PH 221 user's manual / EN - xenon.gr

PH 221 - USER'S MANUAL page 1

PH 221

PH 221 / W

INDUSTRIAL

pH CONTROLLERs

USER'S MANUAL

CONTENTS

1. Description..................................................................................................3

2. Technical specifications ...........................................................................5

Schematics .................................................................................................6

3. Installation of the panel instrument........................................................7

4. CH 221 / CH 228 : industrial pH sensors - transmitters.....................8

4.1. Description..........................................................................................8

4.2. Filling the reference electrode ..................................................... 10

4.3. Installation of the type "I" sensor - transmitter ......................... 11

4.4. Installation of the type "T" sensor - transmitter ........................ 14

5. Electrical connections............................................................................ 16

6. Instrument's calibration ......................................................................... 18

6.1. Calibration of the pH measurement ............................................ 18

6.2. Setting the limit value .................................................................... 20

7. Electrodes' maintenance and cleaning .............................................. 21

8. SCL 20 - Automatic electrodes' cleaning system............................. 23

8.1. Description....................................................................................... 23

8.2 Installation of the electrodes' cleaning system ......................... 25

9. ISO 30 / ISO 31 - Analog signals' galvanic isolators....................... 27


Revision 2.4

EN

- The notes and warnings in these operation instructions must be strictly adhered to !

- Maintenance work when the unit is connected to mains may only be carried out byqualified personnel !

- Any faults in the instrument may be remedied with the aid of the instructions givento this user's manual without requiring intervention in the instrument itself.

- Interventions in and modifications to the instrument are impermissible and will voidthe warranty.

- If faults cannot be remedied, the instrument must be removed from service andsecured to prevent accidental start - up.

- Repairs may be performed at the manufacturer's works or by authorised service only.


PH 221 INDUSTRIAL pH - CONTROLLER

1. DESCRIPTION

The industrial pH controller type PH 221, is a precision, modern design instrument, suitable for

continuous measurement and control of the pH in industrial applications.

Common areas of application are :

- Monitoring of the pH in industrial water treatment.

- Measurement and control of the pH in waste water treatment plants (urban and industrial)

- Monitoring of the pH in public waters (rivers, lakes, reservoirs)

- Measurement and control of the pH in industrial applications (Chemical, pharmaceutical and

food industry)

The complete system of the pH controller consists of :

- Instrument type PH 221, suitable for panel mounting, placed in a flame resistant plastic

enclosure (dimensions according to DIN 43700)

or

type PH 221 / W, suitable for wall mounting, placed into a rugged, waterproof housing

(ingress protection IP 65)

- pH sensor - transmitter, which includes the pH and reference electrode, temperature sensor

and an electronic signal preamplifier, suitable for installation in open or closed tanks (types

CH 221 I and CH 228 I) or for bypass tubing (types CH 221 T and CH 228 T)

- Interconnection cable, type CL 200 (standard length 10 m, up to 200 m on request).

The instrument control capability consists on the switching of a relay contact that can drive

directly dosimetric pumps, solenoid valves, light or sound alarm devices or, through a power

relay, high power loads, such as compressors, pumps, stirrers etc.

The set point can be accurately adjusted at any point within the measuring range and is able to

function as a "High" or "Low" limit to the control process, with adjustable dead band (hysteresis)

and time delay on the activation of the output control signal.

The Analogue output section of the instrument features :

- Voltage outputs for the measured pH value (100 mV/pH), temperature (10 mV/°C) and the

difference between the set and the measured value (±200 mV/ÄpH).

- Current output for the measured pH value (4 - 20 mA)

So the instrument can be connected practically to any recorder and, via an analogue to digital

device, to a PLC or a more powerful computer.

In addition to that, it can be connected via the SET - MEASURE output to auxiliary control devices

such as the unit PL 201 (for an additional control point via a relay contact) or the unit PL 214 (pulse

output for proportional control of dosimetric pumps).


The system can measure (and control) the pH level within the range of 0 to 14, with a ±0.01 pH

measurement accuracy and the temperature within the range of 0 to 60 °C, with a ±0.2°C

accuracy.

The instrument displays the pH value in water, compensating the reading automatically for

changes of temperature within the range of 0 to 60 °C.

The 12mm digit high LCD display can be read

easily even from a long distance.

The PH 221 controller may be used with two

types of pH sensors - transmitters :

The type CH 228 ( I or T ) can measure the pH

value from 0 to 14 and the temperature from 0°C

to 60°C.

The type CH 221 ( I or T ) can measure the pH

value from 0 to 14 - lower cost, without tempera-

ture measurement).

All types are provided with a built-in temperature

sensor and compensate the pH reading auto-

matically for temperature changes in the proc-

ess within the operating range (0 - 60°C).

The pH measurement is based on a pH - glass

half cell and a silver / silver chloride reference

half cell. The robust construction and the sensor

design with a separate refillable and renewable

reference electrode, provide extra long service

life with minimum maintenance and reliable op-

eration under conditions that conventional pH sensors fail to operate.

The use of a pH sensor - transmitter with a built-in preamplifier provides :

- Easy installation in tanks or reservoirs (type CH 221 I and CH 228 I) and on pipe networks

in series or by pass (type CH 221 T and CH 228 T).

- The sensor can be installed up to 200 metres away from the panel instrument with no loss

of accuracy or stability and no interference from local electromagnetic fields.

- Easy connection between transmitter and panel instrument with a single cable.

The system becomes stable and accurate within one minute after power on. In case of a sudden

and large change in the measured pH value, the instrument follows smoothly without loss of

stability.

The instrument is to be connected to mains of 230 V ac / 50 - 60 Hz.

CH 221 ICH 228 I

CH 221 TCH 228 T

Figure 1 : pH sensors - transmitters,types CH 221 and CH 228


* The accuracy of the pH control depends on several factors, mainly on the sensor's position and

maintenance, the flow velocity of the water and the calibration of the instrument. This specification

applies only to the instrument.

TECHNICAL SPECIFICATIONS

Á. PANEL INSTRUMENT PH 221

Display : 3 1/2 digit Liquid Crystal Display, 12mm high

Measurement ranges : pH 0 ... 14 pH

Temperature 0 ... 60 °C

Resolution : pH 0.01 pH

Temperature 0.1 °C

Accuracy : pH± 0.01 pH ± 1 digit

(within ± 5°C from calbration temperature)

Temperature ± 0.2 °C ± 1 digit

Temperature compensation Automatic in the range 0 ... 60 °C

Analogue Output : pH 0 ... 1400 mV (+100 mV/pH)

Voltage (± 3 V max) Temperature 0 ... 600mV ( +10 mV / °C )

SET (pH - set) ± 200 mV / ÄpH

Current Analogue Output (4-20 mA) 5mA @ 0 pH / 12mA @ 7 pH / 19mA @ 14 pH

Set point range (pH) 0 ... 14 pH

Dead band range (±) 0.0 ... 1.0 pH

Time delay range 0 ... 3 min

Control accuracy (pH units) * ± 0.05 pH

Switching output load power max 5A / 250V ( 1250 VA)

Operating conditions 0 ... 45 °C / 0 ... 90 % RH

Stability drift < 100ppm /°C, < 0.01% / month

Power requirements 230 V ac (+10 / -15%) / 50 ... 60 Hz

Dimentions / Weight 96 x 96 x 120 mm / 450 gr

Â. pH SENSOR - TRANSMITTER CH 221 ( I - T ) CH 228 ( I - T )

Measurement ranges 0 ... 14 pH 0 ... 14 pH / 0 ... 60 °C

Output signal ± 100mV/pH (±600mV) ±100mV/pH , ± 10mV/°C

pH measuring electrode UWG 1561 (glass)

Reference electrode ER 220 (Ag /AgCl - 3M KCl, refilable)

Temperature compensation Automatic in the range 0 ... 70 °C

pH electrode's input impedance > 1 TÙ

Protection Specification IP 67

Operating conditions 0 ... 60 °C / max 2 bar

Power requirements ± 5V DC / max 5mA (Powered from PH 221 instrument)

Dimensions ** see figure 1 - page 4

Weight Type I : 650 gr / Type T : 450 gr


Figure 2 : pH controller type PH 221 - Front panel

Figure 3 : pH controller type PH 221 - Rear panel

9. Jumper set for the controldirection (low or high)

10. Electrical connections of theinstrument

P1, P2 : Mains connection230V / 50-60 Hz

O1 - O3 : Switching output(relay) contacts

S1 - S5 : Connection of thepH sensor, type CH 228 orCH 221

A1 - A4 : Analogue outputsignals (voltage)

11. Current Analogue Output(4 - 20 mA)

A5 : (+) , A6 : (-)

1. Liquid Crystal Display

2. Selector of the displayed value(pH, Set Point or Tempera-ture)

3. Asymmetry calibration(pH measurement)

4. Slope calibration(pH measurement)

5. Set point adjustment

6. Control (switching) output'sLED indicator

7. Dead band adjustment

8. Time delay adjustment


3. INSTALLATION OF THE INSTRUMENT

The type PH 221 instrument is suitable for panel mounting (along with other instruments). Its

dimensions meet the DIN 43700 specification (see below).

A cutout of 90 x 90 mm (+1mm, -0.5mm) is required for installation on a panel.

The overall dimensions of the instrument are 96 x 96 mm (front) x 120mm (depth).

The standard dimensions allow easy and precise installation of several instruments, horizontally

or vertically with identical openings.

The instrument is easily fixed on the panel by means of the two metal screw clamps which

accompany the instrument (fig. 4b).

After inserting the instrument into the opening, place the two fixing elements by pushing them

gently into place, on the fittings of the two opposite

sides of the instrument. The instrument is secured

onto the panel by fastening the two screws of the

clamps.

The type PH 221 / W instrument is suitable for wall

mounting (ingress protection IP 65).

For outdoor installation, the instrument should not

be exposed to direct sunlight (it is recommended to

use a weather protection cover)

Before installation, remove the lower (non trans-

parent) plastic cover of the panel to reveal the

electrical connections' terminals and the receptions

of the holding screws.

For fixing the instrument, it is recommended to use

the "moving" holder at the middle of the upper part

and two screws at the receptions at the lower part

(fig. 4c).

Figure 4a : Instrument's installation on apanel

Figure 4b : Instrument's fixing withthe screw clamps

Fig. 4c : External dimensions and holdingreceptions of the PH 221 /W instrument


4. CH 221 / CH 228 : Industrial pH sensors - transmitters

4.1. Description

The pH sensors - transmitters types CH 221 and CH 228 consist of a HPVC housing which carries

the glass (pH) electrode, the reference electrode and the temperature sensor at the lower end,

while the upper end is equipped with a waterproof 5 pin connector.

A signal preamplifier is located inside the PVC

housing, sealed with epoxy resin.

This design allows easy installation, connec-

tion with a single cable to the panel instrument

and, due to the built-in preamplifier, accurate

and noise-free operation, even with a 200 m

long cable.

The pH transmitters type CH 221 (I or T) can

measure the pH value from 0 to 14.

The pH transmitters type CH 228 (I or T) can

measure the pH value from 0 to 14 and the

temperature from 0°C to 60°C.

Both types are provided with a built-in tem-

perature sensor and compensate the pH reading

automatically for temperature changes in the

process within the operating range (0 - 60°C).

A pH - glass half cell and a silver / silver

chloride reference half cell are used for the

pH measurement.

The robust construction and the sensor de-

sign with a separate refillable and renewable

reference electrode, provide reliable opera-

tion under conditions that conventional pH

sensors fail to operate.

Our long experience in design, manufacturing

and installation of pH measurement and con-

trol systems, has shown that the reference

electrode accounts for the 70 - 80% of the

problems that arise in the pH measuring

process, because of clogging of the liquid

junction and / or pollution of the internal

electrolyte.

In the most cases the only possible solution isto replace the pH electrode.

1. pH electrode (glass)

2. Reference electrode

3. Liquid junction module ofreference electrode

4. Temperature sensor andglass electrode's protec-tion rods (stainless steel)

5. HPVC body with built-inelectronics (preamplifier),sealed with epoxy resin

6. Electrical connectors

7. Sealing O-ring

8. Waterproof plastic coverof the electrical connec-tors

9. Cable gland

10. Interconnection cable

11. Protection guard for im-mersion type transmitters(type "I")

12. "Ô" adaptor for flow-through mounting ("T"type transmitters)

10

9

8

6

7

5

4

1

2

3

11

12

Figure 5 : pH sensor - transmitters, typeCH 221 (I, T) and CH 228 (I,T)


For this reason we gave extreme care to the reference electrode's design of the CH 221 andCH 228 pH sensors.

The glass fibres type liquid junction, with considerable contacting area, allows free flow of theinternal electrolyte to the solution under measurement, minimizing the clogging problems.

At the same time the flow rate of the referenceelectrolyte is very low (compared with the totalelectrolyte's volume), avoiding the contamina-tion of the internal solution and eliminating the

need of frequent refilling and recalibration.

The lower part of the reference electrode with

the electrolytic liquid junction is removable (fig.

5 -3), providing :

- Easy replacement of the reference filling

solution.

- Easy cleaning, regeneration or replace-

ment (if necessary) of the reference liquid

junction.

- Extra long service life (2 - 5 years) without

replacing the pH electrode.

The CH 221 and CH 228 pH sensors - transmit-

ters are available in two housing types :

The type "I" (CH 221 I and CH 221 I) is suitable

for immersion mounting in tanks and reservoirs.

The type "T" (CH 221 T and CH 228 T) is suitable

for flow - through mounting on pipe networks in

series or bypass.

All types can be connected with the automatic

electrodes' cleaning system, water jet type,

model SCL 20.

* The pH sensors - transmitters type CH 228 É and CH 228 Ô may be used for direct replacement of the

former used CH 227 É and CH 227 Ô sensors - transmitters at all XENON industrial pH controllers (models

PH 221 and PH 227), without any modification.

CH 221 ICH 228 I

CH 221 TCH 228 T

Figure 6 : External dimensions of thepH sensors type CH 221 and CH 228


4.2. Filling the reference electrode

The pH sensors - transmitters type CH 221 and CH 228 (I or T) are shipped and stocked without

filling solution in the reference electrode's chamber.

Before operation, the reference electrode must be filled with the reference electrolyte solution

type BF 121 (3M KCl / sat AgCl), that comes with the sensor.

Unscrew and remove the electrodes' plastic protectionguard from the lower part of the sensor.

Remove gently the protective cap from the glass elec-trode tip. Avoid touching the glass membrane.

Unscrew carefully the liquid junction module at the lowerpart of the reference electrode.

Ensure that the sealing o-ring at theend of the thread of the liquid junctionmodule is slightly lubricated (with sili-cone grease)

Discard the old filling solution (if any) and rinse thereference electrode's chamber first with distilled ordeionized water and then with a small volume of thereference electrolyte.

Fill the reference electrode's chamber with the referenceelectrolyte solution, type BF 121.

Place the liquid junction module to the reference elec-trode, screw carefully until it stops and tighten by hand.

Avoid to touch the glass electrode and the glass fibresof the liquid junction.

Place (screw) the electrodes' plastic protection guard atthe lower part of the sensor.

For the type "T" sensors - transmitters, place the plasticprotection guard to perform the calibration procedure.Then remove the protection guard and fix the sensor -transmitter into the thread of the "T" adaptor (see

chapter 4.4)

The filling solution of the reference electrode should be replaced every 2 - 4 months, depending

on the specific application.

ì


4.3. Installation of the type "I" sensor - transmitter

The type "I" sensor - transmitter is designed for easy installation in open-surface basins and

reservoirs or closed tanks.

For proper performance of the pH sensor, (and the whole system of course) the installer has to

consider the following :

- The location of the pH sensor - transmitter in the tank is of critical importance.

- The pH and the reference electrode (at the lower part of the transmitter) should be

immersed in a depth of 10 to 80 cm below water surface. Special care must be taken that

the water level is not allowed to drop below the measuring electrodes or to raise above the

upper end of the sensor - transmitter.

- Water must flow adequately around the electrodes and be bubble free. When air bubbles

adhere to the electrodes' sensing tips, the instrument indicates erratic pH values.

- The sensor's location on the tank-wall has to be easily accessible and the transmitter must

be easily removable, for convenient maintenance, cleaning and recalibration.

For installation of the type "I" pH sensor - transmitter on the tank wall, it is recommended to use

a metal frame as a sensor holder (see fig. 7 - 2).

For the construction of the holding frame may be used a rectangular cut out profile (approx.

dimensions 20 x 30 mm) from aluminium, galvanised iron or stainless steel.

1

5

3

4

11

4

11

6

8

2

10

7

9

1. pH sensor - transmitter

2. Sensor's metal holding frame

3. Plastic stop- ring

4. Plastic holders for 40 mm PVCrigid tubes

5. Upper permitted water level

6. Lower permitted water level

Connection of the electrodes'cleaning system, type SCL 20

7. Solenoid valve

8. Electrodes' cleaning head, typeSCB 21 I

9. Clean water inlet

10. Plastic tube (PE - 6mm),connecting the cleaning headwith the solenoid valve

11. Holders of the 6mm plastic tube

Figure 7 : Installation of the CH 221 É and CH 228 É sensors in open tanks


To install the type "I" pH sensor - transmitter on the tank wall, proceed as follows :

- Fix the two 40mm plastic tube - holders on the metal frame, 40 - 50 cm apart from each other

(fig. 7 - 4).

- Weld the stop ring on the sensor body in the proper position (fig. 7 - 3), using special adhesive

for PVC - rigid material.

The metal holding frame may be fixed on the tank wall with 2 - 3 screws, as shown at fig. 7.

Then you must connect (if available) the automatic electrodes' cleaning system type SCL 20.

If the pH sensor - transmitter has been ordered with the type SCL 20 electrodes' cleaning system,

the cleaning head and the 6mm tube holders are already fixed on the sensor and the steps 1 - 3

must be omitted.

1. Unscrew and remove the electrodes' plastic protection guard from the lower part of the sensor.

(see fig 5 - 11).

2. Using a special adhesive for PVC - rigid material, fix the type SCB 21 I electrodes' cleaning

head (fig. 7 - 8) at the lower end of the plastic protection guard, so that two (at least) of the

water jets are directed to the glass surface and the glass fibres of the reference electrode.

CAUTION ! Do not block from excess glue the small holes (nozzles) at the inner side of

the cleaning head.

Place (screw) the electrodes' plastic protection guard at its original place at the lower part of

the sensor.

3. Using a special adhesive for PVC - rigid material, fix the two plastic holders of the 6 mm tube

on the sensor's body, aligned with the water inlet of the cleaning head, 40 - 60 cm apart from

each other (fig. 7 - 11).

4. Fix the solenoid valve (fig. 7 - 7) at the outer side of the tank's wall, or at a proper place close

to the sensor.

5. Install and connect the control panel of the type SCL 20 electrodes' cleaning system (see

chapter 8.2).

6. Connect the 6mm water tube (fig. 7 - 10) with the cleaning head and the solenoid valve.

7. Connect the clean water supply (fig. 7 - 9) to the input of the solenoid valve. For proper function

of the automatic cleaning system, the water pressure at the input of the solenoid valve should

be 2 - 4 bar (for output to 6 / 4 mm tube, length 2 - 2.5 m). If the pressure of the clean water

network is higher, it is recommended to connect a control valve in series with the solenoid

valve.

8. Connect the solenoid valve to the 230 Vac output of the SCL 20 control unit.

CAUTION ! Do not activate the cleaning system when the sensor is not immersed into the

water. The pressure of the water jet in air is considerably higher than that in

water and may damage the glass electrode.


For installation of the type "I" pH sensor - transmitter alone on the tank wall (i.e. without the

automatic electrodes' cleaning system) the following procedure is recommended :

- Fix two rings of inner diameter slightly more than 40mm on the tank-wall, 40 to 60 cm apart

from each other, aligned vertically. The rings are to be placed in such way to allow the

transmitter to move freely through them.

- Weld the stop ring on the transmitter in the proper position, using special adhesive for PVC-

rigid material.

After installation, attach the waterproof plug of the CL 200 interconnection cable to the socket

at the top of the transmitter :

a. Unscrew the cable gland of the waterproof plastic cover.

b. Confirm that both O-rings, at the upper part of the sensor and inside the cable gland,

are lubricated properly (silicon grease is recommended).

c. Connect and secure (by its own ring screw) the metal plug on the transmitter.

d. Screw the waterproof plastic cover on the sensor, by hand, tightly.

e. Finally, tighten the cable gland.


4.4. Installation of the type "T" sensor - transmitter

The type "T" sensor - transmitter is designed for installation at pipe networks, connected in series

on the flow or bypass.

For proper performance of the pH transmitter, (and the whole system of course) the installer has

to consider the following:

- The pH sensor - transmitter has to be placed

in a vertical position (a slope of up to 30° is

acceptable), in a location where the water

pressure is kept below 2 bar, the maximum

temperature is up to 60 °C and the flow

velocity is up to 30 cm/sec.

It is recommended to install the sensor (if

possible) close to a free outlet, so that the

pressure is kept as low as possible and

eliminate the risk of momentary pressure

increase (kickbacks) over the sensors' speci-

fied range.

- Water must flow adequately around the elec-

trode and be bubble free. When air bubbles

adhere to the electrode's sensing tip, the

instrument may indicate erratic pH values.

- When the water flow is interrupted, some water must remain into the "T" type sensor's

holder, so that the measuring electrodes remain immersed.

- The sensor's location should be easily disconnected from the flow (using control valves

before and after the "T" type holder) and should be easily accessible, so that the sensor

- transmitter can be easily removed for convenient maintenance, cleaning and recalibra-

tion.

The following method for fixing the pH sensor - transmitter on pipe-networks is recommended:

1. Fix the "T" shaped PVC adaptor, supplied along with the pH transmitter, on the water pipeline

(or on a parallel line connected to it ), using special adhesive for PVC - rigid material.

If the type SCL 20 electrodes' cleaning system is to be used, install the "T" shaped adaptor

that comes with the cleaning system with the cleaning head fixed on it.

2. Confirm that the O-ring at the lower part of the sensor body is lubricated properly (silicon

grease is recommended).

3. Screw the lower part of the transmitter (electrode side) into the thread of the "T" adaptor.

4. Attach the waterproof plug of the CL 200 interconnection cable to the socket at the top

of the transmitter :

a. Unscrew the cable gland of the waterproof plastic cover.

b. Confirm that both O-rings, at the upper part of the sensor and inside the cable gland,

Figure 8 : Installation of the typeCH 221 Ô and CH 228 Ô sensors at pipenetwork.


are lubricated properly (silicon grease is recommended).

c. Connect and secure (by its own ring screw) the metal plug on the transmitter.

d. Screw the waterproof plastic cover on the sensor, by hand, tightly.

e. Finally, tighten the cable gland.

For connecting the automatic electrodes' cleaning system type SCL 20 (if available), proceed as

follows :

1. Fix the solenoid valve at a proper position close to the sensor.

2. Install and connect the control panel of the type SCL 20 electrodes' cleaning system (see

chapter 8.2).

3. Connect the 6mm water tube with the cleaning head and the solenoid valve.

4. Connect the clean water supply to the input of the solenoid valve. For proper function of the

automatic cleaning system, the water pressure at the input of the solenoid valve should be 2

- 4 bar higher than the pressure of the water into the pipe network (for output to 6 / 4 mm

tube, length 2 - 2.5 m). If the pressure of the clean water network is higher, it is recommended

to connect a control valve in series with the solenoid valve.

5. Connect the solenoid valve to the 230 Vac output of the SCL 20 control unit.





5. ELECTRICAL CONNECTION

- The notes and warnings in these operation instructions must be strictly adhered to !

- Maintenance work when the unit is connected to mains may only be carried out by

qualified personnel !

- Any faults in the instrument may be remedied with the aid of the instructions given to this

users manual without requiring intervention in the instrument itself.

- Interventions in and modifications to the instrument are impermissible and will void the

warranty.

- If faults cannot be remedied, the instrument must be removed from service and secured

to prevent accidental start - up.

- Repairs may be performed at the manufacturer's works or by authorised service only.

After fixing the instrument, electrical connections of mains, switching contacts, transmitter and

signal lines are to be made :

- to the terminals on the rear panel of the type PH 221 (panel mounting) instrument - see

page 7, fig. 3 (10, 11)

or

- to the terminals on the terminals' board, under the lower non transparent cover, of the type

PH 221 / W (wall mounting) instrument - see fig. 9 .

1. Connect mains 230 Vac to terminals P1 and P2 (P1: Live, P2: Neutral).

It is recommended that the panel mount instrument is connected to mains via an external fuse

(0.5 A) and an external switch. If there are more than one measuring and control instruments

on the panel, a common fuse may be used, but it is suggested to use individual switches for

every instrument (or group of instruments).

If the mains suffers frequent overvoltage problems ( > 270V ) or voltage fluctuations

( > ±15% ), it is recommended to use a mains voltage stabiliser (or a UPS) or at least, for lower

cost, a mains voltage guard that will interrupt the power supply to the instrument if the input

voltage exceeds 260 Vac.

The instrument is provided with internal voltage stabiliser and protection from momentary

overvoltage - 275V varistor -, but if the mains voltage fluctuates more than ±15% the system

may not function properly. In case that the mains voltage exceeds 270 Vac, a permanent

damage may occur to the instrument.

2. Connect the sensor's interconnection cable (type CL 200) to terminals S1 - S5, according to

the following colour code :

S1 : green (or yell/grn) neg. power supply -5V

S2 : white temperature signal (10mV/°C)

S3 : black (or gray) analogue ground

S4 : brown pH signal (± 700 mV for 0 to 14 pH)

S5 : red (or pink) pos. power supply +5V

(For your convenience the colour code is printed on the rear panel of the instrument as well).


3. Connect the "external command" transfer cable to terminals O1, O2 & O3 according to the

indications on the rear panel.

O1 - O3 : normally open contact (closes on command activation)

O2 - O3 : normally closed contact (opens on command activation)

The relay contacts inside the instrument are specified for currents up to 5A / 250 Vac

(1250VA). If the application requires greater loads, an appropriate power relay is to be

employed.

The switching output (O1 - O3) is internally protected via an internal fast-blow fuse of 6A.

4. Connect the "signal transfer" cables (to recorders, PLC’s or auxiliary control units) to terminals

A1, A2, A3 and A4 ( Voltage analogue outputs ) and / or A5, A6 (4 - 20 mA analogue current

output ), according to the indications on the instrument’s rear panel.

A1 : pH output signal (+100mV /pH , 0 to 1400 mV)

A2 : difference between pH value and set point (pH - SET, ±200mV/ ÄpH)

A3 : Temperature output signal ( 0mV at 0 °C, +10mV /°C )

A4 : Analogue ground of voltage outputs

A5, A6 : 4 - 20 mA current loop output - A5 : (+) , A6 : (-)

WARNING ! USE ONLY SCREENED CABLE for the transfer of the analog output signals.

Shield must be connected either to A4 (analog gnd) or to A6 (V-).

DO NOT SHORT terminals A4 (analogue ground of voltage outputs) with A6

- negative terminal of 4-20 mA current loop - under any circumstances.

DO NOT CONNECT both terminals A4 and A6 to power earth ground (PE)

directly or indirectly, through connection to external devices.

Figure 9 : Electrical connection terminals' board of the PH 221 / W instrument.


6. INSTRUMENT's CALIBRATION

6.1. Calibration of the pH measurement

For proper function, the instrument is to be calibrated with the pH sensor - transmitter in use.

The calibration procedure should be performed in the following cases :

- At start up.

- After electrolyte replacement to the reference electrode.

- At regular intervals during normal operation (every 1 to 3 months, depending on the

application)

The PH 221 controller has a two point calibration capability - i.e. asymmetry (ÄpH ) and slope

(mV/pH).

For instrument calibration, two standard solutions are required:

1. A neutral buffer solution (pH = 7.00 ±0.5).

2. An acid (pH=4.00) or an alkaline (pH=9 or 10) buffer solution.

For the calibration of the instrument, the following procedure is to be carried out:

- Connect the instrument with the pH sensor - transmitter and to mains (see chapter 5, page

16).

- Ensure that the switching output (relay) is not connected to any device under power.

- Ensure that the reference electrode is filled with the reference electrolyte solution (see

chapter 4.2).

- Remove gently the protective rubber cap from the glass electrode tip. Do not touch the glass

electrode's tip and the glass fibres at the lower part of the reference electrode.

- Rinse the electrodes with distilled or deionized water to remove salt deposits on it.

- If the sensor is going to be used for the first time, after a period off service or if the electrode

is just refilled, the electrodes must be reconditioned.

Immerse the electrodes in clean water and let the sensor to operate for 1 to 2 hours before

performing any calibration.

- Make sure that the internal part of the glass electrode is full of internal electrolyte and free

of air bubbles. The air bubbles can be easily removed by shaking the electrode vertically.

- Immerse the lower part of the transmitter (the pH electrode, the reference electrode and

the temperature sensor as well) into the neutral buffer solution (pH=7). It is recommended

that the temperature of the buffer solution is close - within ±10 °C - to the temperature of

the solution to be monitored.

- Set the selector switch (2) on the front panel (fig. 2) to "pH" and wait for a while (5 - 10

minutes) until the displayed value remains constant.

- Using a small screwdriver, adjust the asymmetry - ÄpH - pot (3) for a reading equal to the

pH value of the buffer solution (e.g. 7.00).


- After asymmetry calibration, rinse the electrodes and the temperature sensor with distilled

or deionized water and wipe away adhering drops on them with a soft tissue.

- Immerse the lower part of the transmitter (the pH electrode, the reference electrode and

the temperature sensor as well) into an acid (e.g. pH 4) or an alkaline (e.g. pH 10) buffer

solution. It is recommended that the temperature of the buffer solution is close - within

±10 °C - to the temperature of the solution to be monitored.

Note ! It is a good practice to calibrate the instrument with a buffer solution suitable to

the desired pH level i.e. acid buffer for acid waters and vice versa.

- Set the selector switch (2) on the front panel (fig. 2) to "pH" and wait for a while (5 - 10

minutes) until the displayed value remains constant.

- Using a small screwdriver, adjust the slope - mV/pH - pot (5) for a reading equal to the pH

value of the buffer solution (e.g. 4.00).


6.2. Setting the limit value

The PH 221 controller features a switching output (normally open and normally closed relay

contact) that can be used as a control signal to external devices.

The set point can be adjusted accurately at any value within the measuring range and can function

as an upper or lower limit to the control process. Moreover the instrument offers continuously

adjustable settings for hysteresis (dead band) and time delay on control activation.

The direction of the control limit (upper or lower) is chosen by positioning the short circuit

"jumper", at the rear panel of the type PH 221 instrument (fig. 3 - 9) or at the terminals' board

of the type PH 221 /W instrument, onto the "HI" or the "LO" position.

With the jumper set to the "HI" position, the control contact is activated - and the control indication

LED (6) turns on - when the measured pH value exceeds the set limit value. The opposite occurs

when the measured value drops below the limit value.

If the jumper is set to the "LO" position, the control is "reversed". When the measured pH value

drops below the set point, the control contact is activated (closes) and the control LED (6) on

the front panel turns on. Otherwise, on exceeding the set point, they both turn off (control contact

opens and Led turns off).

To set the control limit, switch the selector (2) on the front panel (fig. 2) to the "SET" position

and, with a small screwdriver, adjust the SET pot (fig. 5 - 5) for indication of the desired value.

To set the hysteresis (dead band) of the control activation, adjust the "dead band" regulator (fig.

2 - 7) to the desired value on the dial printed on the front panel of the instrument. Hysteresis value

can be set from 0 to 1 pH units and defines the distance from the set point where the control

activation or deactivation takes place.

Practically the hysteresis splits the set point in two control points (upper = [set + dead band]

and lower = [set - dead band] ), which are placed symmetrically above and below it. The control

command is activated (or deactivated) when the measured pH reaches the one value and the

opposite occurs when reaching the other.

To set the "time delay" of the control command adjust the "time delay" regulator (fig. 2 - 8) to

the desired value on the dial printed on the front panel of the instrument. The "time delay" feature

prevents false control commands due to momentary changes of the measured value and, in

addition, protects the controlled devices (blowers, pumps etc.), avoiding switching them on and

off within short time intervals.

The time delay value can be set from 0 to 3 minutes.


7. ELECTRODES' MAINTENANCE AND CLEANING

For proper function of the instrument, the pH sensor has to undergo inspection and maintenance

frequently, since it is the most sensitive and critical part of the whole system. It is worth to say

that the pH sensor is the most frequent reason for improper function of the system.

The most common causes for malfunction of the pH sensor are faulty installation and poor

maintenance.

The robust construction and the electrodes' design of the types CH 221 and CH 228 transmitters,

provide, with proper maintenance, extra long service life (2 - 5 years) and reliable operation under

conditions that conventional pH sensors fail to operate.

The electrodes' maintenance is to be carried out as follows:

- Every 1 to 4 days (depending on the application), the pH sensor - transmitter has to be

removed from the basin and washed with clean water - especially the pH and the reference

electrode.

If there are deposits on the glass membrane or on the reference's liquid junction, remove

them by immersing the electrodes in dilute hydrochloric acid or, if the deposits consist of

fatty matter, in a detergent solution for 10 to 20 minutes. Afterwards rinse the electrode

once again with clean water.

Note ! If the sensor is connected with the automatic electrodes' cleaning system type

SCL 20, the above procedure should be performed every 2 - 6 weeks (depending

on the application) and whenever the reference electrode is refilled.

- Every 2 - 4 months, depending on the application, the filling solution of the reference

electrode should be replaced (see chapter 4.2).

- The reference electrode suffers significantly in accuracy and response time if it stays for

some hours in the air and in many cases fails to operate if it remains dry for a longer while

(some days or weeks, depending on the ambient temperature).

If the sensor has remained dry for several hours and a salt deposit has been formatted

around the reference electrode's liquid junction, immerse the electrodes into dilute

hydrochloric acid solution (0.1 - 0.2 M) for half an hour and subsequently in a pH 7 buffer

solution for a few hours. After this treatment, it may be necessary to recalibrate the system.

If the sensor has remained dry for a longer while (days or weeks), remove the salt deposits

with water, replace the reference electrolyte and immerse the electrodes into dilute

hydrochloric acid solution (0.1 - 0.2 M) for half an hour and subsequently in a pH 7 buffer

solution for a few hours. After this treatment it is necessary to recalibrate the system.

- Whenever the sensor is not in use for short periods (up to 2 days), keep the electrodes

wet, preferably immersed in a solution of potassium chloride (KCl 1 to 2M) or in a pH 7 buffer

solution (if not available, use tap water).

- For longer periods of storage, clean the sensor thoroughly (especially the electrodes),

reinstall the protective rubber cap on the glass tip filled with a small quantity distilled or

deionized water, empty the reference electrode's filling solution, rinse the inner side of the

reference electrode and the liquid junction module with deionized water and stock it dry.


- The liquid junction ( the glass fibres ) of the reference electrode is of critical importance

for the proper function of the system - must be whitish and deposit free. The clogging of

the liquid junction results to unstable pH readings, sluggish response on change of the pH

and it is difficult or impossible to calibrate the system.

The design of CH 221 and CH 228 pH sensors permits easy regeneration and cleaning of

the electrode's liquid junction.

If the liquid junction is clogged, unscrew the liquid junction module (fig. 5 - 3), clean the outer

side using a small toothbrush immersed in diluted (~0.1M) hydrochloric acid or warm

detergent solution, rinse with distilled or deionized water and fix it (screwing) again at the

lower end of the reference electrode. When screwing back the liquid junction module, some

pressure is built inside the reference electrode. This so built internal pressure is used to

unblock the liquid junction by forcing a small volume of the internal electrolyte through the

glass fibres and sweeping away any dirt or deposits.

- Generally, there are special ways to clean the pH electrodes and remove deposits from

them, depending on the application. Some are briefly described below:

Inorganic coatings Soak in 0.1 - 0.2 molar HCL

or in 0.1 molar tetrasodium E.D.T.A. solution

Oil, grease Clean with mild detergent or suitable solvent

Protein materials Digest with 1% pepsin in 0.1 molar HCl

Highly resistant Clean with hydrogen peroxide or sodium hypochlorite solution

deposits

- Other, more drastic but risky, methods of replenishment are based on etching the glass

membrane and the liquid junction and include the application of highly corrosive and

dangerous liquids such as hydrofluoric acid , chromo sulphuric acid etc.

CAUTION ! In no case the solutions used for electrodes' cleaning should come in contact

with the inner side of the reference electrode. Whenever the electrodes are

immersed into a cleaning solution, the reference electrode must be filled with

electrolyte and the liquid junction module fixed at its original position.

Use only distilled or deionized water to clean the inner chamber of the

reference electrode.

Do not use halogenated hydrocarbons, acetone, petroleum ether or other

organic solvents that may attack HPVC for cleaning the plastic parts of the

sensor.


8. SCL 20 C / 21 I - AUTOMATIC ELECTRODES' CLEANING SYSTEM

8.1. Description

The pH sensors - transmitters types CH 221 and CH 228 can be connected with the automatic

electrodes' cleaning system, water jet type, model SCL 20C / 21 I.

When the SCL 20 C automatic cleaning system is connected to the sensor, clean water jets are

sprayed at regular intervals on the measuring electrodes, via the solenoid valve and the nozzles

of the cleaning head, forming a water vortex and removing any dirt that may deposit on the

electrodes and may affect the measuring process.

A clean water supply with a pressure 2 - 4 bars is required for the system to operate.

1. Front transparent cover's openingclip (press to open)

2. Mains power switch

3. Button for manual start of theclean cycle

4. Clean cycle's frequency adjust-ment

5. Cleaning duration adjustment

6. Power led indicator

7. Clean cycle's timer led indicators

8. Solenoid valve output led indicator

9. Inhibit output led indicator

10. Cable glands

11. Waterproof plastic cover of theelectrical connections' terminals

12. Plastic cover's fastening screws

13. Terminals for mains 230 Vacconnection

14. Terminals for solenoid valveconnection (230 Vac output)

15. Terminals for inhibit output(switching) connection

16. Electronic circuit's fuse (0.1 Á)

17. Solenoid valve's fuse (6Á)

18. Inhibit output's fuse (6Á)

19. Receptions for the mountingscrews

ELECTRODE CLEANING SYSTEMSCL 20

1/4 2/4 3/4 4/4 INHIBIT CLEAN POWER

CLEAN CYCLE FREQUENCY CLEANING DURATION

MANUAL

hours

43

2

1

6

9

1.5

0.5

12

18

24min

0.5

1

1.5

2

2.5 3

3.5

4

4.5

5

1

3

12

11

26897

4

5

10

14 17 13 161815

19 19

1 2 3 4 5 6 7

Figure 10 : Control panel SCL 20


With the automatic electrodes cleaning system, the maintenance demands of the system are

practically eliminated (daily cleaning is not required and calibration check or recalibration may

be performed at longer intervals), the operating cost is reduced and the overall performance of

the measuring system is improved.

The use of the automatic cleaning system is recommended for applications where the solution

under measurement contains suspended solid particles that have a tendency to deposit on the

electrodes' surface and may result to inaccuracies or even total failure of the pH measurement

system - providing that the addition of a small quantity of clean water during the cleaning

procedure does not affect the process.

The automatic electrodes' cleaning system type SCL 20 C / 21 I or SCL 20 C / 21 T consists of :

- Control panel type SCL 20, suitable for wall mounting, placed into a rugged, waterproof

housing (ingress protection IP 65)

- Electrodes' cleaning head, type SCB 21 I (for immersion type sensors - system type SCL

20 C / 21 I) or type SCB 21 T (for flow through type sensors - system type SCL 20 C / 21 I)

- Solenoid valve and flexible polyethylene tube for the connection with the cleaning head.

The control panel provides :

- Output 230 Vac for direct drive the solenoid valve.

- Adjustment of the clean frequency from 0.5 to 24 hours.

- Adjustment of the duration of the clean cycle from 0.5 to 5 min.

- Capability for manual start of the clean cycle.

- Led indicators of the system operations.

- Auxiliary switching output (inhibit out)

The "Inhibit output" is activated approx. 5 sec before the clean cycle and deactivated approx.

30 sec after the end of the clean cycle. The auxiliary "inhibit output" may be used either to

disconnect during the clean cycle the mains power supply of any external device controlled by

48 14

24

Figure 10a : Water jet type cleaning heads SCB 21 I and SCB 21 T for CH 221 / CH 228pH sensor - transmitters.

SCB 21 I

SCB 21 Ô


the pH meter (as dosimetric pumps, solenoid valves, optical or sound alarms etc.), or as a control

signal to a PLC or a PC, if the pH meter is a part of a process control system.

The relay contacts of the auxiliary output are specified for currents up to 5A / 250 Vac (1250VA).

If the application requires greater loads, an appropriate power relay has to be employed.

The input of the solenoid valve must be connected to the clean water supply. For proper function

of the automatic cleaning system, the water pressure at the solenoid valve's inlet should be

2 - 4 bars, for outlet to a 6 / 4 mm tube, length 2 - 2.5 m. If the pressure of the water supply

network is higher, it is recommended to use a control valve.

The control panel type SCL 20 is to be connected to mains of 230 V ac / 50 - 60 Hz.

8.2. Installation of the automatic electrodes' cleaning system

The type SCL 20 control panel is suitable for wall mounting (ingress protection IP 65)

Before installation, remove the lower plastic cover of the panel (fig. 10 - 11), to uncover the

electrical connections' terminals (13, 14, 18) and the receptions of the holding screws (19).

Fix the SCL 20 control panel on a proper

place. It is recommended to use a small

"hook" type holder at the upper reception

and two screws at the receptions at the

lower part (19).

Fix the solenoid valve close to the sensor

- at the outer side of the tank's wall for

immersion type sensors, or to a steady

place close to the "T" adaptor if the

sensor is installed at a pipe network.

At any case it is suggested that the

length of the 6 / 4 mm polyethylene tube

that connects the solenoid valve's outlet

to the cleaning head does not exceed 3 m.

If the pH sensor - transmitter in use is

immersion type (CH 221 I or CH 228 I) and

has not been ordered with the type SCL 20

electrodes' cleaning system, the cleaning head and the 6mm tube holders must be connected to

the sensor.

- Unscrew and remove the electrodes' plastic protection guard from the lower part of the sensor.

(see fig 5 - 11).

- Using a special adhesive for PVC - rigid material, fix the type SCB 21 I electrodes' cleaning

head (fig. 7 - 8) at the lower end of the plastic protection guard, so that two (at least) of the

water jets are directed to the glass surface and the glass fibres of the reference electrode.

CAUTION ! Do not block from excess glue the small holes (nozzles) at the inner side of

the cleaning head.

Figure 11 : External dimensions and holdingreceptions of the SCL 20 controller


- Place (screw) the electrodes' plastic protection guard at its original place at the lower part of

the sensor.

- Using a special adhesive for PVC - rigid material, fix the two plastic holders of the 6 mm tube

oh the sensor's body, aligned with the water inlet of the cleaning head, 40 - 60 cm apart from

each other (fig. 7 - 11).

If the pH sensor - transmitter in use is a flow through type (CH 221 T or CH 228 T), you must

install the "T" shaped adaptor that comes with the cleaning system and is provided with the

cleaning head (see chapter 4.4).

- Connect the 6mm water tube with the cleaning head and the solenoid valve.

- Connect the clean water inlet to the input of the solenoid valve. For proper function of the

automatic cleaning system, the water pressure at the input of the solenoid valve should be

2 - 4 bar (for output to 6 / 4 mm tube, length 2 - 2.5 m). If the pressure of the clean water

network is higher, it is recommended to connect a control valve in series with the solenoid

valve.

Then electrical connections are to be made to the terminals at the lower part of the control panel

(see fig. 10 - 13, 14, 15).

- Connect terminals 6 and 7 to mains

(230 Vac / 50 Hz).

- Connect terminals 4 and 5 to the solenoid

valve.

- Connect the auxiliary (inhibit) signal's

line to terminals 1, 2 and 3 according to

the indications on the terminals' label :

1 - 2 : Normally open contact

2 - 3 : Normally closed contact

Fix (screw) the plastic cover at the lower part of the control panel (11) and tighten the cable glands

(10).

Press the lock at the right side of the plastic transparent cover (fig. 10 - 1) and open the control

panel's transparent cover.

Set the time interval between the cleaning cycles to the desired value, turning the frequency

adjustment pot (fig. 10 - 4).

Set the duration of the cleaning process, turning the duration adjustment pot (fig. 10 - 5).

Switch on (press) the "power" button (fig. 10 - 2) to operate the system.

Close the plastic transparent cover of the control panel and press it slightly to lock.

For manually start the cleaning process, press the "manual" button (fig. 10 - 3).




1 2 3 4 5 6 7

L N N L

LINE

POWER

230V /50Hz

TO SOLENOID

VALVE

230V Out

6 A

Fuse

0.1

A F

use

6 A

Fuse

INHIBITOUTPUT

Figure 12 : Electr ical connect ions ofSCL 20 controller.


ISO 30 / ISO 31

2-CHANNEL ANALOG SIGNALS

GALVANIC ISOLATORS

/ 4-20 mA CONVERTERS

USER'S MANUAL

CONTENTS

9.1. Introduction ............................................................................................ 29

9.2. ISO 30 - Description ............................................................................. 30

9.3. ISO 31 - Description ............................................................................. 31

9.4. Installation of the ISO 30 / ISO 31 isolators .................................... 32

9.5. ISO 30 - Electrical connections .......................................................... 33

9.6. ISO 31 - Electrical connections .......................................................... 34

9.7. Technical specifications ....................................................................... 35

Input - output conversion tables .......................................................... 35


ISO 30 / ISO 31

2-CHANNEL ANALOG SIGNALS ISOLATORS / 4-20 mA CONVERTERS

9.1. Introduction

In most industrial applications, the analog output of electrochemical measuring instruments (as

pH, redox, dissolved oxygen and conductivity) must be connected to an external device (i.e.

recorder, PLC, PC or Data logger), that is connected to power earth ground.

At all electrochemical measuring instruments, only the sensor section must be in contact with

the solution under test. In case that any other section of the instruments' electronic circuit comes

in contact with the solution under test, even through a high ohmic resistance, the instrument does

not function properly or fails to operate. It is also possible in a few cases, depending on the

composition of the solution under test, this type of electrical connection to cause undesirable and

non-reversible electrochemical reactions that may destroy the sensor unit.

In almost all industrial applications, the solution under test is into tanks or pipe networks and is

practically connected to the line power's earth via a low ohmic resistance. The devices that are

used for industrial control applications (PLCs, PCs, recorders, data loggers etc.), are also

connected to line power's earth.

For that reason, the analog output of an electrochemical measuring instrument should not be

connected directly to the analog input of a control device, if the control device is not equipped

with an isolated type analog input section, but must be connected via an analog isolation device

as the ISO 30 and ISO 31 analog signals' isolators - converters.

The ISO 30 and ISO 31 isolators - converters may also be used if two or more electrochemical

measuring instruments must be connected to an external device with common negative analog

input (common ground), even though the external device is not connected to the line power's

earth.

Another application of the ISO 30 and ISO 31 isolators - converters is the conversion of the voltage

analog output signal of a measuring instrument to a current signal (4-20mA), so that it is

compatible with the input stage of other devices, or transferred to long distances without any loss

in accuracy. As well known, the maximum distance that a voltage analog signal can be

transferred, using expensive special type cables, is only a few hundred metre, despite a current

4-20 mA analog signal can be transferred to several thousands metre, using lower cost cables

and without any significant loss in accuracy.


9.2. ISO 30 - Description

The type ISO 30 dual channel isolator - converter is suitable for the galvanic isolation and

conversion to 4-20mA output of two voltage input signals, coming from two individual

electrochemical measuring instruments, type PH 221, DO 231, RX 250 or BC 421 (pH, DO, ORP

or EC output), in order to connect them to an external device as recorder, PLC, PC or data logger,

without causing any problem to the measuring instrument.

The type ISO 30 isolator - converter is

provided with two analog inputs.

Both inputs (input 1 and input 2) accept a

0 - 1500 mV voltage analog signal and

may be connected to the pH, DO, ORP or

EC voltage analog output of the type

PH 221, DO 231, RX 250 and BC 421 in-

struments respectively.

Both current (4-20 mA) outputs are gal-

vanically isolated from the input circuit

and are equipped with an electronic over-

load protection circuit, that limits the maxi-

mum output current to less than 25 mA, if

the input signal for any reason exceeds

30% - 40% the maximum expected value


Figure 13 : Schematic diagram of the ISO 302-channel isolator - converter

INPUT STAGE OUTPUT STAGE

Common Gnd (0V)of input signals'

Power Earth (PE)

10kÙIn

put

2In

put

1

Out

put

2O

utpu

t 1

analo

gue

opto

couple

rs

Figure 14 : ISO 30 - 2 channel analog signals' isolator - converter

1. Led indicator

2. Electrical connections of input analog signals

1, 2 : analog input 1 (1 : ground, 2 : +)

3, 6 : Shield connection of the input signals'

transfer cable

4, 5 : analog input 2 (4 : + , 5 : ground)

3. Electrical connections of output analog signals

and line power

7, 8 : current output 1 ( 7 : +, 8 : - )

9, 10 : current output 2 ( 9 : +, 10 : - )

11 : Shield connection of the output signals'

transfer cable

12 : Line power earth (PE)

13, 14 : Mains connection 230V / 50 - 60 Hz


9.3. ISO 31 - Description

The type ISO 31 dual channel isolator - converter is suitable for the galvanic isolation and

conversion to a 4-20mA output signal of the two voltage output signals of the type PH 221

pH - controller (pH and °C output), in order to connect them to an external device, as recorder,

PLC, PC or data logger, without causing any problem to the measuring instrument.

The type ISO 30 isolator - converter is

provided with two analog inputs.

Input 1 accepts a 0 - 1500 mV voltage

analog signal and may be connected to

the pH voltage analog output of the PH 221

controller.

Input 2 accepts a 0 - 750 mV voltage

analog signal and may be connected to

the temperature voltage analog output of

the PH 221 controller.

Both current (4-20 mA) outputs are gal-

vanically isolated from the input circuit

and are equipped with an electronic over-

load protection circuit, that limits the maxi-

mum output current to 26 - 28 mA, if the

input signal for any reason exceeds 40%

- 50% the maximum expected value.


Figure 15 : Schematic diagram of the ISO 312-channel isolator - converter

INPUT STAGE OUTPUT STAGE

Common Gnd (0V)of input signals'

Power Earth (PE)

10kÙ

Inpu

t 2

Inpu

t 1

Out

put

2O

utpu

t 1

analo

gue

opto

couple

rs

Figure 16 : ISO 31 - 2 channel analog signals' isolator - converter

1. Led indicator

2. Electrical connections of input analog signals

1, 6 : Shield connection of the input signals'

transfer cable

2, 3 : analog input 1 (1 : ground, 2 : +)

4, 5 : analog input 2 (4 : + , 5 : ground)

3. Electrical connections of output analog signals

and line power

7, 8 : current output 1 ( 7 : +, 8 : - )

9, 10 : current output 2 ( 9 : +, 10 : - )

11 : Shield connection of the output signals'

transfer cable

12 : Line power earth (PE)

13, 14 : Mains connection 230V / 50 - 60 Hz


9.4. Installation of the ISO 30 / ISO 31 isolator - converters

The type ISO 30 and ISO 31 isolators - converters are suitable for rail mounting on a 35mm rail

(TS35) inside an electrical panel. Their dimensions meet the DIN EN 50022 specification.

The overall dimensions of the device are 55 x 75 x 110 mm (see figure 17).

The standard dimensions and the instrument's

design allow easy and precise mounting of many

units in series (horizontally or vertically) on a TS

35 rail, inside an electrical panel.

The instrument is easily fixed on the TS 35 rail by

means of the small holders and the black plastic

clip at the rear side.

For mounting the device on the metal rail, tempo-

rarily hang it on the rail, using the two holders at

the upper part of the rear side (see fig. 18 - Á).

Insert a flat head, medium size, screwdriver into

the reception at the lower part of the rear side and

pull down gently the black plastic clip.

Then, still holding down the plastic clip, push

slightly the device towards the rail and release the

plastic clip (see fig. 18 - Â), so that the device is

fixed on the rail.

Figure 18 : Intrument's mounting on aTS 35 rail.

B

TS 35

A

Figure 17 :External dimensions of the ISO 30 and ISO 31 isolator - converters


9.5. ISO 30 - Electrical connection

After fixing the instrument on the TS 35 rail, electrical connections of mains, input and output

signals are to de made to the terminals at the upper and lower part of the frond side of the device

(see page 34, figure 14 - 2, 3).

1. Connect mains 230 Vac to terminals 13 and 14 ( 13 : neutral, 14 : live) and line power's

earth (PE) to terminal 12.

- It is recommended to connect the ISO 30 isolator - converter to mains from the same

power line with the measuring instruments that are connected to the device, via the same

external fuse and external switch.

2. Connect terminal 2 ( + of input 1) to the terminal Á1 of measuring instrument "1" - (DO 231,

PH 221, RX 250 or BC 421 - voltage analog output, pH, DO, Redox or EC signal

respectively).

3. Connect terminal 1 (gnd of input 1) to the terminal Á4 of measuring instrument "1" -

(DO 231, PH 221, RX 250 or BC 421).

4. Connect terminal 4 ( + of input 2) to the terminal Á1 of measuring instrument "2" -

(DO 231, PH 221, RX 250 or BC 421 - voltage analog output, pH, DO, Redox or EC signal

respectively).

5. Connect terminal 5 (gnd of input 2) to the terminal Á4 of measuring instrument "2" -

(DO 231, PH 221, RX 250 or BC 421).

Note ! Terminal 1 (gnd of input signal 1) and terminal 5 (gnd of input signal 2) are internally

connected via a 400kÙ resistance, as shown at the instrument's schematic diagram

- figure 13. This type of connection allows the interconnection of two input signals,

coming from two individual electrochemical measuring instruments, without causing

any undesirable interference to the measuring circuit.

6. Connect the "signal transfer" cables (to recorders, PLC’s or auxiliary control units) of the

isolated analog output "1" to terminals 7 and 8, according to the indications on the instrument’s

frond panel : 7 : (+) 8 : (-)



frond panel : 9 : (+) 10 : (-)

WARNING ! USE ONLY SCREENED CABLE for the transfer of the input and output analog

signals, even for the connection between instruments that are mounted in the same

electrical panel.

The shield of the analog signals' transfer cables towards and from the ISO 30

isolator - converter, must be connected to :

- Terminal 3 and / or terminal 6 for the input signals.

- Terminal 11 for the output signals.


9.6. ISO 31 - Electrical connection

After fixing the instrument on the TS 35 rail, electrical connections of mains, input and output

signals are to de made to the terminals at the upper and lower part of the frond side of the device

(see page 35, figure 16 - 2, 3).

1. Connect mains 230 Vac to terminals 13 and 14 ( 13 : neutral, 14 : live) and line power's

earth (PE) to terminal 12.

- It is recommended to connect the ISO 31 isolator - converter to mains from the same

power line with the measuring instruments that are connected to the device, via the same

external fuse and external switch.

2. Connect terminal 2 ( + of input 1) to the terminal Á1 of the PH 221 measuring instrument

(voltage analog output, pH signal).

3. Connect terminal 4 ( + of input 2) to the terminal Á3 of the PH 221 measuring instrument

(voltage analog output, temperature signal).

4. Connect terminal 3 or terminal 4 (gnd of input signals) to the terminal Á4 of the PH 221

instrument (gnd - 0V).

Note ! Terminal 3 (gnd of input signal 1) and terminal 4 (gnd of input signal 2) are internally

connected, as shown at the instrument's schematic diagram - figure 15.

If both input signals come from the same measuring instrument, connect only one

of the two gnd terminals (3 or 4) to the ground terminal (A4) of the measuring

instrument.

If the two input signals come from two individual measuring instruments, and of

course under the condition that a gnd - gnd connection between the two measuring

instruments will not cause any undesirable interference to the measuring circuits,

both terminals 3 and 4 must be connected to the ground terminals (A4) of the two

measuring instruments respectively.



frond panel : 7 : (+) 8 : (-)



frond panel : 9 : (+) 10 : (-)

WARNING ! USE ONLY SCREENED CABLE for the transfer of the input and output analog

signals, even for the connection between instruments that are mounted in the same

electrical panel.

The shield of the analog signals' transfer cables towards and from the ISO 31 isolator

- converter, must be connected to :

- Terminal 1 and / or terminal 6 for the input signals.

- Terminal 11 for the output signals.


9.7. Technical specifications

Type .................................................................... ISO 30 .................. ISO 31

Input channels ................................................... 2 ................................... 2

Analog inputs channel 1 : ......... 0 - 1500 mV ............... 0 - 1500 mV

channel 2 : ........ 0 - 1500 mV ............... 0 - 750 mV

Max input Voltage ............................ ± 100 V (channels 1 & 2)

Analog outputs channels 1 & 2 : 4 - 20 mA

(see tables 3 & 4)

Max output load resistance ............................. 450 Ù (channels 1 & 2)

Input - output galvanic isolation ..................... .... > 20 GÙ , > 1 kV

Output current accuracy .................................. ± 10 ìÁ

Max output current (internally limited) .......... 25 mA

Operating conditions ......................................... 0 - 45 °C / 0 - 90% RH

Stability ............................................................... drift < 100 ppm/°C, < 0.01% / month

Power requirements ......................................... 230 V ac ±15% / 47 - 63 Hz

External dimensions.......................................... 55 x 75 x 110 mm

Weight ................................................................. 300 g

Protection specification .................................... ÉÑ 40

TABLE 3

ISO 30 : Outpu t cur ren t ( m A ) vs I npu t Vo l t age (mV)

Channe l 1 / Channe l 2

DO 2 3 1 ( i n : DO ) PH 2 2 1 ( i n : pH ) RX 250 ( i n : mV ) B C 4 2 1 ( i n : E C )

Input Outpu t Input Outpu t Input Outpu t Input Outpu t

0 ppm 5 m A 0 pH 5 m A 0 m V 5 m A 0 % f . s . 5 m A

5 ppm 1 0 m A 7 pH 1 2 m A 5 0 0 m V 1 0 m A 25 % f . s . 1 0 m A

10 ppm 1 5 m A 14 pH 1 9 m A 1 0 0 0 m V 1 5 m A 50 % f . s . 1 5 m A

15 ppm 2 0 m A 1 5 0 0 m V 2 0 m A 75 % f . s . 2 0 m A

TABLE 4

ISO 31 : Outpu t cur ren t (mA) vs Inpu t Vo l tage ( m V )

Channe l 1 Channe l 2

DO 2 3 1 ( i n 1 : DO ) PH 2 2 1 ( i n 1 : pH ) RX 250 ( i n 1 : mV ) in 2 : Tempe ra t u re

Input Outpu t Input Outpu t Input Outpu t Input Outpu t

0 ppm 5 m A 0 pH 5 m A 0 m V 5 m A 0 ° C 5 m A

5 ppm 1 0 m A 7 pH 1 2 m A 5 0 0 m V 1 0 m A 25 °C 1 0 m A

10 ppm 1 5 m A 14 pH 1 9 m A 1 0 0 0 m V 1 5 m A 50 °C 1 5 m A

15 ppm 2 0 m A 1 5 0 0 m V 2 0 m A 75 °C 2 0 m A

PH 221 user's manual / EN - xenon.gr

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