Auto-Ranging Conductivity Controller

auto ranging conductivity controller C7685

The C7685 Conductivity controller with auto-ranging is available in either panel mounting or surface mounting configuration.

C7685 Auto-Ranging Conductivity Controller Introduction

The C7685 Conductivity controller is a precision instrument for reliable, accurate, repeatable and dependable measurement and control of the Conductivity value in many industrial process.

The C7685 is a micro-processor based instrument and as such features a range of options for the accurate control and measurement of conductivity derived measurements.

The C7685 has a wide array of control options including 2 x control relays with On/Off functionality that can be set to High or Low operation. There is a separate alarm relay which can be configured to energise when the conductivity value is outside of parameter. In addition there is a programmable industry standard 4-20mA output which is isolated into 600Ω.

With a 16 character alphanumeric display the C7685 is able to display the conductivity value in either µS, mS or display solution strength in % or Gr/L or Bè for ranges above 20.00mS. The home screen of the C7685 displays the measured parameter, the temperature and the state of the control relays in a single view.

In addition, the operating condition of the conductivity sensor, state of calibration, control points, analogue outputs and alarm setting are easily accessible from the home screen.

In addition the C7685 features auto temperature compensation from a base that is user configurable from 0ºC to 99°C with an adjustable temperature co-efficient from 0-5%.

The C7685 is also an auto-ranging instrument which is perfect for solution strength control applications or where the conductivity value of a measured solution changes of a large range. The instrument will automatically display the range change to ensure that the operator can see the most detailed view of their process.

There are a range of compatible conductivity sensors that work with the C7685 Conductivity Controller. The C7685 is designed to operate with any of the quality AWE 2 wire conductivity cells, an input from a 4 wire electrode cell or an electrodeless or inductive conductivity cell for higher range conductivity measurements.

The C7685 controller is designed for control panel mounting in a 92 x 92mm Din standard cutout and is also available as surface mounting instrument.

The unit operates from a power supply of either 110 VAC or 230 VAC 50/60Hz.

C7685 Conductivity Ranges

The C7685 is able to display the conductivity value over the following ranges, and automatically switch between ranges if the conductivity value should change.

The ranges that correspond to each of the accepted cell constants are listed below:-

Cell ConstantRange 1Resolution 1Range 2Resolution 2Range 3Resolution 3Range 4Resolution 4
K = 0.1 0 - 2.000µS 0.001µS 0 - 20.00µS 0.01µS 0 - 200.0µS 0.1µS 0 - 2000µS 1µS
K = 1.0 0 - 20.00µS 0.01µS 0 - 200.0µS 0.1µS 0 - 2000µS 1.0µS 0 - 20.00mS 0.01mS
K = 10.0 0 - 200.0µS 0.1µS 0 - 2000µS 1µS 0 - 20.00mS 0.01mS 0 - 200.0mS 0.1mS

The C7685 Conductivity Controller is also able to use the input from a 4-wire conductivity cell or from a toroidal conductivity cell with micro-transmitter. The available ranges when working with these cells are listed below:-

Cell ConstantRange 1Resolution 1Range 2Resolution 2Range 3Resolution 3
K = 0.5 0 - 10.00mS 0.01mS 0 - 20.00mS 0.01mS 0 - 40.00mS 0.01mS
K = 1.0 0 - 20.00mS 0.01mS 0 - 200.0mS 0.1mS 0 - 2000mS 1mS
K = 2.0 0 - 40.00mS 0.01mS 0 - 400.0mS 0.1mS 0 - 4000mS 1mS

C7685 With Automatic Temperature Compensation

The C7685 instrument automatically compensates the conductivity value based on the measured temperature of the solution. The temperature compensation can come from a conductivity cell with integrated temperature compensation or from a separate temperature measuring device.

As the C7685 is a precision processing instrument is comes with a wide band of temperature compensation settings. The temperature co-efficient can be set between 0-5.00% per ºC and the base temperature can be set anywhere from 0-99°C.

C7685 4-20mA Output

The analogue output of the C7685 can be configured to either 4-20mA or from 0-20mA as required. The output can be also be set proportionally or inverted to increase granularity or give proportional control to a compatible dosing pump, valve or other compatible control device.

The 4-20mA can be scaled across 2 values within a range. So for instance, in the measuring range of the 0 - 2000µS, the 20mA, a signal could be set at 1000µS to give an analogue current output of 12mA at 500µS.

The 4-20mA current output is isolated to 600Ω and is designed to work with control equipment, PLC's, online Data Loggers, Chart Recorders or any other device that takes an industry standard 4-20mA signal.

C7685 Auto-ranging Conductivity Controller Compatible Cell Constants

The C7685 auto-ranging controller can work with a variety of conductivity cell types, including 2 electrode conductivity cells, 4 electrode conductivity cells, and with electrode-less or toroidal inductive conductivity cells.

The 2 electrode conductive cell constants supported include:-

  • K=0.1 Conductivity Cells
  • K=1.0 Conductivity Cells
  • K=10.0 Conductivity

For 4 electrode conductivity cells, cell with micro-transmitters or toroidal inductive conductivity cells the following constants are supported:-

  • K=0.5
  • K=1.0
  • K=2.0

C7685 Conductivity Controller Set-points and Relays

The C7685 Auto-ranging conductivity controller has 2 x Set-points which correspond to 2 x control relays offering On/Off control. These two control relays are 5 amp non-inductive and can be independently set from one another.

The control relays are also fitted with a user-selectable delay timer where the time can be set from 0-25 seconds as required. In addition the two control relays have an adjustable hysteresis value from ±10% of the set-point.

The C7685 also includes an alarm relay which can be triggered to activate when the measured conductivity value is outside of parameter, with a delay timer of 1 minute. In addition - the alarm relay can be triggered following on from set-point 1 or set-point 2 with an adjustable delay from 0 - 60 mins activation.

C7685 Auto-Ranging Conductivity Controller Summary

The C7685 Controller is a powerful conductivity instrument offering a versatile array of measurement options. The unit is compatible with a wide variety of conductivity cell types and conductivity cell constants including the use of 4 electrode conductivity cells and toroidal or inductive type conductivity cells.

With the measurement units displayed in either conductivity or in solution strength metrics, the C7685 is perfectly suited to industrial measurement and control applications.

C7685 Conductivity Control Specifications

  • Specifications


    Model No:- C7685

    Conductivity Ranges 2 Electrode Cell:- 0 - 2.000µS to 0 - 200.0mS

    Supported 2 Electrode Cell Constants:- K=0.1, K=1.0, K=10.0

    Conductivity Ranges 4 Electrode Cell and Toroidal:- 0 - 10.00mS to 0 - 4000mS

    Supported 4 Electrode Cell and Toroidal Cell Constants:- K=0.5, K=1.0, K=2.0

    Temp. Compensation:- 0-5% user selectable, from base 0ºC to 99ºC

    Temp. Range:- -10ºC to 110ºC

    Set Points:- 2 Min/Max selectable, contact SPST, 5 Amp inductive

    Action:- On/Off with delay timer of 0-25 secs

    Current output:- 0-20/ 4-20mA programmable and isolated into 600Ω

    Zero:- Adjustable

    Slope:- Adjustable

    Mains Supply:- 115 - 230 VAC, 50 / 60Hz switch mode power supply

    Power Consumption:- 5 VA

    Weight:- 850 grams DIN version

    Dimensions:- 96 x 96 x 155mm cutout 91.5 x 91.5mm

  • Features


    • Panel mounting auto-ranging conductivity controller.
    • Precision Conductivity monitoring for process and effluent applications
    • Easy to setup, install and use
    • Full 16 character alphanumeric display showing full soltuion parameters on the home screen and currnet relay states..
    • Two control relays and an alarm relay with easy to configure set-points.
    • Programmable 4-20mA output which is isolated into 600Ω - ideal for connecting to control equipment, PLC's, online data loggers or digital chart recorders.
    • Compatible with a huge range of 2-wire conductivity cells, 4 wire conductivity cells, and toroidal or inductive conductivity cells with a micro-transmitter.
  • Data Sheets

    Data Sheets

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