yokogawa manual instruction · instruction manual model ph200 2-wire ph transmitter ... additional...

IM 12B6C2-E-H6th edition

Instruction Manual

Model PH2002-wire pH transmitter

YOKOGAWA

FAILHOLD

MEASUREAUT.CALMAN.CALDISPLAYTEMP.

YES NO

ENT

OUTPUTSET HOLDSERVICE

*NO MODEYES

> ENT>

MODETEMP.MAN

HOLD

pH

mV

FAILHOLD

MEASUREAUT.CALMAN.CALDISPLAYTEMP.

YES NO

ENT


*NO MODEYES

> ENT>

MODETEMP.MAN

HOLD

pH

mV

OUTPUT HOLDFLAG

MEASUREDVALUE DISPLAY

MESSAGE DISPLAY

KEY PROMPT FLAGS

SELECTION KEYSYES : Accept settingNO : Change to new setting

ADJUSTMENT KEYS> : Choose digit for adjustment^ : Adjust digit (to decrease pass

through zero)ENT : Enter new value

NOTE: The first digit changes from 1, -1, - to blank

SELECT MODE MEASURE/MAINTENANCE

Can be used to escape program at anytime

MANUAL TEMPERATURECOMPENSATION FLAG

FAIL FLAG MENU POINTER FLAGS

MENU FOR MAINTE-NANCE FUNCTIONS(see chapter 5)

MENU FOR COMMIS-SIONING FUNCTIONS(see chapter 4)

SELECT MODEMEASURE/COMMISSIONING

IM 12B6C2-E-H

IM 12B6C2-H-H

CONTENTS

1. INTRODUCTION ..................................................................11-1. Application......................................................................11-2. Required components for pH measurement ...................11-3. Identification ...................................................................1

2. TECHNICAL SPECIFICATIONS...........................................22-1. General specifications.....................................................22-2. Functional description.....................................................3

3. INSTALLATION AND WIRING .............................................43-1. Installation and dimensions.............................................4

3-1-1. Installation site ...................................................43-1-2. Mounting methods.............................................4

3-2. Wiring of sensors............................................................63-2-1. General precautions...........................................63-2-2. Additional precautions for installations in

hazardous areas ................................................63-2-3. Liquid earth........................................................63-2-4. Access to terminal and cable entry ....................63-2-5. Connection diagram for sensors ........................7

3-3. Wiring of power supply ...................................................83-3-1. General precautions...........................................83-3-2. Additional precautions for installations in

hazardous areas ................................................83-3-3. Connection of the power supply ........................83-3-4. Switching the instrument on...............................8

4. COMMISSIONING..............................................................114-1. Operations overview .....................................................114-2. Output range adjustment.....................OUTPUT...........124-3. Set up the HOLD function ...................SET HOLD........144-4. Sensor selection and diagnostics..................................16

4-4-1. Selection of measurement and reference electrode..........................................................16

4-4-2. Selecting a temperature sensor .......................164-4-3. Off-line calibration checks ................................164-4-4. On-line impedance chacks ..............................16

5. MAINTENANCE..................................................................175-1. Automatic calibration...........................AUT.CAL...........185-2. Manual calibration ...............................MAN.CAL .........205-3. Selecting a value to display .................DISPLAY...........225-4. Temperature compensation .................TEMP ...............245-5. Hold output function .....................................................26

6. TROUBLE SHOOTING.......................................................286-1. Introduction ..................................................................286-2. Error messages and explanation...................................29

IM 12B6C2-E-H

7. SERVICE MODE.................................................................307-1. Introduction .................................................................307-2. Access to service settings ...........................................317-3. Temperature function...................................................327-4. Temperature sensors ...................................................327-5. Sensor checking..........................................................337-6. Display resolution ........................................................347-7. Signalling of fail condition ............................................347-8. Stabilization check.......................................................347-9. Auto return ..................................................................357-10. Buffer tables ................................................................357-11. Temperature adjustment..............................................367-12. Manual adjustment of ITP, slope and

asymmetry potential....................................................367-13. Passwordprotection by three digit code......................377-14. Restore default settings ..............................................37

8. CLASSIFICATION...............................................................388-1. Cenelec ........................................................................388-2. FM................................................................................39

9. CHANGE FROM PH TO ORP MEASUREMENT ..............409-1. How to change from pH measurement to

ORP measurement .......................................................409-2. Commissioning the transmitter .....................................409-3. Maintenance of the transmitter .....................................409-4. Special features ............................................................409-5. Wiring diagram .............................................................419-6. Buffer values.................................................................41

APPENDIX A............................................................................42

IM 12B6C2-E-H

1-1. ApplicationThe EXA PH200 transmitter is a 2-wire pHinstrument intended to be used in industrialinstallations in the field. For easy maintenan-ce and operation it should be located closeto the sensors. It is powered from a remotelow voltage DC power supply through the 2-wire connection. The EXA PH200 is compa-tible with most commercial available pH sen-sors 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 thenbe installed in Zone 1 with the sensors inZone 1 or Zone 0.

The micro-processor is used in this instru-ment for continuous sensor diagnostics,flexible on site commissioning and fine tu-ning by advanced functions.

In general a pH loop can be set up for diffe-rent purposes:- To be part of a total process control sys-

tem- To indicate dangerous limits of a process.- To monitor product quality.

1-2. Required components for pH measurement

1. A pH electrode and a reference electrodeor a combined pH-reference electrode.

2. A temperature sensor Pt100 (accordingto IEC 751 or DIN) or Pt1000

3. A fitting for the above electrodes withaccessories

4. Signal cables with or without extensionboxes, etc.

5. The EXA PH200 2-wire transmitter withmounting accessories for wall or pipemounting

6. A DC power supply (nominal 24 V DC)with cabling and optional zener barriersor an intrinsic safe power supply

7. Peripherals: e.g. strip-chart recorder,panel indicator, PID-controller.

1-3. IdentificationThe instrument has an identification label,which is fixed to the front plate. This serves as a reference for the full modelcode, power supply voltage and serial num-ber. This label also carries authorised marksto certify compliance with the current regula-tory norms.

1

1. INTRODUCTION

MODEL

SERIAL NO.

SUPPLY

2-1. General specificationsA. Intrinsic safety

– BASEEFA : Certified by and meets the require-ments of EEx [ia] ib IIC T4 of CENE-LEC Certificate nr. : 89C2379)

– FM : For IS CL1, DIV1, GP ABCDT3B for TA-30 to 70 °CT4 for TA-30 to 40 °CApproval report: J.I. 1Y1A7.AX

– CSA : For Ex[ia] Class 1, Div. 1, Groups Cand D, T4AApproval file: LR 102851-1

B. Indicating range :-1 to +15 pH.

C. Transmission signal : 4 - 20 mA DC; max. load 550 Ω

D. Transmission range : 0 - 14 pH.User programmable to any rangewith a minimum span of 1 unit.

E. Power supply– Model PH200G : 17 - 40 V DC,

dependent on load– Model PH200S : 17 - 31,5 V DC,

dependent on loadF. Climatic conditions

– Ambient temperature : -10 to +55 °C– Storage temperature : -30 to +70 °C– Relative humidity : 10 to 90%– Weather protection : Rain and dust-tight IP65 (NEMA 4X)

G. Housing– Material : Cast aluminium with chemical resi-

stant coating– Window : Flexible poly-carbonate– Colours : Moss green/off-white– Cable glands : Polyamide– Cable entries : Two h” glands

Hose connection optional– Earth connection : For external ground

H. Mounting possibilities– Surface mounting : Two M6 bolts, 9 mm length– Wall/Pipe mounting : With optional mounting kit– Sunlight protection : With optional hood– Panel mounting : 154 x 172 octagonal with

30 mm corners (fixing with self-tap-ping screws

I. Shipping details– Dimensions : 162 x 178 x 115 mm– Package : 225 x 225 x 220 mm– Weight : ca. 2,5 kg

J. Safety and security– Data protection : EEPROM memory– Interference test : According IEC 801– Power down : No affect, reset to measurement

2. TECHNICAL SPECIFICATIONS

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2

IM 12B6C2-E-H

2-2. Functional descriptionThe EXA PH200 is a real time micro-control-ler operated pH analysing system. It uses adedicated micro-controller with exclusivelydeveloped software to control all functionsnecessary in such a system. The input andoutput functions are concentrated in theanalogue section of the instrument. Eventhese functions are operated through specialinterfaces designed to give a minimum ofinterference problems to the digital func-tions. The digital and logic functions aredesigned to operate securely. The uniqueFAIL-function can give a warning when themicro-controller has found a fault in themeasuring loop. This is accomplished bysending a discrete 22 mA signal on the out-put. The micro-controller checks the workingof the analogue to digital input converter cir-cuit and watches over the conversion to theoutput signals. By using non-volatile memory(EEPROM) for the essential in formation theoperating parameters are fixed in memorywithout the need for a battery. The softwareis designed with the user in mind. It uses asimple step by step, question and answerstyle to communicate with the operator bygiving messages on the second line of thedisplay and indicating which keys are to bepressed in the display too.

The user-interface is limited to a basic set of6 keys accessible through the flexible win-dow cover. The keys are scanned conti-nuously and actions are taken immediately.An extensive system of checking va lues andparameters is implemented in the software .The 2-wire design gives maximum flexibilityof operation with other industrial instrumentsand controlling systems. An intrinsically safeversion is available for hazardous areas. Therugged housing is designed for outdoor use(IP65). In addition it is shaped in a way thatindoor panel mounting is also possible. Theoptional universal mounting kit includesbrackets for all mounting methods. Thecommissioning of the instrument can beperformed on site or in advance. A threelevel operating system keeps the approachclear and distinguishes between every dayoperation and maintenance against one timeoperations like commissioning or fine-tuning.All this makes the EXA PH200 operate like anormal analogue transmitter with a numberof additional functions.

These extra functions are only possible byusing a micro-controller at the heart of thesystem:• Sensor checking durig measurement (1)• Simplified calibration through a semi-

automatic sequence.• Additional process temperature compen-

sation can be activated.• Simple range adaptation making it a ver-

satile instrument.• Wide selection of temperature sensors.• A HOLD-function for the output.• Three buffer tables can be programmed.• Programmable isothermal point of inter-

section.• Protection against unauthorized access

by a passcode.

(1) European patent No. 0241601US patent No. 4777444

3

3. INSTALLATION AND WIRING

IM 12B6C2-E-H

3-1. Installation and dimensions

3-1-1. Installation siteAs the transmitter is a rain-tight type it canbe installed outdoors as well as indoors. Itshould, however, be installed as close aspossible to the sensors avoiding long cablelengths 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 humidityshould be within the limits of the specifica-tions .

3-1-2. Mounting methodsThe EXA PH200 transmitter has universalmounting 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 hori-

zontal or vertical pipe (maximum diame-ter 50 mm).

4

Panel mounting Surface mounting

DimensionsCut-outs for panel mounting

2 x M6 (Screws)

Unit: mm (“)Unit: mm (“)

154 (6.06`)162 (6.4)

180

(7)

77

115 (4.5)

30 1

.2)

30 (1.18)

172(

6.77

)2x ø4

min. 203 (8)m

in.

229

(9)

IM 12B6C2-E-H

5

Option /M: Universal wall/pipe mounting kit

Pipe mounting (vertical)

Pipe mounting (horizontal)

2” Pipe 2” Pipe

Wall mounting

115(4.53)70 (2.75)

56 (2.2)

200

(7.8

7)

2x ø6.6(0.26)

4x ø10(0.4)

77 (3.03)

IM 12B6C2-E-H

3-2. Wiring of sensors

3-2-1. General precautionsGenerally, transmission of signals from pHsensors is at a very low voltage and highimpedance level. Thus a lot of care must betaken to avoid interference. Before connec-ting sensor cables to the transmitter makesure that next conditions are met: – the sensor cables are not mounted in

tracks together with high voltage and orpower switching cables

– only standard coaxial electrode cables orextension cable are used

– the transmitter is mounted within the dis-tance of the sensor cables (max. 10 m)

– the setup is kept flexible for easy inser-tion and retraction of the sensors in thefitting.

3-2-2. Additional precautions for instal-lations in hazardous areas

Make sure that the total of capacitances andinductances connected to the input termi-nals of the EXA PH200 do not exceed thelimits given in the certificate.This sets a limit to the cable and extensionsused. – Grounding:• If the sensors are mounted in a grounded

fitting, the external earth connection onthe left hand side of the transmitter mustbe connected to "protective" earth.

• If the sensors are mounted in a fitting iso-lated to ground, it is recommended (notrequired) to connect the earth connectionon the left hand side of the transmitter to"protective" earth.

– The intrinsic safe version of the EXAPH200 instrument can be erected inZone 1.

– The sensors can be installed in Zone 0 orZone 1 if a safety barrier according to thelimits given in the system certificate isused.

3-2-3. Liquid earthIn all circumstances, the sensor side of themeasuring loop must be grounded to themeasuring liquid. The EXA PH200 usesadvanced differential high impedance inputcircuits. This technique calls for a groundingto the liquid. In addition to that the sensorchecking circuits also use the liquid earth formeasurement of impedance of the sensors.All Yokogawa fittings have provisions for thisconnection. It is usually called liquid earth inall our manuals. A separate connection should be made tothe terminal numbered 14 in all cases to geta proper and stable measuring loop.

3-2-4. Access to terminal and cableentry

1. To access terminals remove the frontcover of the EXA PH200 by releasing the4 captive screws.

2. Thread the sensor cables into the con-nection space and connect the cables tothe terminals as indicated in the wiringdiagram. Make sure all connections arefirm and do not touch each other.

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

4. The optional hose connection is used toguide the cables coming from an immer-sion fitting through a protective plastictubing to the transmitter.

6

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3-2-5. Connection diagram for sensors

+ - G 11 12 14 13 17 15 16

Rd Bl Rd Bl Rd Bl

+ - G 11 12 14 13 17 15 16

Rd Bl Wt RdBl

+ - G 11 12 14 13 17 15 16 + - G 11 12 14 13 17 15 16

T1 T2 SE RE GE S

Rd=Red, Bl=Blue, Wt=White,

Single electrodes

Temperature CombinedLiquid earth

Temperature - Reference pHPt 100 AgCl glass(Pt 1000) (other) (other)

EXA compact and retractable electrodes pH∑ Combined electrode

Combined electrodes

Liquid earth

Connect the numbered cable leads to thecorresponding terminals

IM 12B6C2-E-H

3-3. Wiring of power supply

3-3-1. General precautionsDo not activate the power supply yet. Firstmake sure that the DC-power supply isaccording to the specifications given.

WARNING: DO NOT USE ALTERNATINGCURRENT OR MAINS POWER SUPPLY! !

The cable leading to the distributor (powersupply) or safety barrier transports power toand output signal from the transmitter. Use atwo conductor shielded cable with a size ofat least l.25 mm2 and an outside diameter of9 to 15 mm. The cable gland supplied withthe instrument accepts these diameters. Themaximum length of the cable is 2000 metre.This ensures the minimum operating voltagefor the instrument.

3-3-2. Additional precautions for instal-lation in hazardous areas

1. Ensure that the total of capacitances andinductances connected to the terminalsof the EXA PH200 do not exceed thelimits given in the certificate of the safetybarrier or distributor.

2. The cable used should preferably have aBLUE colour or marking on the outside.

3. Grounding:• If the transmitter is mounted on a

grounded surface (e.g. a metal framefixed in the soil) the shield of the 2-wirecable may NOT be connected toground at the distributor.

• If the transmitter is mounted on a non-conducting surface (e.g. a brick wall) itis recommended to ground the shieldof the 2-wire cable at the distributorend.

4. Installation for EEx ia (sensors in Zone 0or 1):Generally, the distributor with input/out-put isolation has no external earth con-nection. If there is an earth connection onthe distributor and the external connec-tion of the transmitter is connected to"protective" earth, the shield of the 2-wirecable may NOT be connected to "protec-tive" earth at the distributor too.

3-3-3. Connection of the power supplyThe terminal strip is accessed as wasdescribed in § 3-2-4. Use the left-handgland to insert the 2-wire cable to the trans-mitter. Connect the supply to the terminalsmar ked +, - and G as is indicated in thefigures on pages 9 & 10.

3-3-4. Switching the instrument onAfter all connections are made and checked,the power can be switched on from the dis-tributor. Observe the correct activation of theinstrument at the display. If for any reasonthe display does not indicate a value, con-sult the trouble shooting section.

8

IM 12B6C2-E-H

Dependance of load to supply voltage

9

Wiring diagrams for power supply

General purpose designpH-transmitterEXA PH200G

Sen

sor

Distributor

Out

put

Sup

ply

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

1200

1000

800

600

400

200

0 1718 20 24 40

Ohm

550

Supply voltage (V)

Load

res

ista

nce

(Ω)

+

–

+

–

G

Wiring diagrams for hazardous areas

IM 12B6C2-E-H

10

Intrinsically safe design(CELENEC standard EEX ib [ia] IIC T4)pH-transmitterEXA PH200S

Intrinsically safe design(CELENEC standard EEX ib [ia] IIC T4)pH-transmitterEXA PH200S

EEx ibCertified safety barrier

EEx ibCertified distributor withinput/output isolation

Electronic currentlimiting barrierVmax: 31.5 Vlmax: 35 mAPmax: 1,1 WZenerbarrier withresistorVmax: 28 Vlmax: 93.3 mAPmax: 0.66 W

Shunt zener barrier orsupply unit orisolated repeaterVmax: 22 VImax: 85 mA

Sen

sor

Distributor

Out

put

Supply

Sen

sor

Out

put

Sup

ply

Protective earthProtective earth

Protective earth

Hazardous area Safe area

Zone 0 or 1 Zone 1

Hazardous area Safe area

Zone 0 or 1 Zone 1

+

–

+

–

G

+

–

+

–

G

IM 12B6C2-E-H

4-1. Operations overview

NOTE: All 3 levels can be separately protected by a password (see §7-13).

11

4. COMMISSIONING

Routine Use Chapter

MAINTENANCE AUT.CAL Calibration with buffer solutions 5-1

Operation by keys through MAN.CAL Calibration in process 5-2

closed cover DISPLAY Show or fix additional values 5-3

TEMP Select automatic or manual

temperature compensation 5-4

HOLD Switch HOLD-function on/off 5-5

COMMISSIONING OUTPUT Adjusting the output function 4-2

Operation by *-key when SET HOLD Activating the HOLD-function 4-3

cover is removed

SERVICE SERVICE Finetuning the performance 7

Operation by coded entry

from commissioning

1. Access output

Remove cover by releasing 4 screws.

Access to commissioning menu

Select output function

Select OUTP

Confirm selection

2. Adjust low span value

Display will show *4 mA

Adjust value for low span

Select digit to adjust

Adjust digit

Confirm adjusted value

3. Adjust high span value

Display will show *20 mA

Adjust value for high span


Adjust digit


Return to measurement

4-2. Output range adjustment

YES

ENT

>

^

ENT

MODE

>

^

NO

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12

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.

x

MODE


YES NO

YES NO

MODE *


YES NO MODE

ENT


YES NO MODE

ENT

pH

IM 12B6C2-E-H

1. What is the Output-range?The display will always show the actual valuebetween -1 and 15 pH.

The output range is a linear function of mAversus pH and is fixed by two points. As the output is fixed to 4..20 mA the twopoints of the linear function have to be pro-grammed to set the range.

The factory setting is a full range of 0..14pH.Any value between -1.. + 15 pH is accepta-ble for both points. A minimum span of 1unit must be kept. An error E19 will point to not acceptablevalues.

NOTE: 1. The linear output signal is limited to 3.9 to

20.5 mA giving a safety area of 2.5% atboth ends.

2. Values below 3.9 or above 20.5 mA arenot related to input values and signal amalfunction.

2. How to adjust?EXAMPLE:The EXA PH200 has to be programmed fora range of 2 ... 12 pH.

Adjust 4 mA to 2.00 pHAdjust 20 mA to 12.00 pH

The instrument will now correct its calcula-tion for the output signal accordingly.

3. Calculation exampleThe current to be set at the output is calcu-lated as follows:

pH - pHmin

mA = x 16 + 4pHmax - pHmin

pH = actual valuepHmin = value at 4 mA

pHmax = value at 20 mA

pHmax - pHmin = span (≥ 1 pH)

It is advisable to choose a span devisable by10, 5 or 2 for easy reading on scales.

4. Other possibilitiesSet a 22 mA signal on the output, whenFAIL is on (see §7-7).

13

4-2. Output range adjustment

4-3. Set up the HOLD-function

IM 12B6C2-E-H

1. Access to HOLD-function

Remove cover by releasing 4 screws.

Push this key to selectCommissioning mode

Select HOLD

Move pointer to SET HOLD

HOLD = HOLD-function

Confirm selection

2. Activate HOLD-function

Display shows actual status*H.OFF = HOLD not active*H.ON = HOLD activated

Activate (deactivate) HOLD

Changing setting

Confirm setting

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

Select HOLD fixed or lastChange selection

Confirm selection

3. Select value to hold

Display shows current setting

Adjust fixed value


Adjust value of digit

Confirm setting


14


YES NO

YES NO

MODE *

.OUTPUTSET HOLDSERVICE

YES NO MODE

ENT.

YES

ENT

>

^NO

YES

NO

YES

NO

x



MODE

MODE


YES NO

YES NO

MODE *

IM 12B6C2-E-H

1. What is HOLD?HOLD is a function freezing the output signaltemporary, during normal maintenance, pre-venting all sorts of alarming situations tooccur. Two possibilities are generally used:a. Keeping the output at the LAST value

just before the start of maintenance. Thisshould be used when recording and notcontrolling instruments are connected tothe output signal.

b. Keep the output at a preset FIXED valuewhich will not cause any of the alarms togo off or any controlling action to betaken. This is the preferred situationwhen dealing with pH-control systems.

2. How does it work?The HOLD-function has to be activated fromthe commissioning menu before it can beused. The EXA PH200 will keep the output frozenduring the following events: a. Access to the commissioning menu. b. Access to either of the calibration modes. c. Switching it from the maintenance menu.

HOLD is signalled in the display by a specialflag.

The operator is prompted to switch HOLDon or off before returning to nor mal mea-surement.

3. ExampleIn a neutralization set-up with both acid andbase dosing systems the neutral value is pH7.00.

Activate the HOLD function and choose theFlXed output value.

The span was set for 2-12 pH (see §4-2).

Thus pH 7.00 = 12 mA. Adjust the presetvalue for the output at 12 mA.

During maintenance the output will be at 12mA = pH 7.00 and no acid or base will bepumped.

4. Auto returnHold can be de-activated after 10 minutes ifno key is pressed. To cancel this function(see §7-9).

15

4-3. Set up the HOLD-function

IM 12B6C2-E-H

4-4. Sensor selection and diagnosticsThe inputs of the EXA PH200 transmitter arefree programmable for ease of retrofit onexisting installation. Standard glass pH-elec-trodes, Ag/AgCI reference electrodes andPt100 sensor need no programming. If thereis a mismatch of the sensors connected afault will be indicated with a signal field onthe display and if activated by a 22 mA signal.

4-4-1. Selection of measurement andreference electrode

The EXA PH200 is preprogramed to ac-ceptindustry standard glass electrodes and refe-rence electrodes. Checks for asymmetry-potential and slope are implemented duringcalibration. The on-line impedance check onboth sensors is not initialized unless activa-ted from the service level §7-5. The EXA issuitable for all type of electrodes (e.g.Enamel, Antimony). In §7-3 the specificIsothermal point of intersection (ITP), slope(pH/mV) and asymmetry potential can be setfor each type of electrode.

4-4-2. Selecting a temperature sensorThe EXA PH200 has been factory set for aPt100 temperature sensor to DIN standards.This will give satisfactory results when thenormal electrode cable length is used. Tocorrect for cable resistance it is possible tocalibrate the sensor from the service level(zie §7-11).The highest accuracy is obtained by using aPt1000 element with the EXA PH200 trans-mitter. This element gives a ten-fold increasein resistance dependance over a Pt100 sen-sor. Setting the instrument for Pt1000 isfrom the service level at §7-4.

4-4-3. Off-line calibration checksThe EXA PH200 transmitter incorporates achecking of the asymmetry-potential after acalibration has been performed. This is validfor both manual or automatic calibration.The actual value can be called up from thedisplay routine in the maintenance menu(AS). A large value can indicate a poisoningof the reference system used. If the asym-metry-potential exceeds + 120 mV or -120 mV an error E2 will be generated. To disable this checking see §7-5.The EXA PH200 also checks for the slope ofthe pH sensor after automatic calibrationhas been performed. The actual value of theslope can be called up from the display rou-tine in the maintenance menu (SL). Thevalue is an indication for the "ageing" of thesensor. If the value stays within the limits of70 to 110 % of the theoretical value of 59.16 mV/pH at 25°C it is accepted.Otherwise an error E3 is generated. Disablethis testing from the service level §7-5.

16

IM 12B6C2-E-H

4-4-4. On-line impedance checksThe EXA PH200 transmitter is delivered fromthe factory with an impedance check disab-led. To activate this impedance checkingrefer to §7-5. The impedance check workson both measuring and reference electrode,but not in the same way. The measuringelectrode is checked for presence of a highimpedance on the input side. An open cir-cuit is signalled by an error E5. A short cir-cuit is signalled by an error E4. The impe-dance of the reference electrode is meas-ured (RZ). The actual value (in kilo Ohm) canbe called up from the display routine in themaintenance menu. When pH is measuredin high purity water it is necessary to adjustthe reference impedance for the low con-ductivity of the solution. In general a highimpedance value can be related to a dia-phragm clogging, fouling or non-immersionof the sensors. If the value exceeds the limitset an error E6 is generated. Activation andlimit setting (*IM.LMT) is done from the servi-ce level §7-5.

17

1.Access automatic calibration

AUT.CAL = Automatic calibration

Access to maintenance mode

Select automatic calibration

Move pointer to AUT.CAL

Confirm selection

2. First buffer calibration

CAL 7 = Calibrate at pH 7Select pH value for first buffer solution

Accept displayed buffer

Select other value

Calibration can be ended *Continue calibration with secondbuffer solutionEnd calibration with on buffer only(asymmetry potential only)

3. Second buffer calibration

CAL 4 = Calibrate at pH 4.Select pH value for second buffer solution

Accept displayed buffer

Select other value

Calibration can be ended *End calibrationRepeat calibration with first buffersolution

5. MAINTENANCE5-1. Automatic calibration

IM 12B6C2-E-H

18

MEASUREAUT.CALMAN.CALDISPLAYTEMP.HOLD

YES NO

YES NO

pH

MODE


YES NO

YES NO

MODE


YES NO

YES NO

MODE



MODE

MODE

NO

YES

NO

YES

NO

YES

NO

YES

NO

YES

Insert electrodes in buffer solution. Display shows CAL andflashes while instrument searches for stable measurement.Display show CAL.END. Measurement is now stable.

*) The value shown on the display can deviate from the buffer value. This is fixed after calib-ration is completed.

Insert electrodes in buffer solution. Display shows CAL andflashes while instrument searches for stable measurement.Display show CAL.END. Measurement is now stable.

IM 12B6C2-E-H

1. What is automatic calibration?Automatic calibration is the usual process ofcalibrating a pH measuring loop with the aidof two buffer solutions.

The first calibration is usually at pH 7; this isto correct the asymmetry potential of sen-sors (zero). The second calibration is most commonlymade at pH 4. This corrects the slope of thesensors (sensitivity) . After this two point cali-bration the instrument is accurate to thebuffers used. The EXA PH200 gives you the freedom touse up to three buffer-solutions you want inany sequence you like. The buffer solutionscan be programed in memory tables. In the automatic calibration mode the instru-ment prompts the operator for the re quiredbuffer solution, checks the signal for stableconditions and then calibrates. The new cali-bration is then checked and a warning isgiven if values are unacceptable.

During calibration the output will be frozen ifHOLD was activated.

2. How does it work?A. The instrument asks for a buffer. Accept

or changeB. The sensor is immersed and checked for

stabilityC. CAL.END, Stop or move on the second

calibrationD. Values acceptable or rejected.E. After second calibration give YES to end

session.

NOTES:1. It is not necessary to have the calibration

points within the measuring range of theinstrument, it is however advisable to doso.

2. If no keys are pressed for 10 minutesand the calibration was not finished theinstrument will return to measurementwith the old calibration values.

3. If HOLD was activated the instrument willreturn to measurement after another 10minutes.

Press YES to start the calibration. After sta-bilization CAL.END will show. Press NO tomove on to pH 4.

3. ExampleStandard calibration procedure. Select AUT.CAL routine using MODE andYES keys (enter pass code if necessary).Select buffer pH 7using YES key.

Insert the rinsed sensors from the processinto a solution of pH 7.00 at 25°C. CAL.END display on stable reading. PressYES to end or NO to go on to next buffer.

Clean the sensor with water and insert intobuffer solution of pH 4.00 at 25°C. CAL.END display on stable reading. PressYES to end.

The whole process will not take more than15 minutes and should be repeated at leastonce every 2 months or whenever the EXAPH200 signals a malfunction with anERROR-message .

4. Further possibilities- Other buffer solutions than after 4, 7, 9. - Using Special buffer tables for temperature

compensation (e.g. calibration in warmbuffers) §7-10.

19

5-1. Automatic calibration

5-2. Manual calibration

IM 12B6C2-E-H

1. Access to manual calibration

MAN.CAL = Manual calibration


Select manual calibration

Move pointer to MAN.CAL

Confirm selection

2. Adjust value manually

Display shows measured valueSTART = Start manual calibration

Confirm start of adjustment (dis-play frozen, ready for adjustmentto new value)

Adjust new value. Adjust process value to previously determi-ned value (e.g. from hand-held pH-meter)


Adjust value


3. End calibration

CAL.END = End of calibration

End calibrationEnd calibration and return tomeasurementContinue routine to calibratesecond point when using buffersolution (repeat step 2)

Error E02 or E19 indicate manual calibrationis not acceptable

20


YES NO

YES NO

MODE

M E A S U R EA U T. C A LM A N . C A LD I S P L AYT E M P.H O L D

YES NO

YES NO

MODE

.


YES NO

YES NO

MODE



MODE

MODE

NO

YES

YES

ENT

>

^

YES

NO

IM 12B6C2-E-H

1. What is manual calibration?Manual calibration or process calibration isthe calibration executed with a freshly takensample from the process.

This sample is then measured with an offline instrument and the value obtained isprogrammed into the EXA PH200 transmit-ter. Manual calibration can be used for calibra-ting the sensors with a buffer solution spe-cially made for this purpose.

NOTE: This routine can also be used to calibratewith two points as an alternative to automa-tic calibration e.g. for occasional use of notprogramed buffers.

2. How does it work?1. Take a sample from the process.

2. Measure the pH with an off-line pH meterwhich has been previously calibrated withstandard buffers and is equiped with anautomatic temperature compensation.

3. Adjust the value of the in-line EXA PH200transmitter to the measured value.

4. Any values outside the normal operatingrange of the instrument are signal led byError 19.

3. ExampleThe EXA PH200 indicates a process value ofpH 6.54 at 50°C.

A freshly calibrated portable pH-meter inser-ted into a hot sample reads 6.62 pH at50°C.

The value is adjusted to the process value atmanual calibration to bring the values inagreement.

A laboratory check of the same sampleshows the value to be pH 6.612 at 25°C.

The difference is due to the change of pH ofthis particular sample with temperature.

21

5-2. Manual calibration

1. Access display routine

DISP = Display routine


Select display

Move pointer to DISPLAY

Confirm selection

2. Read data

The second line of the display will show thepossibilities

Parameter UnitTemperature °COutput signal mAPotential mV

AS Asymmetry mVSL Slope %RZ Impedance Ref. electrode kΩREL Software release

3. Reprogram data display

Move to desired value for diaplay

Confirm selection


IM 12B6C2-E-H

22

5-3. Selecting a value to display


YES NO

YES NO

MODE


YES NO

YES NO

MODE


YES NO

YES NO

MODE

MODE

NO

YES

NO

YES



MODE

MODE

IM 12B6C2-E-H

1. What is the display routine?The second line in the display is intended tobe used to:– show actual status– show messages– show errors

When delivered from the factory the EXAPH200 shows the temperature on thesecond line.

You can make the instrument show a diffe-rent parameter on the second line by selec-ting it from the list at the right.

2. What can you read?Temperature actual valueOutput signal actual valuePotential actual valueAsymmetry measured valueSlope measured valueImpedance actual value

Reference impedance is an actual value.

The choice of temperature units is donefrom the Service level.

Reference impendance is shown to indicatethe status of the diaphragm of the referenceelectrode. Glass electrode impedance is alsochecked but not shown.

The release version is an indication for theservicing of the instrument and cannot befixed in the display.

3. ExampleTo check the value of the output signal(4...20 mA) it is displayed on the secondline.

Measuring range 2 - 12 pHOuptut signal 4 - 20 mA

Process value 8.5 pHOutput value 4.4 mA

When the second line is changed to displayoutput the current signal is visible all thetime.

Whenever HOLD is activated the value onthe display is frozen to the programmedvalue (using the FIXED setting).

Pressing MODE will take you back tomeasuring and the temperature will showagain.

4. Further possibilities0.01 pH/0.1 pH display resolution. (See §7-6).

23

5-3. Selecting a value to display

5-4. Temperature compensation

IM 12B6C2-E-H

1. Access temperature compensation

TEMP = Temperature compensation


Select temperature compensation

Move pointer to TEMP

Confirm selection

2. Select automatic or manual temperatu-re compensation

T.AUTO = Automatic temperature compen-sation

T.MAN = Manual temperature compensa-tion

Select automatic/manual compensationChange displayed selection

Confirm selection

Adjustment of temperatureOnly when manual is selected


Adjust value


3. Setting the temperature coefficient *

COEFF = Temperature coefficient pH change per 10°C

When the additional process compensationhas been commissioned from the servicelevel this menu will show.

Adjust solution temperature compensationSelect digit to adjust

Adjust value


* (only when process compensation wasactivated in §7-3)

24


YES NO

YES NO

MODE


YES NO MODE

ENT


YES NO

YES NO

MODE

MODE

NO

YES

NO

YES

ENT

>

^

ENT

>

^



MODE

IM 12B6C2-E-H

1. What is compensated for?Temperature influences the sensitivity of theglass electrode.

To nullify this effect the EXA PH200 has tocompensate the pH value with the formuladerived by Nernst.

To be able to do this the temperature has tobe measured as well. Either by a seperatesensor or a temperature setting.

Temperature compensation can be set tomanual if the process is near pH 7 or atfixed temperature.

2. How is it compensated?The process temperature is measured with aseparate circuit connected to the temperatu-re sensor (e.g. Pt1000 resis tor).

The resistance value of the temperature sen-sor is calculated into the temperature value.

This value is used to calculate the compen-sated value for the pH on the display.

3. ExampleSetting the manual temperature compensation to a fixed setting of 30°C.

Press NO to change from default automaticcompensation to manual compensation.

The display will show TEMP °C and thevalue can be adjusted to 30°C. Press ENTto confirm the setting.

The display will show TEMP.MAN at the topto indicate your choice.

4. Further Options- Process temperature compensation (see

Service settings §7-3). - Calibrating the temperature circuit (see

Service settings § 7-11).

25

5-4. Temperature compensation

5-5. Hold output function

IM 12B6C2-E-H

1. Access HOLD

NOTE:This function can only be used if activatedduring commissioning (see §4-3).


Select HOLD functionMove pointer to HOLD

Select HOLD

2. Switch HOLD on/off

Display will blink HOLD and YES/NO

Switch off HOLD function

Switch on HOLD function

HOLD in left top of display is switched

26


YES NO

YES NO

MODE


YES NO

YES NO

MODE



MODE

MODE

NO

YES

NO

YES

IM 12B6C2-E-H

1. What is HOLD?Hold is a function which freezes the outputsignal temporarily, it is normally used duringmaintenance when the sensor is removedfrom the measured solution to preventunwanted controller reaction.

The HOLD function must be commissionedfrom the programming menu before it canbe switched on or off. See setup the holdfunction for more details (§4-3).

2. How does it work?From this level the HOLD function can onlybe switched ON or OFF.

HOLD is switched on when you press YESand HOLD blinks. When you press NOHOLD is switched OFF.

A flag is kept in memory and an indication ismade in the upper left corner of the displayfield.

The HOLD function only influences the out-put signal, no other functions are influenced.

The operator is prompted to switch HOLDon or off after having performed a mainte-nance function.

3. ExampleDuring the transfer of cleaning liquid into abatch reactor with a pH-control systemdosing acid or alkali, the HOLD function isswitched ON to prevent the controlling in-struments from running wild.

After cleaning has ceased and the newbatch has been started HOLD is switchedOFF again and pH control resumes.

27

5-5. Hold output function

6. TROUBLE SHOOTING

IM 12B6C2-E-H

6-1. IntroductionAs the EXA PH200 is a micro-processoranalyzing instrument, it performs continuousself-checks to verify its correct working.

The error messages resulting from faults inthe working of the micro-processor systemare few. Incorrect programming by the usercan be fixed through programming with cor-rected values. See the limits given in therespective paragraphs.

In addition to that the EXA PH200 alsochecks the electrodes to establish whetherthese are still functioning within the limitsimplemented through the service settings.

The EXA PH200 checks the glass electrodeimpedance for a low value to know if ithasn't broken or cracked.

The reference system is prone to more dis-turbances than the glass electrode in gene-ral. The impedance is measured and com-pared to the programmed value in memory.A high impedance signals a pollution of thediaphragm.

Furthermore the sensors are checked atcalibration to see whether they still are reac-ting fast enough to changes in pH.

After calibration the calculated asymmetrypotential and slope are checked to see ifthese are still within the limits specified in thesoftware. The slow shift of the asymmetrypotential could signal a poisoning of thereference system by the process.

The decrease of slope indicates a deteriora-tion of the sensitivity of the glass electrodeor can show a coating building up at theelectrode.

The remedy for each fault is given veryshortly. Process conditions determine whataction can be taken to correct errors. As theactual situation may vary, it is not possiblefor us to give you a full solution for all cases.If you have any problems or questions plea-se consult your nearest Yokogawa sales orservice organisation for assistance.

There is a distinction made in the weight oferrors. All errors are signalled by the FAILarea in the display. Only errors due to faultsin the measuring circuits also result in theactivation of the FAIL function switching the22 mA signal §7-7. These are indicated byan asterisk (*) in the error list.

28

Code Error description Possible cause Suggested remedyE0 Temperature of the buffer liquids is Buffer liquid is too hot Cool buffer liquid

out of range of 0 to 50 °C Bufer liquid is too cold Warm buffer liquidE1 Measurement has not stabilized Electrodes are fouled Clean electrodes

during calibration Glass electrode too slow Use other type (faster)Wrong type of glass electrode Use other type

E2 Calculated asymmetry potential out Calibration at pH 7 incorrect Recalibrate at pH 7of range of -120 to +120 mV Check if buffer solution is fresh

E3 Calculated slope is out of range of Glass electrode has aged Replace glass electrode70 to 110 % theoretical value Bad isolation on input Dry or replace cable

E4* Impedance of glass electrode too low Glass electrode cracked or broken Replace glass electrodeE5* Impedance of glass electrode too high Glass electrode coated or fouled Clean or replace glass electrode

Open circuit on measurement Check connections and cablesE6* Impedance of reference electrode too high Reference electrode fouled or clogged Clean or replace glass electrode

Liquid earth disconnected Clean or replace glass electrodeSensors not fully immersed Check installation

E7* Measured temperature too high Process temperature too high Cool process or use sample loopi.e. above 130 °C Wrong temperature sensor used Correct setting (§7-4)

Temperature sensor damaged Check connections and sensorE8* Measured temperature too low Process temperature too low Warm process or use sample loop

i.e. below -10 °C Wrong temperature sensor used Correct setting (§7-4)Short circuit in temperature input Check connections and sensor

E9* Measured value is out of pH range Temperature element broken Replace temperature sensorof -1 to 15 pH Temperature sensor disconnected Set temperature to manual

E10* EEPROM write error Fault in electronics Try again, if not succesful call your nearestYokogawa office

E15 Cable resistance to temperature sensor Cable resistance too high Use Pt1000 for accurate resultsexceeds 5Ω Corroded contacts Clean contacts and tighten

E17 Output inside minimum span < 1pH Incorrect programming by user Correct programmingE19 Programmed values are not accepted Incorrect programming by user Correct programming of last functionE20 All programmed values are lost Fault in electronics Call nearest Yokogawa office

Severe interferenceWhen errors appear that are not mentionbed in this list, please consult the Yokogawa service organization. A maximum of 2 errors can beindicated at the same time. *See §6-1.

IM 12B6C2-E-H

29

6-2. Error messages and explanation

IM 12B6C2-E-H

30

7. SERVICE MODE

7-1. IntroductionGenerally speaking their is no necessity toadjust the settings of the service section. Allparameters are pre-programmed to values(so-called defaults) enabling you to startworking immediately.

The advanced functions available throughthis section are only needed in some specificapplications. This fine-tuning of the in stru-ment gives a superior performance overanalogue 2-wire instruments.

If a function has to be adjusted it is called upwith the code mentioned. Having selectedthe code then give you the possibility to eit-her activate or adjust the values for thisfunction. After this you will return to the entrypoint to make other adjustments or go backto the measuring status.

If errors are made during the programmingprocess, these will be indicated, no actionwill be taken and you can start the program-ming again

Code Routine Use Chapter

01 Temperature compensation Process comp. on/offand units Select °C or °F 7-3

02 Temperature sensors Select sensor type 7-403 Sensor checking Choose impedance, asymmetry

or slope 7-504 Display resolution Select 0,1 of 0,01 pH 7-605 Signalling of fail condition Switch burn-out signal 7-706 Stabilisation check Adjust parameters 7-807 Auto return function Switch on or off 7-908 Buffer table (7) Program user tables 7-1009 Buffer table (4) Program user tables 7-1010 Buffer table (9) Program user tables 7-1011 Temperature adjustment Correct cable sensor 7-1112 Manual adjustment ITP, slope Settings for non-standard

and asymmetry potential electrodes 7-1233 Password activation Protecting operation levels 7-1355 Restore default values Erase all user programmed values 7-14

IM 12B6C2-E-H

31

1. Access service

*SERV = Service settings

Access to commissioning mode

Select service function

Move pointer to SERVICE

Confirm selection

2. Enter code to slect required function

Display will show *CODE

Enter access code to select routine


Adjust code for entry

Confirm selection

3. Adjust setting(see individual routines)


Adjust value


Return to step 1 or


7-2. Access to service settings


YES NO MODE

ENT


YES NO MODE

ENT

. . .


YES NO

YES NO

MODE *



MODE

x

NO

YES

>

ENT

^

>

^

ENT

YES

MODE

IM 12B6C2-E-H

32

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

Adjustment : (X.X)

Explanation:The default setting of 000 gives only Nernstlinear compensation for the sensitivity of thesensors and an indication of temperature in°C. The choice of automatic or manual tem-perature compensation has no influence.Setting the code to 01 will give a tempera-ture indication in degrees Fahrenheit (°F) onthe display only. Setting the code to 10 willactivate the extra process compensationcalculation. The coefficient has to be adjus-ted from the maintenance level. Setting thecode to 11 will do the same for indication of°F.

Default: 0.0 = European model0.1 = US model

Process compensation factorIn general the automatic temperature com-pensation according to the Nernst equationwill be sufficient for most pH measurements.In cases where the accuracy is critical an

extra process compensation can be activa-ted. The compensation is expressed by afactor (a) which can be programmedbetween -1.00 to + pH per 10°C (or -0.100to +0.100 pH per °C). To establish the cor-rect factor for your application, proceed asfollows:1. Take a representative sample of your pro-

cess composition.2. Measure the pH (with automatic tempe-

rature compensation to Nernst) at theminimum actual temperature of the pro-cess. Call this pHlow.

3. Heat the sample to the maximum tempe-rature of the process.

4. Measure the pH. Call this pHhigh.

5. Calculate the correct factor (a) from::

(pHhigh - pHlow)a = – x 10

Thigh - Tlow

Example : pHhigh = 8.92 at 30°C

pHlow= 9.20 at 20°C

(8.92 – 9.20)a = – x 10 = + 0,2830 – 20

6. Enter this factor with the correct sign inthe temperature compensations routine§5-4.

ACCESS CODE : 02 (see §7-2)DISPLAY : *T.SENS

Adjustment : (X)

Explanation:The indication here determines which tem-perature sensor is connected to the instru-ment. Check what sensor will be used inyour plant and set the correct number for it.Yokogawa sensors are available with Pt100or Pt1000 resistance elements. The SIGMAPH8-ERG or PH8-EFG use the 5k1NTC-sensor.

Default : 1 = Pt100 DIN

X.X0.X Process compensation inactive1.X Process compensation activeX.0 Temperature in °CX.1 Temperature in °F

X0 Pt10001 Pt100 DIN2 Japanese version3 SIGMA Combi-electrode 5k14 NTC resistor 3k (Balco)

7-3. Temperature function 7-4. Temperature sensors

IM 12B6C2-E-H

33

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

Adjustment : (X.X.X)

Impedance checking is for both sensors*IM.LMT = Impedance limit in kΩ

Explanation:The default setting of 110 has one functiondisabled. Each digit controls one function; 0 = OFF; 1 = ON.

The first (left hand) digit controls the asym-metry potential checking function. Thischecks whether the calculated asymmetryafter calibration is within the -120 to +120mV range of the instrument. If not error E02is generated.

The second (middle) digit controls the slopechecking function. This checks whether thecalculated slope after calibration is within thelimits of 70 to 110 % of the theoretical valueof 59.16 mV/pH at 25°C. If not error E03 willbe generated.

The third (right hand) digit controls the sen-sor impedance checking function. The refe-rence electrode or the reference system of acombined electrode is checked for a highimpedance value pointing to a problem inthe measurement. Also the glass electrodechecking is switched on.

This check only indicates a broken sensor ora wrong glass electrode type. When con-necting other than normal glass electrodesthis checking function can be switched off. Ifthe third digit is set to 1, the next step is toadjust the maximum value which will trip theerror E06.

The default value of 100 kΩ is sufficient formost sensors. The display will show*IM.LMT meaning the impedance limit set-ting value in kΩ. Adjust to a significant valuefor the reference system used and suitablein your process.

NOTE:See §7-12 for ITP settings out of limits

Default :1.1.0 = European model1.1.1 = US model

Limits : Impedance50.0 to 999.0 kΩ

X.X.X0.X.X Asymmetry checking inactive1.X.X Asymmetry checking activeX.0.X Slope checking inactiveX.1.X Slope checking activeX.X.0 Impedance checking inactiveX.X.1 Impedance checking active

7-5. Sensor check

IM 12B6C2-E-H

34

7-6. Display resolution

ACCESS CODE : 04 (see §7-2)DISPLAY : *DISP

Adjustment : (X)

Explanation:The default setting of 1 gives an indication of0.01 pH unit on the display which is themaximum accuracy of the instrument whennormal industrial buffer solutions are used. Insome processes the indication of the lastdigit can be suppressed to give an indicationof 0.1 pH units only. The instrument willmaintain its accuracy at the same level asbefore only the indication is changed!!

Default : 1 = 0.01 pH

7-7. Signalling of fail condition

ACCESS CODE : 05 (see §7-2)DISPLAY : *BURN

Adjustment : (X)

Explanation:Besides an indication at the display in thefield, sometimes an indication of errors in thecontrol room is also necessary. This is possi-ble by sending a special signal over the 2-wire connection to the receiving instrument.A singal of 22 mA is used, because it isoutside the normal analogue range of 4 to20 mA. If at the receiving end an alarm is setto the value represented by 22 mA, it isobvious that the proper action can be takenfrom the control room too . The signal usesthe same convention as used in thermo-couple indication named as burn-out detec-tion.

Default : 0 = OFF

7-8. Stabilization check

ACCESS CODE : 06 (see §7-2)DISPLAY : *iT.SEC en *iPH

Adjustment : Criteria for automaticcalibration stabilizationtime and pH.

Explanation:The criteria for deciding whether a value hasstabilized during calibration is set to a rate of0.02 pH during 5 seconds. Depending onthe specific needs of your sensor systemthis parameter can be changed.

Please keep in mind that changing bothvalues will not always change the criteria i.e.0.02 pH/5 s=0.04 pH/10 s=0.10 pH/25 setc. If the system has not stabilized an errorE02 will be generated.

Default : 0.02 pH/5 seconds.

X0 0.1 pH displayed1 0.01 pH displayed

X0 UIT1 AAN 22 mA steady signal on fault.2 AAN 22 mA pulse during 30 s at start

of fault then normal output.

IM 12B6C2-E-H

35

7-9. Auto return

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

Adjustment : (X)

Automatic return to measu ring when nokeys were pus hed for 10 minutes.

Explanation:As a safeguard against long maintenancejobs or inadvertently pushing a button it ispossible to let the system return to its nor-mal function of measurement when no keysare pushed for 10 minutes. When you haveactivated Hold and entered a routine thesystem will return to measurement after 2x10 minutes.

Default : 1 = ON

7-10. Buffer tables

ACCESSCODE : 08, 09, 10 (see §7-2)DISPLAY : *BUF.ID

The following tables can be changed by theuser.

Explanation:There are 3 separate buffer tables in memo-ry. All three tables work in the same way. Asa default all buffer tables are set to the nomi-nal values of 7.00, 4.00 and 9.00 for all tem-peratures between 0 and 50°C. The firstthing to do if you want to use your ownbuffer tables is to program the values ofthese tables. The first thing you will see is*BUF.ID: buffer identity number. As a defaultit is set to the same value as the pH used inthe table. You can change it to indicate achange you made. After pushing ENT youwill be prompted with the first buffer value at0°C. By choosing NO you will skip to thenext value.

By choosing YES you can adjust the valueto your wishes. The next value is 5 °C andthen on to 50 °C in 5 ° steps. Examples ofcommercially available buffer solutions arementioned in the literature.

NOTES: 1. It is not necessary to program every sin-

gle value of the table. 2. By pushing NO, values are skipped; the

system will use interpolation betweenvalues.

3. The two digit number entered as BUF.IDis shown in the calibration routine afterCAL....

X0 OFF1 ON

Servicecode 08 09 10BUF.ID 07 04 090 °C 6.98 4.01 9.465 °C 6.95 4.01 9.39

10 °C 6.92 4.00 9.3315 °C 6.90 4.00 9.2720 °C 6.88 4.00 9.2225 °C 6.86 4.01 9.1830 °C 6.85 4.01 9.1435 °C 6.84 4.02 9.1040 °C 6.84 4.03 9.0745 °C 6.83 4.04 9.0450 °C 6.83 4.06 9.01

IM 12B6C2-E-H

36

7-11. Temperature adjustment

ACCESS CODE : 11 (see §7-2)DISPLAY : *T.ADJ

Adjustment : Correction for cableresistance

Explanation:The temperature measurement is a two wireresistance measurement. In this kind ofmeasurement the length of the connectingcable can influence the accuracy of the tem-perature indication. To compensate for theextra resistance of the cable up to 551 canbe calibrated. Connect the correct tempera-ture sensor to the EXA instrument and insertit in a stable temperature bath of a knownvalue. Check the temperature indicated atthis setting in °C and adjust the value ifnecessary. Now the EXA transmitter hasbeen calibrated to compensate for the cableresistance.

7-12. Manual adjustment of ITP, slopeand asymmetry potential

ACCESS CODE : 12 (see §7-2)DISPLAY : *ITP, *SLOPE, *ASPOT

Adjustment : Set the value of theisothermal point ofintersection (ITP),slope and asymmetry-potential.

Explanation:The EXA PH200 can be programmed for pHelectrodes that do not have a standard ITP(0 mV point) at pH 7.

In some applications special pH electrodesare used (e.g. Emamel, Antimony, etc.)which have a different construction and prin-ciple than standard electrodes. The basicparameters of these electrodes can be pro-grammed in this section The isothermalpoint of intersection (ITP) is the pH-valuewhere the electrode gives 0 mV. The slope isthe sensitivity of the electrode in percent oftheoretical value (59.10 mV/pH at 25°C).The asymmetry potential is the offset in mVof the reference system used.

Defaults : ITP = 7.00 pHSLOPE = 100%ASPOT = 0 mV

Limits : ITP :-1 to 15 pHSLOPE : 70 to 110%ASPOT : -120 to

+120 mVWith checks off:

SLOPE : 25 to 199%ASPOT : -199 to

+199 mV

IM 12B6C2-E-H

37

7-13. Pasword protection by three digitcode

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

Adjustment : (X.X.X)

Explanation:In some cases a protection of operationlevels is wanted. In this way unauthorizedaccess to any of the 3 levels can be blockedby a simple password. When a password isselected for an operation level, access tothat level can only be obtained after enteringthe password. The display will show a mes-sage *PASS* to indicate the entry of thepassword.

NOTE:# can be a digit from 1 to 9, and it will give aprotection according to the schematic belowof the programmed level.

0 = No password1 = Password is 1112 = Password is 3333 = Password is 7774 = Password is 8885 = Password is 1236 = Password is 9577 = Password is 3318 = Password is 5469 = Password is 847

NOTE:For the Maintenance and Commissioninglevel the password entry is always requestedwhen entering from the measure mode.– For the Service level the password entry

is requested after pushing the YES-key– When the Service level protection is acti-

vated, the password cannot be changedby unauthorized persons.

Default : 0.0.0 No password protection

7-14. Restore default settings

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

Adjustment:YES = Erase all programmed values and

replace them by defaults.NO = Keep all programmed values as

before

Explanation:This entry is provided to make it possible tostart from the default values given byYokogawa and thus erase all previously pro-grammed information.

X.X.X0.X.X Protection on Maintenance level

inactiveX.0.X. Protection on Commissioning

level inactiveX.X.0 Protection on Service level

inactive#.X.X Protection on Maintenance level

activeX.#.X Protection on Commissioning

level activeX.X.# Protection on Service level

active

WARNING1. Do not use this code without pro-

per authority as all settings andprogrammed functions will be lost!!

2. Do not enter service codes that arenot mentioned in this booklet.

IM 12B6C2-E-H

38

8. CLASSIFICATION

8-1. Cenelec

Any shunt zenerdiode safety barrier or supply unit or isolated repeater certified by BASEEFA or any EEC approved certification body to [EEx ia] IIC or [EEx ib] IIC where the output current is limited in a different way and not exceeding the follwoing characteristics:Vmax.out = 22 V en Imax.out = 85 mAsuch as (but not limited to): Type : Camille Bauer Sineax 84-2B1-511

Sineax 89-2B1-511 (P.T.B. Cert. Ex-81/2044X)

of

SYSTEM CERTIFICATEEXA200 INSTRUMENTSBASEEFA NR Ex 892380

A) 1 ORP-sensor, such as (but not limited to) SM29-PT8

orA) 1 PH-glass sensor, SM21-AG4

such as (but not limited to) SM21-AG6plus SM21-TL4B) 1 reference sensor SR20-AC22

such as (but not limited to) SR20-AP24or SR20-AL32AB) 1 combined sensor SC21-AGP24

such as (but not limited to) SC21-ASP24plusC) 1 temperature sensor SM60-Pt100

such as (but not limited to) SM60-Pt1000

These are all passive sensors to be regarded as “simple appara-tus” i.e. devices which comply with clause 1.3 van EN 50014.

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

ZONE 1 OR

ZONE 2

Connecting cablessuch as (but not limited to):WU20-PC5 WU20-PC2WU20-PC10 K1220 EMWU-LT2

pH 200 SVout = 14.4 V max.Iout = 3.6 mA max.C ext = 1300 nF maxL ext = 1000 mH max.

BASEEFA Nr. Ex 89C2379

SC 200 SVout = 14.4 V max.Iout = 72.8 mA max.C ext = 1300 nF maxL ext = 8.0 mH max.

BASEEFA Nr. Ex 89C2379

NON HAZARDOUS AREA

Certified Barrier with electronic current limitation and the following characteristics:Vmax.out = 31.5 V, Imax.out = 35 mA, Pmax.out = 1.1 WType : Yokogawa Bard 400 (BASEEFA Cert. Ex 84B2257X)

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

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

of

1 conductivity sensor with SC41-SP34integral temperature sensor SC49-FP08such as (but not limited to) SC41-SP24

SC41-EP14SC41-EP04

These are all passive sensors to be regarded as “simple appara-tus” i.e. devices which comply with clause 1.3 van EN 50014.

Connecting cablessuch as (but not limited to):WU40-LH18 WU40-LH2WU40-LH5

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- +

G

- +

IM 12B6C2-E-H

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Class I, Division I, Groups ABCDVmax = 31.5 VImax = 93.3 mACi = 5 µFLi = 16.5 mH

8-2. FM

A) 1 ORP-sensor, such as (but not limited to) SM29-PT8

orA) 1 PH-galss sensor, SM21-AG4

such as (but not limited to) SM21-AG6plus SM21-TL4B) 1 reference sensor SR20-AC22

such as (but not limited to) SR20-AP24or SR20-AL32AB) 1 combined sensor SC21-AGP24

such as (but not limited to) SC21-ASP24plusC) 1 temperature sensor SM60-Pt100

such as (but not limited to) SM60-Pt1000

These are all passive sensors to be regarded as “simple appara-tus”, i.e. devices which do neither store nor generate voltagesover 1.2 V, currents over 0.1 A, power over 25 W or energy over20 mJ .

pH 200 SVout = 14.4 V max.

Iout = 26 mA max.

C ext = 1 µF maxL ext = 58 mH max.

SC 200 SVout = 14.4 V max.

Iout = 129 mA max.

C ext = 1 µF maxL ext = 2.3 mH max.

NON HAZARDOUS LOCATION

31.5 Vmax4-20 mA

CONTROL DRAWING FOR EXA 200 INSTRUMENTS

HAZARDOUS LOCATION

1 conductivity sensor with SC41-SP34integral temperature sensor SC49-FP08such as (but not limited to) SC41-SP24

SC41-EP14SC41-EP04

These are all passive sensors to be regarded as “simple appara-tus”, i.e. devices which do neither store nor generate voltagesover 1.2 V, currents over 0.1 A, power over 25 W or energy over20 mJ .

Connecting cablessuch as (but not limited to):WU20-PC5 WU20-PC2WU20-PC10 K1220 EMWU-LT210 meters maximum

Connecting cablessuch as (but not limited to):WU40-LH18 WU40-LH2WU40-LH510 meters maximum

FMRC-approved barrier

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

Maximum safe area voltage should not exceed 250 Vrms

+

+–

–

•

•

•

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IM 12B6C2-E-H

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9. CHANGE FROM PH TO ORP MEASUREMENT

The PH200 transmitter can be used for pHmeasurement and tor ORP measurement.The factory delivers the instnument in the pHconfiguration with the possibility to changeeasily to ORP.

9-1. How to change pH measurement toORP measurement

Remove the cover after loosening the 4screws. Now you have access to the elec-tronics. Loosen the 4 screws that hold theboards in place and remove them from theenclosure. On the upper back-side of theDlSPLAY-board there is a blue jumperswitch. Change the springjumper from theupper contact to the lower contact andmake sure that the spring is in its lockedposition to ensure good contact (see figure).

The PH200 transmitter can be reassemblednow, following the opposite sequence as described above. The next step is to reset thememory of the transmitter. The followingsimple procedure must be followed:

1. Push the key marked with *, push the NOkey 2 times till *SERV appears in the mes-sage display, push YES.

2. The display shows *CODE 00; Changethe code 00 to 55 with the arrow keys.Confirm selection with the ENT-key.

3. The display shows ERASE and now theYES key must be pushed.

4. The display shows *SERV. Pushing theMODE key finishes the procedure tomeasure ORP.

9-2. Commissioning the transmitterAs ORP transmitter, the PH200 has basicallythe same functions as explained earlier inthis manual. While commissioning, themicroprocessor will skip its relevant settings.Instead of pH all values and limits areexpressed in mV.

9-3. Maintenance of the transmitterCalibration of the ORP transmitter is a onepoint calibration only. Although there areseveral ORP buffers available, mostly theunit is calibrated with grab sample, analysedon the laboratory with reference method.Automatic temperature compensation forORP is not possible, so the menus AUT.CALand TEMP are skipped during maintenancemenu after pushing the MODE key.

9-4. Special featuresIn many applications the ORP readings aredependent on the pH of the process liquid.In many applications we can eliminate thisinfluence by using a pH electrode as a refe-rence electrode. Due to the high impedanceof the glass electrodes, the electrodes areconnected reverse, resulting in “ - “ readingswhere nor mally “ + “ readings are expected.This does not necessarily influence the ORPcontrol, since the output range is freelyselectable.

pH ORP

IM 12B6C2-E-H

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Reference Calomel Ag/AgCl (1 m) Ag/AgCl (3m) Ag/AgCl (verz.) pH glassORP BUFFER MEDIUMSaturated in 1.68 pH 356 364 393 401 ± 50Chinhydron in 4.0 pH 218 226 255 263 ± 50

in 6.86 pH 49 57 86 94 ± 50in 9.18 pH -87 -79 -50 -42 ± 50

SaturatedHydrochinon in 6.86 pH -50 -42 -13 -5 ± -50ZoBellsolution 187 195 225 232NOTE: all values at 25 °C and tolerance +/- 20 mV

9-6. Buffer values

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Temperature

Temperature

Reference

Liquid earth

Metal (measure)

Shield

Shield

Cable marker

T1 Temperature

T2 Temperature

RE Reference

SE Liquid earth

GE (Measure)

T1 Temperature

T2 Temperature

RE Reference

SE Liquid earth

GE (Measureg)

Red

Black

Red

Blue

Blue

Blue

Red

White

Green

Yellow

Black

Red

ORP/PH-WIRING

ORP/REF-WIRING

Green

Yellow

Red

Transp.

Blue

Yellow

Red

ORP-TRANSMITTER

Combined ORP/pH-electrode

Separate electrodesORP/REF Elektroden

NOTE: reverse mV reading

9-5. Wiring diagram

IM 12B6C2-E-H

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APPENDIX A

Software version 3.0 compared to ver-sions 1 and 2*.In 1994 the software of EXA PH200 hasundergone a major update as result of userfeed back. New features are made accessi-ble by additional Service Codes to avoidprogramming conflicts with users of previousversions.

The new features are:9-1. Call for maintenanceCODE : 13DISPLAY : *CALL.M

Adjustment: (X)

If “1” is selected, the period can be adjusted indays between 1 and 250. Default: 60

Explanation:Company policy may require scheduledmaintenance for pH transmitters. This function will alert the user that the time hascome to perform the scheduled maintenan-ce. This becomes visible on the display byE16 FAIL message. This is one of the advan-ced diagnostic features of the pH200 trans-mitter.

Default: 0

2. Setting limits of asymmetry

CODE : 14DISPLAY : *ASLOW

Adjustment : Set the maximum de-viation from theoreticalzero point. Bothdeviations AS.LOW(-)and AS.HIG(+) are setin dependently.Adjustment can beachieved after activa-ting in access-code03.

Explanation:Most sensors have theoretical 0 mV at 7 pH.Actually these sensors have some off setvoltage which is called 'asymmetry poten-tial'. During calibration EXA corrects thisasymmetry potential. The value of the asym-metry potential is an indicator of the condi-tion of the sensor. Therefore EXA allows theuser to finetune this important diagnostictool. Exceeding the programmed value givesE2 immediately after calibration.

Default : -1 20mV+120 mV

3. Setting limits of slope

CODE : 15DISPLAY : *SL.LOW

Adjustment : The user is promptedto adjust the maxi-mum deviation fromthe theoretical sensiti-vity of a sensor (59.16mV at 25 °C. Both deviationsSL.LOW (-) andSL.HIG (+) are set independently.Adjustment can beachieved after activa-ting in access-code03.

Explanation: pH sensors follow the Nernst equation. However, aged or contaminated sensors willshow a loss of sensitivity. This sensitivity canbe expressed in % of the theoretical valueand is then called 'slope'. To prevent theuser from calibrating a bad sensor, EXA willdisplay E3 immediately after calibration if thecalculated slope exceeds these limits.

Default : 70% low110% high

X0 Not active1 Active

IM 12B6C2-E-H

43

4. Selection of "soft" or "hard" FAIL signalling

CODE : 16DISPLAY : *ERR.01

Adjustment:NO : Error 01 is skipped. Next error is

shownYES : 0 = “soft” alarm

1 = “hard” alarmPressing “ENT" confirms the selection.

Explanation:The self-diagnostics monitor the condition ofsensor and transmitter. Some troubles areless severe than other. EXA allows the userto choose between a "call for maintenance”and a "system failure”. If soft alarm action isselected, the FAIL message flag is flashing.The output functions will not go into “BURN-OUT” position.

If hard alarm function is selected the outputgoes into *BURN-OUT* signal. If program-med that way in service code 30. The FAILflag is shown in the display and the contactfunctions are no longer active.

Defaults:See "Error messages and explanation(Chapter 6-2).

5. New defaults

CODE : 03Adjustment : 1.1.1

CODE : 08, 09, 10Adjustment : NIST Buffers

(formerly NBS)

6. New display messages

E14 : No valid calibrationThe transmitter hasbeen switched frompH to ORP. Resetmemory with code 55.

E16 : Call for maintenanceThe MTBM is expired;cali bration is needed.

IM 12B6C2-E-HSubject to change without noticeCopyright ©

Printed in The Netherlands, 06-707 (A) Q

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