KROHNE PAC-050 User Manual

07/2008

Installation and
Operating Instructions

OPTISENS
PAC 050

Measuring and control device
for pH and ORP measurements

Manual OPTISENS PAC 050

Content

0. Introduction......................................................................................................................................................................................... 4

0.1 General..................................................................................................................................................................................................................4

0.2 Legal matters.........................................................................................................................................................................................................4

0.3 Safety..................................................................................................................................................................................................................... 5

0.3.1 Documentation symbols......................................................................................................................................................................................... 5

0.4 Features................................................................................................................................................................................................................. 6

0.4.1 Device.................................................................................................................................................................................................................... 6

0.4.2 Controller................................................................................................................................................................................................................ 6

0.4.3 Connections........................................................................................................................................................................................................... 6

1. Mechanical installation......................................................................................................................................................................7

1.1 Installation of panel-mounting converters.............................................................................................................................................................. 7

1.2 Installation of wall-mounting converters.................................................................................................................................................................8

2. Electrical connection..........................................................................................................................................................................9

2.1 Connection diagram panel-mounting converter................................................................................................................................................... 10

2.2 Connection diagram wall-mounting enclosure..................................................................................................................................................... 11

3. Operation of the device.................................................................................................................................................................... 12

3.1 How to adjust parameters.................................................................................................................................................................................... 12

3.1.1 Selection between alternatives............................................................................................................................................................................ 12

3.1.2 Adjustment of numerical parameters...................................................................................................................................................................13

3.2 Menu Overview.................................................................................................................................................................................................... 13

3.2.1 Main menu and basic settings .............................................................................................................................................................................13

3.3 Password and language ......................................................................................................................................................................................14

3.3.1 Enter password.................................................................................................................................................................................................... 14

3.3.2 Language............................................................................................................................................................................................................. 14

4. Adjustments for the measurement.................................................................................................................................................14

4.1.1 Measurement....................................................................................................................................................................................................... 15

4.2 pH measurement.................................................................................................................................................................................................. 15

4.3 ORP measurement.............................................................................................................................................................................................. 15

4.4 Calibration............................................................................................................................................................................................................ 16

4.4.1 Calibration procedure........................................................................................................................................................................................... 16

4.4.2 Buffers..................................................................................................................................................................................................................16

4.5 Temperature compensation................................................................................................................................................................................. 17

4.5.1 Calibration of the temperature measurement ...................................................................................................................................................... 17

5. Adjustments of the controller..........................................................................................................................................................17

5.1 ON/OFF controller................................................................................................................................................................................................ 18

5.2 P / PI controller as impulse-frequency controller .................................................................................................................................................19

5.3 P / PI controller as pulse-pause controller...........................................................................................................................................................19

5.4 Activation and deactivation of the controller ........................................................................................................................................................20

5.5 Turn-on delay....................................................................................................................................................................................................... 20

5.6 External controller stop........................................................................................................................................................................................20

5.7 Manual operation of the relays.............................................................................................................................................................................21

5.8 Limit values.......................................................................................................................................................................................................... 22

5.8.1 Turn-on delay....................................................................................................................................................................................................... 22

5.9 Dosage check......................................................................................................................................................................................................22

6. Alarm..................................................................................................................................................................................................23

6.1 Error messages.................................................................................................................................................................................................... 24

7. Output................................................................................................................................................................................................24

7.1 Current output...................................................................................................................................................................................................... 25

7.2 Serial interface RS485 (option)............................................................................................................................................................................ 25

8. Operation and maintenance............................................................................................................................................................25

8.1 Maintenance of the device................................................................................................................................................................................... 25

8.2 Display contrast.................................................................................................................................................................................................... 25

8.3 Exchange fuse.....................................................................................................................................................................................................25

8.4 Cleaning............................................................................................................................................................................................................... 25

8.5 Maintenance of the pH or ORP measurement.....................................................................................................................................................26

8.6 Disposal...............................................................................................................................................................................................................26

8.7 Service................................................................................................................................................................................................................. 26

8.7.1 Product info.......................................................................................................................................................................................................... 26

8.7.2 Analog inputs.......................................................................................................................................................................................................26

8.7.3 Erase settings (reset)...........................................................................................................................................................................................26

OPTISENS PAC 050 2

Manual OPTISENS PAC 050

9. Technical data................................................................................................................................................................................... 27

9.1 Technical data......................................................................................................................................................................................................27

9.2 Dimensions..........................................................................................................................................................................................................28

9.2.1 Panel-mounting enclosure...................................................................................................................................................................................28

9.2.2 Wall-mounting enclosure ..................................................................................................................................................................................... 28

10. Device return form............................................................................................................................................................................ 29

11. Customer settings - for reference...................................................................................................................................................30

3 OPTISENS PAC 050

Manual OPTISENS PAC 050

0. Introduction

0.1 General
This manual applies to the following devices:

It contains technical information for the installation, start-up and maintenance. If you have any questions not

0.2 Legal matters

Device and type Revision date

AC 050 pH/ORP P 06 / 05
AC 050 pH/ORP W 06 / 05

included in this manual please contact your supplier or the official representative of KROHNE Water Solutions
in your country.

Authorized personnel

Installation, connection, adjustment, start-up, and maintenance of the device are carried out by authorized
personnel with adequate qualification.

Liability

Responsibility as to suitability and intended use of these devices rests solely with the user. Improper
installation and operation may lead to loss of warranty. In addition, KROHNE Group's Standard General
Conditions of Sale and Delivery, found on the back of the invoice and forming the basis of the purchasing
contract, are applicable.

General limitation on liability

Unless otherwise expressly set forth in the Standard Terms and Conditions of Sale and Delivery, the Seller is
only liable for damages, whatever their legal basis is, in case they are based on willful action or gross
negligence. This limitation on liability does not apply in the event the Buyer raises claims relating to personal
injury or damages to property according to the product liability law based on a defect of the delivered goods.

Any advice given by the Seller, in particular regarding the application of the delivered goods, shall only commit
the Seller if given or confirmed in writing.

Returning the device

If you need to return the level gauge to the manufacturer or supplier, please read to the instructions and
complete the form given in the appendix.

Warranty

Please consult KROHNE Water Solutions General Terms and Conditions for information on guarantee and
liability.

OPTISENS PAC 050 4

Manual OPTISENS PAC 050

0.3 Safety
Please check for damages immediately after receiving the devices and report any damages within 24 hours to

the delivering company. Never work with a damaged device.
Keep this manual at a safe place where you can always look up the safety instructions and the information on

handling and usage.
This device was designed and built according to the safety measurements for electronic devices and has left

our company in perfect working condition. To preserve this condition and to ensure safe usage follow all
instructions carefully and pay special attention to all warnings issued in this manual. If the device is visibly
damaged or has been stored inappropriately or if there are any doubts concerning safe usage, shut it down
and make sure it cannot be restarted by accident.

0.3.1 Documentation symbols

A set of symbols is used to give warnings or information relevant to particular applications. These are defined
below:

Caution / Attention

Information that, if not followed, may lead to actions resulting in incorrect functioning of the device.

Warning

Information that, if not followed, may lead to actions resulting in measurement error, personal injury and/or

NOTE

damage to the device.

Is used to highlight interesting details.

5 OPTISENS PAC 050

0.4 Features

0.4.1 Device
Measuring ranges

0.4.2 Controller

0.4.3 Connections

Temperature measuring ranges -30.0…+140.0°C
Display measured value with dimension

Temperature compensation manually or automatically with Pt100 or Pt1000
Calibration automatic recognition of the calibration solutions in arbitrary order

Set points 2 set points with adjustable direction
Controller types ON/OFF controller with hysteresis

Hysteresis 0.00…14.00 pH or 0…1500 mV
P range X
Integral time T

Least pulse 0.1…9.9 s
Pulse+ pause time 02…99 s
Impulse frequency 00…72 equiv. to 0...7200 pulses/h
Turn-on delay 0…200 s
Alarm function min. and max. limit and onset delay, power failure alarm,

Dosage control 0…2000 s

Relays 3 potential-free contacts (2x controller, 1x alarm)
Analog output 0/4…20 mA galvanically isolated
Analog inputs 1 measuring input for pH or ORP
Digital input external controller stop or lack-of-water indication

Serial interface (Option) RS 485, Baud rate 9600, data format 8 Bit,

0.00…14.00 pH or 0…1500 mV

P

N

Manual OPTISENS PAC 050

0.00…14.00 pH

-1500…+1500 mV

temperature with dimension
status display sensor, calibration, controller & alarm

P controller as Pulse-Pause-, Impulse-Frequency- or steady controller
PI controller as Pulse-Pause-, Impulse-Frequency- or steady controller

0…2000 s

impulse or permanent signal

6 A, 250 V, max. 550 VA
max. burden 500 Ohm
1 measuring input for Pt100 or Pt1000

1 start and 1 stop bit, no parity

OPTISENS PAC 050 6

1. Mechanical installation

On chapter 9.2 you will find detailed instructions for the installation.

For panel-type meters you have to prepare an opening of 92 x 92 mm / 3.6” x 3.6”. Install the device and fix it
with the two mounting clips which were part of the delivery.

You can install devices in wall-mounting enclosures either by hanging them upon the center slot or by sliding
the slot under a screw, which is an alternative for limited space. Either way you have to fix it additionally with
two screws.

Install the device in a place where it is not put under mechanical or chemical strain!

ATTENTION

1.1 Installation of panel-mounting converters

Mind the protection class:

• Panel mounting version: IP 54 (front), IP 30 (Housing)

• Wall mounting version: IP 65 (closed terminal cover)

Prepare an opening of 92 x 92 mm / 3.6” x 3.6”.

Manual OPTISENS PAC 050

Install the device from the front side and fix it with the
two mounting clips which were part of the delivery.

Screw tight until the device is fixed perfectly.

7 OPTISENS PAC 050

1.2 Installation of wall-mounting converters

Manual OPTISENS PAC 050

Unscrew the terminal cover.

Drill three holes (max. M5) according to the drawing.
Mind that there are two ways for installation:
(1) You can hang the device upon the upper screw.
In that case drill the upper hole 120mm / 4.7” above
the lower two.
(2) Or you can slip the fixture on the back of the
device under the upper screw. In that case the upper
hole has to be another 15mm / 0.6” higher.

Insert the upper screw and make sure to leave at
least 3 mm between wall and screw head for the
fixture.

Mount the device and fix it with the two lower
screws. Close the terminal cover or start with the
connections.

OPTISENS PAC 050 8

2. Electrical connection

ATTENTION

You will find a detailed connection diagram on the following pages.
Before connecting the power supply check the information on the nameplate of the device!
Input, output and control lines must be installed separate from each other and separate from power lines!

For inputs and outputs use screened lines and connect the screen on one side only.
The pH measurement is interference-sensitive. Use a special screened cable and over long distances or in

humid atmosphere additionally an impedance converter.
When using the relays, mind that with inductive loads, interference must be suppressed. If that is not

possible, the relay must be protected at the terminal block in the converter by a resistance-capacitance filter
or, in case of direct current, by a free- wheeling diode.

Manual OPTISENS PAC 050

Current up to Capacitor C Resistance R

60 mA 10 nF 260 V 390 Ohm 2 Watt
70 mA 47 nF 260 V 22 Ohm 2 Watt
150 mA 100 nF 260 V 47 Ohm 2 Watt

1.0 A 220 nF 260 V 47 Ohm 2 Watt

9 OPTISENS PAC 050

2.1 Connection diagram panel-mounting converter

Manual OPTISENS PAC 050

Connection Terminals Notes

1 = reference electrode = screen pH electrode 1 - 2
2 = measuring electrode = core
1 = measuring electrode = core ORP electrode 1 - 2
2 = reference electrode = screen

Impedance converter 1 - 4

Pt 100 5 + 6
Analog output 9 + 10 9 = +, 10 = - max. burden 500 Ohm
Digital input 11 + 12 11 = +, 12 = - External controller stop or lack of water ind.
Relay 1 14 + 15
Relay 2 16 + 17
Relay 3 18 + 19 Alarm relay
Power supply 21+ 22+23 check information given on instrument label
RS485 (option) Sub-D

Sub-D 4/7

Measurement = brown & white
1 = brown, 2 = white
Supplied voltage = yellow & green
3 = yellow = -6V, 4 = green = +6V

3 = +, 8 = ­bridged = terminating impedance activated

OPTISENS PAC 050 10

2.2 Connection diagram wall-mounting enclosure

Manual OPTISENS PAC 050

Connection Terminals Notes

1 = reference electrode = screen pH electrode 1 - 2
2 = measuring electrode = core
1 = measuring electrode = core ORP electrode 1 - 2
2 = reference electrode = screen

Impedance converter 1 - 4

Pt 100 6 - 7
Display contrast Display Potentiometer to adjust the display contrast

Analog output 11 + 12 11 = +, 12 = - max. burden 500 Ohm
Relay 1 14 + 15
Relay 2 16 + 17
Relay 3 18 + 19 Alarm relay
Power supply 20+21+22 check information given on instrument label
RS 485 (option) 23 + 24 23 = 1, 24 = +
Digital input 26 + 27 26 = +, 27 = -, external controller stop or lack-of water indication

Measurement = brown & white
1 = brown, 2 = white
Supplied voltage, yellow & green
3 = yellow = -6V, 4 = green = +6V

11 OPTISENS PAC 050

3. Operation of the device

3.1 How to adjust parameters

3.1.1 Selection between alternatives

When turned on the device shows the measured values of conductivity and temperature together with the
controller mode (Man) and the status of the relays S1 and S2 (both OFF).

With five membrane keys you can move within the menu:

• With key  you enter the main menu.

• With keys  and  you move up and down in the menu.

• With key  you address a menu or parameter.

• With key  you leave a menu without storing

• With key “Enter“, changes are stored.

For your convenience triangles in the display indicate the directions you can take from your position in the
menu.

Temp. comp.
 Manual.

Temp. comp.
 Auto

Temp. comp.
 Manual.

For many parameters you have the choice between two or more alternatives, for e. g. between manual and
automatic temperature compensation. For these parameters you need only key. Switch from one
alternative to the next until you either come back to where you started or until you reach the alternative you
were looking for.

With these parameters any changes are immediately valid - there is no need to store the change.

Manual OPTISENS PAC 050

1 Measured value
2 Status relay 1
3 Status relay 2

F relay OFF
J relay ON

4 Temperature
5 Controller
AUTO: controller ON
MAN : controller OFF
(manual operation of the relays)
6 Orientation aids
7 Key left ()
8 Key up ()
9 Key down ()
10 Key right ()
11 Key “Enter“

1) When you address a parameter the actual setting is displayed.

2) Switch to the next alternative setting with key.

3) When you have come to the last alternative, pressing the key once
more will bring you back to the start.

OPTISENS PAC 050 12

Manual OPTISENS PAC 050

3.1.2 Adjustment of numerical parameters
Numerical parameters can only be altered when a double arrow is visible behind the number. This double

arrow appears when you address the parameter with key.
Adjust the parameter with keys  and . A short pressure on the key changes the last decimal by 1. If you

keep the key pressed, the value will continue changing until the pressure is released.

Store the changes with key „Enter“. The double triangle disappears.

Enter password
 058

Enter password
058 

Enter password
 062

3.2 Menu Overview

6.98 pH 25.0°C

F S1 F S2 Auto



Main menu

Calibrate
Temp. comp. Temperature compensation (only for pH measurements)

Enter password Password function
Set points Controller settings - set points, P ranges, I functions
Limit values

Basic settings
Service
Contr. Settings

Turn-on delay
Analog outputs
Language

Bus address
pH/ORP

3.2.1 Main menu and basic settings

The parameters are sorted into two menus: In the main menu you will find all functions which are used
regularly. The menu basic settings contain all parameters which are set just once during start-up.

On the following pages you will find information on how to adjust parameters and which parameters you
need for which application.

The information follows the following scheme:

1) General adjustments: password and language

2) Adjustments for measurement: calibration and temperature compensation for pH or selection of ORP
measurement

3) Adjustments of the controller: selection of the controller version and corresponding parameters

4) Adjustments to read out data: analog, digitally and/or as alarm

1) Address the parameter with key .

2) A double arrow appears behind the number indicating that the number
can be changed now with keys  and .

3) Store the new value with key „Enter“. The double arrow disappears ­the new value is stored.

Display of the measured values (example)

Press key  to enter the main menu.

Calibration function (only for pH measurements)

Alarm function

Basic settings



Cal. Pt 100
Buffers used

All parameters which are set just once
at the beginning can be found in the
menu “basic settings“

13 OPTISENS PAC 050

3.3 Password and language

3.3.1 Enter password

Main menu

.
.

Enter password
056 Code

To get access to the various parameters you have to enter the correct password:

• Code 11 gives access to the parameters „calibration“, „temperature compensation“, and „set points“.

• Code 86 gives access to all parameters and functions.

With any other number it is impossible to select, view or change any parameter.

Main menu

.
.

Basic settings

3.3.2 Language

For the communication with the device you can choose from a variety of languages.
Since choosing a language is part of the basic settings, it requires code 86. If a different code is set, you will

be asked to enter the correct password.

4. Adjustments for the measurement

Main menu

Calibrate Calibration of the pH measurement, display of slope and zero-point.
Temp. comp.

.
.
.

Basic settings
Buffers used

The instruments can be used for pH or ORP measurements.

Manual OPTISENS PAC 050



Enter password

Basic settings

.



.

Language

Selection between automatic and manual temperature compensation,
adjustment of temperature for manual compensation.

Basic settings



Cal. Temp. Calibration of the temperature measurement.



Language

We speak
English

Adjustment of the calibration solutions and the
inner buffer of the electrode.

OPTISENS PAC 050 14

4.1.1 Measurement

4.2 pH measurement

4.3 ORP measurement

NOTE

Manual OPTISENS PAC 050

Configuration

pH/Redox
Measurement

Displayed is always the actual active configuration. With keyyou can switch from pH measurement to ORP
measurement. Press the key again to go back to the original setting.

pH measurement requires a calibration.
By means of calibration the electrode’s characteristics are determined and stored. The procedure is a

subsequent measurement of two solutions with a known pH. The pH values of the buffers used as calibration
solutions are stored in the menu basic settings.

You have to adjust the calibration data only if you want to use special calibration solutions or electrodes with
a special buffer solution.

The electrode’s slope is influenced by temperature. This influence can be compensated by manual or
automatic compensation. Manual compensation means that the temperature is entered manually. Automatic
compensation requires measuring the temperature with a Pt100 or Pt1000.

ORP measurements do not require calibration or temperature compensation. Therefore the parameters
„calibration“ and „temperature compensation“ do not appear in the menu if ORP measurement has been
selected.

The ORP measurement needs no calibration and no compensation for temperature effects. Therefore these
parameters do not appear in the menu if ORP measurement is selected.



pH/Redox
Measurement



pH/Redox
Measurement

15 OPTISENS PAC 050

4.4 Calibration

4.4.1 Calibration procedure

NOTE

4.4.2 Buffers

Main menu

Calibrate

.

Cal. press & 

.

Slope

.

058 mV/pH
Sensor zero
001 mV

Basic settings
Buffers used  Buffer 1

7.00 pH
Buffer 2

4.00 pH
Sensor buffer

7.00 pH

1) Switch the controller OFF and select manual temperature compensation. Enter the temperature of the
calibration solutions.

2) Immerse the electrode in one of the calibration solutions. Wait until the measured value is stable, then
calibrate by pressing keys and - while still applying pressure - additionally key .
The pH of the calibration solution is now displayed as measured value.

3) Rinse the electrode and repeat step 2 with the second calibration solution.

4) Check the slope and sensor zero-point, then put the electrode back into the armature. Select automatic
temperature compensation and switch ON the controller.

The slope should be close to 59 mV/pH, the zero-point close to 0 mV. The slope decreases and the zero
error increases with time. When either value exceeds certain limits, the instrument displays an error message
indicating that the electrode has to be replaced.

At works the following buffers are stored:

• Calibration solutions: buffer solutions pH 4 and pH 7

• Inner buffer of the electrode: pH 7

If you want to use other calibration solutions, adjust the values - it does not matter if you start with the higher
or the lower pH.

If you are using electrodes with a special inner buffer, adjust the pH value of the sensor buffer, since this
value is used as zero for the calculation of the measured values. You will find the pH of the sensor buffer
printed on the electrode.

Calibrate



Meas. val. 6.99pH

Basic settings

.



Manual OPTISENS PAC 050

The calibration solutions stored as „buffers
used“ are recognised automatically. It does
not matter whether you start with buffer 1
or 2.

Buffers used

OPTISENS PAC 050 16

4.5 Temperature compensation

Main menu

.



Temp. comp. Auto comp. Manual comp.

.
.
.

Basic settings



Select between two ways of compensation:

1) Automatic compensation with temperature sensor
Mind that the temperature sensor should always measure the medium temperature around the sensor. When
pH sensor and temperature sensor are not immersed in the same solution, better switch to manual
compensation.

2) Manual compensation
If the temperature can be regarded as constant, you can enter the temperature manually instead of
measuring it continuously. The device will then compensate the temperature error of this temperature.

4.5.1 Calibration of the temperature measurement

If you connect the temperature sensor with a twin-core cable, slight deviations might occur between
measured and real temperature. These deviations can be eliminated by calibration.

During start-up, measure the temperature manually and enter a correction term so that the display shows the
exact temperature.

5. Adjustments of the controller

Main menu

.
.

Selection of ON/OFF, P or PI controller, adjustment of P ranges and I
Set points

.
.

Basic settings

functions for 2 set points



Contr. settings
For any type of controller you have to enter one or two set points, and you have to tell the device whether

these set points are reached by increasing or decreasing the measured value.

Automatic
compensation

Temp. comp.

Basic settings

Cal. temp.

Manual
compensation



Temp. comp.
Temperature

25.0°C

Calibration
temperature



Cal. temp.

0.0°C

Basic settings

.
.

Adjustment of frequencies and pulse/pause
times, hysteresis, direction of the control
action, delay.

Manual OPTISENS PAC 050

17 OPTISENS PAC 050

5.1 ON/OFF controller

Manual OPTISENS PAC 050

You can choose between three different controller versions:

ON/OFF controller

The ON/OFF controller switches ON if the measured value exceeds the set point and OFF if it drops back
below it or vice versa. Dosage is always carried out with 100% (ON) or 0% (OFF). The parameter for an
ON/OFF controller is the hysteresis.

P controller

The P controller or proportional controller reduces the dosage in the vicinity of the set point proportional to
the control deviation. This is easily achieved if the analog output is used as steady control output. If the
relays are used, the proportional reduction is achieved by either reducing the switch frequency (Impulse­frequency controller) or reducing the time within a given period of time in which the relay is ON (pulse-pause
controller).
The parameters for a P controller are the P range and the impulse- frequency or the pulse+ pause time and
the minimum pulse.

PI controller

The PI controller is a P controller with an additional I function. Adjustments and parameters are the same as
for a P controller. Additionally the integral action time has to be adjusted which determines the I function.
The I function eliminates the P controller’s disadvantage of a remaining steady-state deviation.

Main menu

.
.

Set points

.

7.50 pH controller versions for S1

.

P range S1 and S2

.

0.20 pH

Set points and
controller version



Set point S1 You can choose different

Integral Time S1
000 sec.
Set point S2

6.50 pH
P range S2 Controller settings

0.20 pH

.

Integral Time S2 .
000 sec. Direction S1
raise

Basic settings

Basic settings

.



Lower

.

Contr. settings

Direction S2

Hysteresis



0.01 pH

For an ON/OFF controller you have to set the following parameters:

1) Set points S1 and S2

Set point S1 refers to relay 1, set point S2 refers to relay 2.

2) P range and integral action time for S1 and S2

For an ON/OFF controller set P range = 0 and integral time = 0.

3) Acting direction for S1 and S2

Select “raise“ if the dosage raises the measured value.
Select “lower“ if the dosage lowers the measured value.

4) Optionally a hysteresis

The hysteresis prevents fast switching in the vicinity of the set point. If hysteresis is activated (by setting a
value > 0) the relay switches only when the set point is exceeded by half the hysteresis.

OPTISENS PAC 050 18

Manual OPTISENS PAC 050

5.2 P / PI controller as impulse-frequency controller

Main menu

.
.

Set points

.

7.50 pH controller versions for S1

.

P range S1 and S2

.

0.20 pH

Set points and
controller version



Setpoint S1 You can choose different

Integral time S1
000 sec
Set points S2

6.50 pH
P range S2 Controller settings

0.20 pH Pulse-Freq. S1
Integral Time S2 00*100/4
000 sec. Pulse-Freq. S2
00*100/h

Basic settings

Basic settings

.



.

Direction S2

Contr. settings

Direction S1

Raise



Lower

For an impulse-frequency controller you have to set the following parameters:

1) Set points S1 and S2

S1 refers to relay 1, S2 refers to relay 2.

2) P range and integral action time for S1 and S2

Adjust a P range > 0. For a P controller set integral time = 0, for a PI controller set an integral time > 0.

3) The acting direction for S1 and S2

Select „raise“ if the dosage raises the measured value.
Select „lower“ if the dosage lowers the measured value.

4) Pulse-frequencies for S1 and S2

Enter the maximum pulse-frequency that corresponds to 100% dosage.

5.3 P / PI controller as pulse-pause controller

Main menu

.
.

Set points

.

7.50 pH Different controller

.

P range S1 Controller Settings Versions for S1+S2

.

0.20 pH Pulse-Freq. S1

.

Integral time S1 00*100/h

Set points and
controller versions



Set point S1



You can choose

000 sec Pulse-Freq. S.2
Set point S2 00*100/h

6.50 pH Direction S1
P range S2 Raise

0.20 pH Direction S2
Integral time S2 Lower
000 sec.

Basic settings

Basic settings

.



10 sec

.

Contr. settings

.
.

Pulse+Pause The pulse+pause time

must be at least twice

Least Pulse



0.1 sec pulse time

as long as the least

19 OPTISENS PAC 050

5.4 Activation and deactivation of the controller

For a pulse-pause controller you have to set the following parameters:

1) Set points S1 and S2

S1 refers to relay 1, S2 refers to relay 2.

2) P range and integral action time

Adjust a P range > 0. For a P controller set integral time = 0, for a PI controller set an integral time > 0.

3) Pulse-frequencies for S1 and S2

Both frequencies must be set to 00, otherwise the controller will act as an impulse-frequency controller.

4) The acting direction for S1 and S2

Select „raise“ if the dosage raises the measured value.
Select „lower“ if the dosage lowers the measured value.

5) Pulse + pause time

Define a period of time during which the relay is proportionally to the control deviation ON (pulse) or OFF
(pause), respectively.

6) Least pulse time

Set a minimum pulse time that the relay has to at least remain open to allow the actuator to react.

The controller is activated and deactivated from the main display without any menus. Press key to switch
from Manual Mode (controller OFF) to Automatic Mode (controller ON) and vice versa. The actual mode is
indicated in the display.

Make sure that the controller is deactivated before connecting dosing pumps or other actuators!

Manual OPTISENS PAC 050

WARNING

5.5 Turn-on delay

5.6 External controller stop

NOTE

Main menu

.
.

Basic settings

180 s

Set a delay time which has to pass before the controller is activated after start-up or power interrupt. This
allows the measurement to settle and prevents inappropriate dosage of chemicals.

You can activate or deactivate the controller with an external switch by using the digital input. This feature
requires no settings or adjustments. If the digital input is short- circuited, the controller stops, and the
message „external controller stop“ appears in the display.

This feature can also be used as lack-of water indication. Just connect a level sensor to the digital input.

Basic settings

.



.

Turn-on delay
Turn-on delay
ON
Turn-on delay



Turn-on delay

OPTISENS PAC 050 20

5.7 Manual operation of the relays

6.99 pH 25.0°C

 F S1 F S2 Auto 

6.99 pH 25.0°C

  F S1 F S2 Man 

6.99 pH 25.0°C

   S1 F S2 Man

6.99 pH 25.0°C

  J S1 F S2 Man

6.99 pH 25.0°C

   S1 F S2 Man

6.99 pH 25.0°C

  F S1  S2 Man

6.99 pH 25.0°C

  F S1 J S2 Man

6.99 pH 25.0°C

  F S1  S2 Man

6.99 pH 25.0°C

  F S1 F S2 Man 

For manual operation you need no menu.

• With key  you switch OFF the controller.

• With key  you switch between Manual operation <> operation mode S1 <> operation mode S2 <>

manual operation.

• In the operation mode you can switch ON and OFF the selected relay with key  .

• A flashing square indicates that the relay is in operation mode.

• A dark square indicates that the relay is switched ON.

• A light square indicates that the relay is switched OFF.

If you switch ON a relay it stays ON until you switch it OFF again manually!

Manual OPTISENS PAC 050

1) If the controller is ON, switch it OFF with key  .
Instead of „Auto“ the display shows „Man“.

2) Switch to the operation mode of S1 with key.
The square to the left of S1 starts to flash.

3) Switch ON relay 1 with key  .
The square to the left of S1 gets dark.

4) Switch OFF relay 1 again with key  .
The square gets light.

5) Switch to the operation mode of S2 with key.
The square to the left of S2 starts to flash.

6) Switch ON relay 2 with key  .
The square to the left of S2 gets dark.

7) Switch OFF relay 2 again with key  .
The square gets light.

8) Leave the operation mode of relay 2 with key .
Both squares appear light, none flashes - You have left the operation
mode.

WARNING

21 OPTISENS PAC 050

5.8 Limit values

NOTE

5.8.1 Turn-on delay

5.9 Dosage check

NOTE
NOTE

Manual OPTISENS PAC 050

Main menu

.
.

Limit values

Limit values



Limit S1

8.00 pH
Limit S2

6.00 pH
Turn-on delay
005 sec.

For the alarm, you can adjust two limits:

• Limit 1 is an upper limit. If the measured value exceeds limit 1, an alarm is issued.

• Limit 2 is a lower limit. The alarm is issued if the measured value drops below limit 2.

In case of alarm the display shows the message „limit 1“ (or 2, respectively) and relay 3 is switched ON. This
relay can be used to activate an external horn or lamp.

The limit function is active only if the controller is set on automatic mode. When you switch the controller to
MAN, the alarm is extinguished.

In some applications it happens regularly that the measured value exceeds a limit for a short period of time.
To avoid having an alarm issued under these circumstances you can adjust a turn-on delay which has to
pass before an alarm is issued. If the turn- on delay time is >0 then the alarm is issued only if the cause of
alarm remains longer than the specified turn-on delay time.

Main menu

.
.

Basic settings

Contr. settings

Basic settings

.



.

Controller settings



Dosage check S1
00 min
Dosage check S2
00 min

In the basic settings of the controller you can define, how long a controller is supposed to dose with 100%
without raising alarm.

If the controller output is 100% for more than the specified time, this is interpreted as an indication of failure,
and the device issues an alarm and deactivates the controller, thus stopping further dosage.

The dosage check is a safety catch to prevent hazardous chemicals to be set free in case of a defective
dosing tube or tube connection.

In case of an alarm due to dosage check, only the controller concerned is deactivated.
If you set the dosage check time to 0 min, the dosage check function is deactivated.

OPTISENS PAC 050 22

6. Alarm

Manual OPTISENS PAC 050

Additional to the limit function the device provides various check functions that raise alarm.
In case of an alarm, relay 3 switches, undelayed, and the cause of the alarm is indicated in the display.
If the cause of alarm is such that control is no longer possible or might even be dangerous, the controller is

automatically deactivated until the alarm is switched off.
Switching off the alarm is done automatically by the device as soon as the cause of alarm is eliminated.

Sensor check during measurement

During measurement all connected sensors are checked. If an analog input does not receive a correct signal,
for e. g. if a cable is broken or a sensor damaged, an alarm is issued, and the controller deactivated. Alarm
and controller stop remain until the analog input receives correct signals again.

Sensor check during measurement

During measurement all connected sensors are checked. If an analog input does not receive a correct signal,
for e. g. if a cable is broken or a sensor damaged, an alarm is issued, and the controller deactivated. Alarm
and controller stop remain until the analog input receives correct signals again.

Dosage control

If a controller output is 100% longer than the defined dosage time, an alarm is issued, and the corresponding
controller is deactivated. The alarm remains until the controller output drops below 100% - it can also be
extinguished by setting the controller to manual mode.

Cause of alarm only active in AUTO mode deactivates controller

Slope error no no
Sensor zero no no
Error input 1 no yes
Error input 2 no yes
Limit yes no
Dosage yes yes

23 OPTISENS PAC 050

6.1 Error messages

7. Output

Manual OPTISENS PAC 050

Error message Cause Action

Slope error The slope determined by

calibration was higher than
65 mV/pH or lower than 50 mV/pH.

Please check the sensor connection and
cable, and make sure that the calibration data
stored in the instrument corresponds to the
calibration solutions used. Also make sure that
the temperature settings are correct. Then
repeat the calibration. If the error message
remains, the sensor has to be replaced or
regenerated.

Sensor zero The zero deviation determined by

calibration was higher than 60 mV
or lower than -60 mV.

Please follow the procedure described above.
Make sure that the sensor buffer stored in the
calibration data corresponds to the sensor
used. If the error remains, at least the
reference electrode has to be replaced or
regenerated.

Error input 1 The pH or ORP electrode gives no

signal.

Error input 2 The temperature sensor gives no

signal.

Please check the connections, the cable and
the sensor for signs of damage.
Please check the connections, the cable and
the sensor for signs of damage.
This message also appears if automatic
temperature compensation was selected
although no temperature sensor was used.

Limit 1 / 2 The measured value exceeded

limit 1 (or dropped below limit 2,

Please check the dosing and readjust the
control parameters, if necessary.

respectively).

Dosage Pump 1 (or 2, resp.) feeds with

100% for more than the defined
period of time.

Ext. controller stop The digital input has been short-

circuited.

Please check the dosing, especially the
feeding tubes and connections. Caution!
Carefully check for leaking chemicals!
This only indicates the external controller stop.
If, however, you have connected a level
sensor, this message appears due to the „lack
of water“ alarm.

Main menu

.
.

Basic settings

Analog output

Basic settings

.



.

.

Start 0/4mA

.

End 20 mA

.

Analog output

Analog output



0…20mA/4…20mA

Meas. value

Bus address
Nr. 00

Serial interface

RS485 (option)



Bus address

Set a number
between 0 and 31 to
address the device
via data bus.

OPTISENS PAC 050 24

7.1 Current output

7.2 Serial interface RS485 (option)

You can read out the measured value as 0/4…20 mA signals via the current output.
With the setting 4…20 mA the resolution is lower, but defective cable connections are immediately evident.

With the parameters Begin and End you define which part of the measuring range you want to read out.
Alternatively you can use the current output as steady-state controller output. In that case assign the current

output to controller S1 or S2, respectively.

The devices are available with serial interface RS485 by means of which they can be integrated in a data
bus system. Via the interface, all settings, measured and control values as well as any error messages can
be read out digitally.

Devices with RS485 are automatically delivered with the leaflet „Information on the RS485“ which contains
instructions on the communication and a complete list of the functions available via interface.

8. Operation and maintenance

8.1 Maintenance of the device

8.2 Display contrast

8.3 Exchange fuse

WARNING

The device does not require any maintenance. There is no need for readjustment. If you want to have the
device checked regularly, you are welcome to send it to KROHNE Water Solutions. Alternatively the device
can be checked on site by one of our engineers.

With devices in wall-mounting enclosures the display contrast can be adjusted to the actual light conditions
by means of a potentiometer. It is indicated in the connection diagram with the word „display“.

Devices in wall-mounting enclosures have an internal fuse which has to be replaced at need. You will find a
spare fuse fixed to the inside of the terminal cover. Information on the fuse can be found in the chapter
„Technical data“.

To exchange the fuse, open the front carefully. The fuse is located on the right hand side. It is kept in place
by a Bayonet lock. Turn the lock to the left until the fuse pops up. Exchange it and fix the new fuse by turning
the lock to the right. Put the front back on and fix it tightly.

Disconnect the power supply before opening the device!

Mind that the cable connections to the front are not damaged, broken or torn during the process!

Manual OPTISENS PAC 050

ATTENTION

8.4 Cleaning

25 OPTISENS PAC 050

The front and the display should not get in touch with organic solutions such as methanol. Never let water
get inside the device. We suggest to simply use a damp cloth for cleaning.

8.5 Maintenance of the pH or ORP measurement

The metallic surface of the ORP electrode must be cleaned regularly. pH and reference electrodes change
with time, so their characteristics have to be determined regularly by means of calibration.

NOTE

8.6 Disposal

8.7 Service

8.7.1 Product info

8.7.2 Analog inputs

8.7.3 Erase settings (reset)

The instrument checks the sensor’s characteristic parameters after each calibration and displays an error
message if the sensor has to be replaced. See chapter „Error messages“.

For disposal please notice that the device contains electrolyte capacitors which have to be disposed
separately.

Main menu

.

Unit no.

.

No. 041

.

Software date

.

M/Y 1.00

.

Service
Analog inputs

Input 1 003
Analog inputs
Input 2 25.0°C

Erase settings
Press & 

In this menu you will find information which is especially important for any inquiries, updates or problems.

These figures allow a precise identification of the device (hardware and software).

Here you can see the raw data the device obtains from the sensors. They are not influenced by
compensations or calibration and offer valuable information in case of problems with the measurement or the
device.

If you have problems interpreting this data, send them to your supplier together with the device data and ask
for support.

With this function you can erase all customer settings and restore the original at-works data.
The process takes some 30 seconds. When it is finished the display will show the measured value, and the

controller will switch off.

Manual OPTISENS PAC 050

Product. date



M/Y 1.00



Analog inputs



Erase settings



Service

Product info

OPTISENS PAC 050 26

9. Technical data

9.1 Technical data

Manual OPTISENS PAC 050

Feature PAC 050 R PAC 050 W

Version panel-type converter wall-mounting enclosure
Dimensions (w x h x d) 96 x 96 x 127 mm / 3.8 x 3.8 x 5” 165 x 160 x 80 mm / 6.5 x 6.3 x

3.1”
Weight 0.8 kg / 1.8 lbs 1.0 kg / 2.2 lbs
Terminals screw terminals max. 1.5 mm2 Spring clamp max. 1,5 mm2
Protection class IP 54 (front), IP 30 (housing) IP 65
Power supply 230 V AC +6/-10 %, 50/60 Hz, alternativ 110 V AC oder 24 V AC
Internal fuse none 230 V : 63 mA slow

110 V : 125 mA slow

24 V : 800 mA semi-slow
Power consumption 10 VA 10 VA
Display LCD, 2-line, 2x16 characters, illuminated background

measured value and temperature with dimensions indication of relay

status
Current output 0/4...20 mA, galvanically isolated, max. burden 500 Ohm
Interface (option) RS485, Baud rate 9600, data format 8 Bit, 1 Start and 1 Stop bit
Controller ON/OFF controller with hysteresis, P or PI controller as Pulse- Pause-

or Impulse-frequency controller, steady controller, bidirectional PI

control action, adjustable onset-delay, dosage control function, manual

operation of the relays, controller stop via external switch or level

sensor (lack-of-water sensor)
Set points 2 set points adjustable within the measuring range
Alarm function with min. and max. limit and turn-on delay
Contact rating 6 A/ 250 V, max. 550 VA resistive load (with RC protective circuit)
Operation temperature 0…+50°C / 32…+120°F
Storage temperature -20…+65°C / -5…+150°F
Humidity max. 90% at 40°C /105°F non-condensing

27 OPTISENS PAC 050

9.2 Dimensions

9.2.1 Panel-mounting enclosure

Manual OPTISENS PAC 050

9.2.2 Wall-mounting enclosure

OPTISENS PAC 050 28

Manual OPTISENS PAC 050

10. Device return form

Company:………………………………………………. Address:……………………………………………..
Department:…………………………………………… Name:………………………………………………..
Tel.-No.:……………………………………………….. Fax No.:……………………………………………...
Email:……………………………………………………
The enclosed device
Type:……………………………………………………………………………………………………………………………
KROHNE Water Solutions Order No. or Series No.:………….…………………………………………………………..
has been operated with the following liquid:……………………………………………………………………………….

This device has been carefully manufactured and
tested. If installed and operated in accordance with
these operating instructions, it will rarely present any
problems. Should you nevertheless need to return a
device for inspection or repair, please pay strict
attention to the following points:

Due to statutory regulations on environmental
protection and safeguarding the health and safety of
our personnel, KROHNE Water Solutions may only
handle, test and repair returned devices that have been
in contact with products without risk to personnel and
environment.

This means that KROHNE Water Solutions can only
service this device if it is accompanied by the following
certificate confirming that the device is safe to handle.

S P E C I M E N certificate

Because this liquid is

water-hazardous toxic caustic flammable

we have

checked that all cavities in the device are free from such substances
flushed out and neutralized all cavities in the device

We confirm that there is no risk to humans or environment through any residual liquid contained in this device.

If the device has been operated with toxic, caustic,
flammable or water-endangering products, you are
kindly requested:

to check and ensure, if necessary by rinsing or
neutralizing, that all cavities are free from such
dangerous substances,

to enclose a certificate with the device confirming that
is safe to handle and stating the product used.

We cannot service this device unless accompanied
by such a form.

29 OPTISENS PAC 050

Manual OPTISENS PAC 050

11. Customer settings - for reference

Type ………………. Date of installation ……………….
Serial number ………………. Software version ……………….

Cal. solution 1 ………………...pH
Cal. solution 2 ………………...pH
Sensor buffer ………………...pH

Temperature …………….°C Correction ……………………..°C

Output 1

Start ……………………
End ……………………

Controller S1 Controller S2
Acting direction Acting direction

Set point …………………… Set point ……………………….
Hysteresis …………………… Hysteresis ……………………….
P range …………………… P range ……………………….
Integral time …………………..s Integral time ……………………….s
Pulse + pause time …………………..s Pulse+ pause time ……………………….s
Minimum pulse …………………..s Minimum pulse ……………………….s
Pulse frequency …………….*100/h Pulse frequency ………………...*100/h

Delay time ……………….min.

Limit S1 …………………… Limit S2 ………………………..
Delay time ……………….min.

Bus address ……………………

Device

Measurement

Temperature compensation

Analog output

Controller

Turn-on delay

Alarm

Serial interface RS 485

Identification / location ………………………………………………….

F pH F ORP

F Manual F Automatic

F Pt100

F 0…20mA F 4…20mA

for F pH/ORP
F Controller S1 F Controller S2

F raise F lower F raise F lower

F normally closed F normally open F pulse contact F perm. contact

OPTISENS PAC 050 30