Series CA  Instrumentation class

Isolated high accuracy conditioners

General description

CA series conditioners provide electrical (galvanic) isolation between the sensor and measuring system up to 1500 V. They have a very high accuracy, linearity and durability, and there is a large number of different models. Common to this type of conditioner is that it has an analog input channel that accepts signals from all types of commercial sensors.

Sensor signal is filtered, amplified, isolated, linearised, filtered again and converted to a level suitable for connection to the system for data acquisition, industrial PC, PLC or any other measurement system.


  • Isolation 1500 Vrms (4.000 V, 1 minute)
  • Accuracy 0.03% of full range
  • Linearity better than 0.01% of full range
  • 80 dB NMR for 50Hz
  • 160 dB CMR
  • Triple isolation: input-output-power supply
  • Power supply: 19 V to 30 V DC
  • Output: current or voltage, unipolar or bipolar
  • Input protected minimum 250 Vrms continuous
  • Waranty 7 and service 10 years


  • Industrial and laboratory appications
  • Protection from ground loop
  • Protection from dangerous voltages
  • Protection of electronic equipment from static electricity, transients and discharge
  • Reduction of RF i EMI noise from measurement signal
  • Increases reliability of equipment and time before failure (MTBF)


Conditioners types

The following table lists the types of conditioners from the CA series that are available. They are further divided into smaller groups with specific specifics on the following pages of the description.

Series Function
CA-30 Voltage input conditioners
CA-32 Current input conditioners
CA-33 Effective (RMS) voltage and current conditioners
CA-34 Linearised RTD with 2 or 3 connections
CA-36 Potentiometer input conditioner
CA-37 Conditioners for thermocouples with cold junction compensation
CA-38 Bridge measurement conditioners
CA-42 Conditioner for current loop sensor input
CA-43 Universal conditioners with DC excitation
CA-47 Thermocouple conditioners with cold junction compensation and linearisation

Technical details

Analogue isolation conditioners of the Series CA significantly raise the accuracy of measurement, reliability and professionalism in the applications of data acquisition systems, in measurement and process management. This group of conditioners was developed after many years of consideration of the requirements and needs of the users. Characteristics that are constantly improving are accuracy, linearity, repeatability and protection against accidental voltage connections, transients and other hazardous events. The CA series at this time is produced in variations of over 400 models.

Depending on the Family, the conditioners have a typical linearity of 0.01% of full range, small hysteresis and excellent repeatability. High temperature stability does not require calibration. However, on the front of the module there are two multi-turn potentiometers that allow the user to change the set values ​​to the output level that is required for some application. This correction is possible within a range of typically 3% full scale.

Thermocouple Conditioners Families CA-37 and CA-47 have a cold-end compensation of the thermocouple of 0.5 C. Unlike the CA-37 Series, the CA-47 Series has a degree of linearization of the signal from a thermocouple that hardware-implemented the so-called segment approximation. This hardware add-in frees the user from writing the linearization code of the thermocouple in its acquisition system or PLC.
The difference between the non-linearity of the sensor and the linearization performed by the CA module was called "mismatch approximation". The term "Conformity" is often in use.
Most models of this group of conditioners have a generally accepted frequency band of 3 Hz. Exceptions are conditioners with a frequency range of 100 Hz and 1 KHz for measuring bridges with current inputs and models for measuring the effective voltage and current. For standard models, the output noise level is below 200 μVrms. For fast measurements, ED offers models with a broadband amplifier with a frequency range of 10 kHz and a linearity equivalent to 14 bit A / D converters.

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

"Common-mode" is between 105 and 160 dB. The filter is the fifth order and suppresses 50 Hz with 80 dB (10,000 times). The CA module has built-in electronic protection circuits at the input and output, which allow these modules to be operational in an hostile electrical environment. Protective circuitry protects the input to at least 250 VAC. The input and output are protected from excessive events as defined by ANSI / IEEE C37.90.1-1989.

The modules are powered by a DC 24 V voltage or a voltage that can be between 19 V to 30 V DC. The CA series is designed to be "hot-swappable", that is, modules can be plugged into the system or disconnected from the system without having to switch off the power supply beforehand. On the front of each module there is a LE diode that indicates the presence of a supply voltage. Typical consumption is between 25 and 50 mA, depending on whether the module has a voltage or current output.

The conditioners have excellent stability in time and do not require additional calibration or any maintenance. The warranty period is 7 years and the service period is 10 years. It is delivered with a user manual in Serbian language and with a calibration list.

Power supplies for CA conditioners

For the power supply of a smaller number of conditioners, up to 20, the CS-24-30 power supply of 30W (picture on the left) is recommended, and for more, CS-24-90 of 90W should be used, which can power up to three times more conditioners. Both models can use the T-BUS connectors directly, without wiring to power the conditioners that are on the same, or with the extension cable on different DIN rails in a closed environment. This option raises reliability, significantly reduces the time of replacing the conditioner and enables the switching on and off of the conditioner when the bus T-bus is powered up.

Both power supplies work in a wide voltage range from 160V to 265V AC. If the user does not want to use this type of power supply, he can also use other power supplies, but in this case the power must be wired between conditioners

The conditioners should be specifically specified for the environment with increased humidity. In this case, they are protected by a composite lacquer that protects the components from moisture and corrosion. This feature significantly extends the life of this product and in terms of long-term measurement accuracy. The prepared conditioner can be used in many aggressive environments, for example on ships at the seaside, in conditions of aggressive vapours, at the water supply facilities, etc. 


The power supply input is designed to provide protection against inverse polarity and against transients as defined by ANSI / IEEE C37.90.1-1989 document.

The CA Series modules have dimensions: Height 105 mm; width 22.5 mm, and depth of 114 mm. All modules are in accordance with DIN EN 50022 35 mm standard for a DIN rail of 19 "width. Operating temperature is -40 C to +85 C, for accuracy by specification is -25 to +80 C. The relative humidity is up to 95% without condensation.

If none of the offered conditioners fully complies with your application, a conditioner can be produced on request using the user specification. For this option, call ED, +381/11/308-50-30.

CA dimensions in millimetres.



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