C3655 & SI315

Inductive Toroidal Electrodeless Conductivity Controller

inductive conductivity controller 3655 with toroidal or electrodeless conductivity cell SI315

The SI315 Inductive or Electrodeless Conductivity Cell with the Toroidal Conductivity Controller C3655.

C3655 Inductive Conductivity Control Introduction

The C3655 is a Conductivity Controller designed specifically to work with our toroidal or inductive conductivity cell. (This is sometimes known as an electrodeless conductivity sensor or non-fouling conductivity cell.)

The C3655 is available as a Din Rail mounting unit for installation into a control panel. It is also available within our surface mounting enclosure supplied in W'proof enclosure for surface mounting. The surface mounting toroidal conductivity controller carries part number C3655-W.

As a conductivity controller designed for industrial process control, the C3655 is a precision instrument for reliable, accurate, repeatable and dependable measurement and control of the conductivity value in many industrial process.

For controlling industrial processes, the C3655 includes a set-point and control relay, complete with a user selectable delay timer.  There is also a galvanically isolated 4-20mA output which is isolated into 500Ω and ideal for use with a PLC, digital chart recorder or online Data Logger.

The C3655 includes a large LCD display to show the current conductivity value, along with simple push button and potentiometer adjustments for calibrating the instrument and adjusting the set-points and delay timers.

In addition the C3655 features auto temperature compensation from our SI315 toroidal or electrodeless conductivity cell. The temperature is compensated by 2% per degree centigrade from a base of 25°C.

The C3655 for panel mounting has DIN standard dimensions of (W) 105mm x (H) 100mm x (D) 58mm.  When supplied in a surface mounting enclosure the C3655-W measures (W) 135mm x (H) 170mm x (D) 115mm.

The unit operates from a power supply of either 115 VAC or 230 VAC 50/60Hz.

SI315.1 Inductive or Toroidal Conductivity Cell Introduction

The SI315.1 is a toroidal or inductive electrodeless conductivity cell designed to work with the C3655 Inductive Conductivity Controller.

As a toroidal conducive cell the SI315.1 doesn't have any functional parts in contact with the measured solution.  Instead a combination of toroidally shaped windings stimulate an ionic current and receive an electric current corresponding to the conductivity of the measured solution.

As the toroids aren't in direct contact with the measured solution (hence the name electrodeless conductivity cell), the SI315 is manufactured in PVDF for greater chemical resistance.

The SI315 receives power from the C3655 and is connected using the simple wiring diagram. With wetted parts in PVDF the SI315 is suitable for operation up to 80°C and a pressure of 3 Bar at 20°C

The SI315 is supplied in either a tee-piece or in Dip mounting formation using part number 315.1.

C3655 and SI315 Conductivity Ranges

When working in combination, the SI315 toroidal conductivity cell and the C3655 offer the following measurement ranges and resolutions:-

Range 1Resolution 1Range 2Resolution 2Range 3Resolution 3
0 - 20.00mS 0.01mS 0 - 200.0mS 0.1mS 0 - 2000mS 1mS

C3655 With Automatic Temperature Compensation

The C3655 instrument automatically compensates the conductivity value based on the measured temperature of the solution. The temperature compensation is supplied via the SI315 ensuring compatibility and accurate temperature measurement.

C3655 4-20mA output

The C3655 produces an analogue 4-20mA current output which is isolated into 500Ω. The 4-20mA corresponds to the measured conductivity value, proportional to the full measuring range of the instrument, which makes it ideal for integration with a PLC, digital Chart Recorder or online Data Logger.  The isolated supply makes integration simple.

C3655 Inductive Toroidal Conductivity Controller Set-points and Relays

The C3655 uses a set-point and corresponding control relay to take charge of industrial processes. The relay offers On/Off control and is 2 amp non-inductive. The set-point can also make use of a user configurable delay timer which can be set from 0-40 seconds before calling for the relay to energise. This is ideal for use in control processes where the conductivity control can produce relay "chattering".

The set-point can be set anywhere between 0-100% of the scale of the C3655 giving complete control across the full measuring range.

C3655 & SI315 Features and Benefits

The SI315.1 and C3655 offer an excellent way of measuring and controlling many industrial applications.

The SI315 is manufactured in chemically resistant PVDF allowing it's immersion into processes using concentrated chemicals. With a measuring range of 0 - 200.0mS or 0 - 2000mS, this makes the SI315 & C3655 the perfect conductivity controller and cell combination for use in solution strength control applications.

While toroidal or inductive conductivity measuring devices offer many advantages, the main disadvantage is that they are limited in measuring clean water applications. For conductivity values lower than 2000µS we would recommend an electrolytic Insertion Conductivity Cell or an Electrolytic Dip Conductivity Cell.

When the conductivity value is in the upper ranges or becomes so high as to blind a traditional electrolytic cell, the SI315 is the perfect combination. As the toroidal windings allowing us to measure the conductive aren't in contact with the solution.  These are non-fouling, even in solution with very high conductivities which can risk coating traditional conductivity electrodes.

With the advantage of being non-fouling and the chemically resistant PVDF as the material of construction, the C3655 & SI315 are often found in solution strength for the control of acids in the surface coating sector.  The instruments are also to be found in detergent strength control for CIP applications in the food and beverage sector as well as for use in difficult to reach boiler and cooling water control applications, where a traditional conductivity cell with exposed electrodes can be difficult to reach for periodic maintenance and calibration.

As the SI315 and C3655 are simple to connect together, the controller is easy to operate with the toroidal conductivity cell, the C3655 is a no-nonsense way of measuring and controlling conductivity processes with an easy initial setup and minimal maintenance required.

C3655 Conductivity Control Specifications

  • Specifications


    Conductivity Controller

    Model No:- C3655

    Inductive / Toroidal / Electrodeless Conductivity Controller

    Conductivity Ranges:- 0 - 200.0mS to 0 - 2000mS

    Supported Cell Constants:- n/a

    Temp. Compensation:- 2% per °C from base 25°C

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

    Action:- On / Off with delay timer of 0-40 secs

    Current output:- 0 - 20/ 4 - 20mA isolated into 500Ω

    Zero:- ±15

    Slope:- ±20%

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

    Weight:- 265 grams DIN version

    Dimensions:- 108 x 58 x 100mm cutout

    Conductivity Cell

    Model Number:- SI315

    Inductive / Toroidal / Electrodeless Conductivity Cell

    Cell Constant:- N/A

    Measuring Range:- 0 - 200.00mS or 0 - 2000mS

    Materials of construction CellPVDF

    Max temperature:- 0-80°C

    Max pressure:- 3 Bar at 20°C

    Temperature Compensation:- Via Internal Temperature Measuring Device

    Connections:- Supplied with 3 Metres of connecting cable.

  • Features


    • C3655 Din Rail mounting controller for use in control panels or supplied for surface mounting or C3655W supplied in Wroof surface mounting enclosure.
    • Non-fouling SI315 toroidal or inductive electrodeless conductivity sensor. Perfect for use in processes which coat traditional conductivity cells where the electrodes are in contact with the solution.
    • Easy to setup, install and use
    • In built temperature compensation to provide accurate results even when temperature fluctuations in the solution can occur.
    • User configurable set-point and control relay with high or low operation, and on / off control with user configurable delay timer.
    • Isolated 4-20mA current output isolated into 500Ω, which is ideal for data-logging or connecting to a PLC.
  • Data Sheets

    Data Sheets

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