC
Adjustments:

1. Select multiplying factor

2. Adjust the required cell constant

1. Select multiplying factor with keys
YES and NO.

2. With keys > and ^ any cell con­stant between 0.01 and 50.0 cm

-1

can be selected.

Explanation:

1. Multiplying factor

- The multiplying factor is confirmed after

pressing the YES key.

- Change multiplying factor to 1.0-10­10-0.01-0.1-1.0 by pressing NO key
and confirm selection with YES key.

2. The value of the cell constant is indicated

in the specifications of the cell and/or on its
identification plate.

Adjust the required value of the cell after
pressing the YES key to confirm the multi­plying factor.
Select the digit to adjust with key > (digit
flashes).
With ^ key the value of the selected digit
can be changed.

Example: Cell constant = 0.00985

a. Select multiplying factor 0.01
b. Adjust the value to .985

IM 12D7B2-E-H

40

10-3. Matrix temperature compensation

range

ACCESS CODE : 14
Display : *T1 °C

Adjustment: : After selecting 9 in Ac-

cess Code 13 the begin­and endscale value of
temperature compensa­tion range of the users
matrix can be adjusted
using the keys . and ^.

Explanation:

In service codes 14 to 18 the SC200 trans­mitter can be fingerprinted to one particular
application.
In access code 13 you have the possibility
to adjust the compensation range.
After having access to this routine adjust the
beginscale value of the compensation
range. After entering the beginscale value
the display indicates T5 °C and the endscale
value can be adjusted. The temperatures
T2, T3 and T4 are found proportionally.
Notes:

1. In defining the temperature compensation
range, it is important to select T1 and T5 in
such a way that the 5 reference temperatu­res are user friendly.
Example: T1 = 0 and T5 = 80 °C gives ref-

erence temperatures of 0, 20, 40,
60 and 80 °C.

2. The minimum span for the range is 50
°C(Error code 17 indicates a temperature
range of less than 50 °C).

10-4. Matrix data

ACCESS CODE : 15,16,17,18,19
Display : *L1*T1

Adjustment : After adjusting the range

in access code 14 it is
necessary to fill the ma­trix.

Explanation:

In these access codes the specific conducti­vity values can be entered for 5 different
concentrations of the process liquid; each
one in one specific access code (15 to 19).
Adjust the conductivity value of the first solu­tion at temperature T1 using keys > and ^.
Confirm the adjustment by pressing the ENT
key. The display indication changes to “L1
xT2”. Now the conductivity value at tempe­rature T2 can be adjusted. Continue this
process until “SERV” is displayed and
adjustment is finished.
Repeat the procedures for solutions 2 to 4
in access codes 16 to 19.

NOTES:

1. Use the table on page 42 to record your
pro-grammed values. It will make pro­gramming easy for duplicate systems or
in case of data loss.

2. Each matrix column has to increase in con­ductivity value:
L1 .Tx<L2.Tx<L3.Tx<L4.Tx<L5.Tx

3. Error code E4 occurs when two standard
solutions have identical conductivity
values at the same temperature within the
temperature range.

IM 12D7B2-E-H

41

10-5. Selection between ”soft” or ”hard”

FAIL Situations

ACCESS CODE : 20
Display : *ERR.01

Adjustment:
NO Error 01 is skipped; next error is

shown

YES 0 = Soft alarm

1 = Hard alarm
Pressing ENTER confirms the selec­tion

Explanation:

As described in chapter 6, the error codes
marked with an asterisk(*) normally will trig­ger a number of actions.
If soft alarm action is selected, the FAIL
message flag is flashing. The output func­tions will not go into BURN OUT position
and the contact outputs continue to opera­te.
If hard alarm function is selected, the output
goes into BURN OUT signal if programmed
that way in Access Code 09: and the FAIL
flag is shown in the display.

10-6. Selection between yes or no E6

Fail-message.

IM 12D7B2-E-H

42

Matrix example actual example actual example actual example actual example action

CODE 14 TEMPERATURE T1 ... T5 O 25 50 75 100

CODE 15 SOLUTION 1 L1 31 53 76 98 119

CODE 16 SOLUTION 2 L2 86 145 207 264 318

CODE 17 SOLUTION 3 L3 146 256 368 473 575

CODE 18 SOLUTION 4 L4 195 359 528 692 847

CODE 19 SOLUTION 5 L5 215 412 647 897 1134

Temp. 0 ppb 4 ppb 10 ppb 20 ppb 100 ppb

Cation 1 0 0,00975 0,152 0,31 0,62 1,23
Conductivity 25 0,0559 0,25 0,50 1 2
µS/cm 50 0,1752 0,385 0,70 1,35 2,70

75 0,4092 0,62 0,96 1,7 3,3
100 0,7681 0,98 1,3 2,1 3,9

Ammonia 2 0 0,00975 0,122 0,23 0,43 0,82
Conductivity 25 0,0559 0,25 0,50 1,0 2,0
µS/cm 50 0,1752 0,41 0,80 1,62 3,35

75 0,4092 0,65 1,13 2,3 4,8
100 0,7681 1 1,52 2,9 5,9

Morpholine 3 0 0,00975 0,149 0,30 0,59 1,15
Conductivity 25 0,0559 0,25 0,50 1 2
µS/cm 50 0,1752 0,375 0,70 1,38 2,8

75 0,4092 0,60 0,97 1,8 3,55
100 0,7681 0,98 1,38 2,35 4,5

1% 2% 3% 4% 5%

Hydrochloric 4 0 65 125 179 229 273
Acid 15 91 173 248 317 379
mS/cm 30 114 217 313 401 477
1-5% 45 135 260 370 474 565

60 159 301 430 549 666

Nitric Acid 5 0 39,5 76,1 113,4 147,2 179,5
mS/cm 20 57,4 108,5 161,4 210 258
1-5% 40 81,4 148,1 215 275 330

60 99,9 180,8 260 331 397
80 127,8 217 299 374 448

10-7 Matrix examples

IM 12D7B2-E-H

Printed in The Netherlands, 04-603 (A) Q

IM 12D7B2-E-H

Subject to change without notice
Copyright

©

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