CA Series Instrumentation class

High accuracy isolated signal conditioners

General description

CA Series signal conditioners provide electrical (galvanic) isolation between the sensor and the measurement system up to 1500V. They have very high accuracy, linearity and durability, and there are many different models available. Common to this type of signal conditioners is that they have one analog input that receives signals from all commercial sensor types, and one analog output for standard data acquisition systems.

The signal from the sensor is filtered, amplified, isolated, linearized, re-filtered and converted to an output voltage or current level suitable for connection to a data acquisition system, Industrial PC, PLC, or other measuring system.

Electronic Design has made signal conditioners with bipolar output! Output ranges of 5mA, 10mA and 20mA are available. It is also possible to make a current output at the request of the user. Bipolar current output facilitates process control and allows bidirectional control for small signals without additional components.


  • Galvanic isolation 1500 Vrms (4.000 V, 1 min.)
  • Accuracy 0.03%
  • Linearity better then 0.01%
  • 80 dB NMR for 50Hz
  • 160 dB CMR
  • Tripple isolation: input - output - power supply
  • Power supply from 19 V to 30 V DC
  • Output: current or voltage
  • Continuous input protection al least 250 Vrms
  • BUS connector for power over DIN rail
  • 7 year warranty period and 10 year service


  • Industrial and laboratory applications
  • Measurment of electrical and sensor signals
  • Ground loop protection
  • Protection against life-threatening voltages
  • Protection of electronic equipment against electric potentials, transients and discharges
  • Reduction of RF and EMI noise from measuring signals
  • Increase of system reliability and MTBF

SIgnal conditioner types

The following table lists the available CA series conditioner families. They are further subdivided into smaller groups with specific features on the following pages of the description.

Family  Function 
CA-30  Voltage input signal conditioners
CA-32  Current input signal coditioners
CA-33  True RMS voltage or current input signal conditioners
CA-34  Linearised RTD with 2 or 3 wires
CA-36  Potentiometer input signal conditioners
CA-37  Signal conditioners for thermocouples with CJC
CA-38  Measurment bridge signal conditioners
CA-42  Two-wire current loop input signal conditioners
CA-43  Universal condicioners with DC excitation
CA-47  Signal conditioners for thermocouples with CJC and linearisation

Technical details

The CA Series Analog Insulation Conditioners significantly improve measurement accuracy, reliability and professionalism in data acquisition systems, measurement and process management applications. This group of signal conditioners was developed after many years of consideration of user requirements and needs. Features that are constantly improving are accuracy, linearity, repeatability and protection against accidental voltage connections, transients and other hazardous events. The CA series is currently being produced in variations of over 400 models.

Depending on the Family, conditioners have a typical linearity of 0.01%, low hysteresis and excellent repeatability. High temperature stability implies they do not require calibration. However, there are two multi-turn potentiometers on the front of the module that allow the user to recalibrate the setpoints to the output level required for some other application. This correction is possible in the range up to typically 3% of span.

Thermocouple conditioners CA-37 and CA-47 have a 0.5 C cold junction compensation. Unlike the CA-37 Series, the CA-47 Series also has a linearization of the signal from a thermocouple that is implemented in hardware. This hardware add-on frees the user to "write" the thermocouple linearization code in their acquisition system or PLC.

Most modules in this group of signal conditioners have a generally accepted frequency range of 3 Hz. The exceptions are conditioners with current input having a frequency range of 100 Hz and 1 KHz for measurment bridges modules and models for measuring effective voltage and current. For fast measurements, ED offers models with the isolation amplifier using a frequency range of 10 kHz and linearity corresponding to 14 bit A / D converters.

Each CA conditioner has isolation between the input and output sides to a voltage level of 1500 Vrms and 4 kV for 1 minute. All modules in this series have triple isolation that places an isolation barrier between the input and output stage of the conditioner and the power supply stage. The power supply is galvanically isolated from both the input and output side of the conditioner.

Common-mode rejection is between 105 and 160 dB. The filter is fifth order and suppresses 50 Hz at 80 dB (10,000 times). The CA module series has electronic input and output protection circuits, which allow these modules to be operational in a hostile electrical environment. Protective circuits protect the input up to 250 VAC, and the power input from reverse polarity. Input and output are protected against excess events as defined by ANSI / IEEE C37.90.1-1989.

The modules are powered by 24 V DC or between 19 V and 30 V DC. The CA series is designed to be "hot-swappable", that is, modules can be plugged into or disconnected from the system without first switching off the power supply. An LED is mounted on the front of each module indicating the presence of a supply voltage. Typical power consumption is between 25 and 50 mA depending on whether the module has a voltage or current output.

The signal conditioners have excellent temperature stability and do not require additional calibrations or any maintenance. The warranty period is 7 years and the service life is 10 years. It comes with a user guide in English and a calibration list.

Power supply and T-BUS connector

For the power supply of a smaller number of conditioners up to 20, a CS-24-48 that delivers 48W is recommended (picture on the left), and for greater number of conditioners a CS-24-90 of 90W should be used. Both models can, via the T-BUS connector be connected, directly, without wiring to power the conditioners on the same, or with the extension cable, on different DIN rails in a closed environment. This option raises reliability, greatly reduces the time of replacement of the conditioner and allows the conditioner to be connected or disconnected while the T-BUS is powered up.

Both power supplies work in a wide voltage range: CS-24-90 from 160V to 265V AC, while smaller, CS-24-48 can operate as much as 85V to 265V. If users do not want to use this type of power supply, they can also use other power supplies, but in this case, the power supply must be wired from one conditioner to the other by cables.

Picture on the left: Power supply CS-24-48 for conditioners with T-BUS connector


The printed circuit board of the conditioner on request can be protected with special lacquer which protects electronic components from moisture, corrosion and other types of contamination, which can significantly extend the life of this product and in terms of long-term measurement accuracy. When conditioner is prepared in this way it can be applied in many aggressive environments. For example: on ships or on the seashore, in conditions of aggressive vapors, and other places with high humidity, etc...

The CA Series modules have dimensions: height 105 mm; width 22.5 mm, and depth 114 mm. Up to 18 modules can be fitted to one 19" DIN rail. All modules are DIN EN 50022 35 mm standard compatible. Operating temperature is -40 C to + 85 C, and -25 to 80 C for accuracy spec. Relative humidity up to 95% non-condensing.

If none of the signal conditioners offered satisfies your application completely, conditioner according to the user specification can be produced upon request. For this option, please call Electronic Design on: + 381 / 11 / 308-50-30.



CA series dimensions in milimeters [mm] 



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