Analog signal converter CW

galvanically-isolated

They convert electrical signals generated by sensors measuring physical quantities such as: temperature (thermocouples and PT100 resistance temperature detectors), frequency (proximity sensors, contacts, photocells), current (current transformers, Hall-effect sensors), resistance (potentiometers), voltage, pressure, level, etc., into standardized electrical signals, adapting them to the inputs/outputs of PLCs, DCSs, and industrial PCs (control systems).

Alternatively, they convert a given analog signal into a different one, adapting it to the control system’s inputs/outputs, or they allow the disturbance-free long-distance transmission of the signal by means of galvanic isolation .

Long-Distance Signal Transmission

Voltage signals can be transmitted over a maximum distance of 10–20 m; beyond this range they lose reliability and become highly sensitive to induced and ground disturbances. For this reason, in order to transmit a voltage signal over distances greater than 20 m, it is necessary to convert it into a current signal and provide galvanic isolation .

Current signals can be transmitted over distances exceeding 300 m and are less sensitive to induced disturbances. To transmit a current signal over long distances, galvanic isolation is required.

Galvanic Isolation of the Signal (Signal Isolation):

It electrically isolates and separates the sensor circuit from the control circuit and from the power supply circuit; therefore, each circuit operates with reference to its own zero potential which, being isolated from the other circuits, cannot be altered by the potential differences that are always present between different earth references .

It isolates and separates the different ground potentials between power supply, control system, and sensors/actuators.

It allows signal transmission without errors or disturbances and with greater reliability.

The higher the isolation rating (in kV), the greater the transmission safety in the presence of ground potentials, electromagnetic disturbances, and transients (lightning strikes, discharges, etc.)

Galvanic isolation is required when:

the distance between the control system and the sensor/actuator is greater than 20 m

the ground or reference potentials are different

ground potentials are high, or may become high in the event of discharges or earth leakage currents

electromagnetic interference is present

signal cables are installed in conduits together with power cables .

Series and Parallel Connection of Analog Converters

To obtain signal redundancy or simply to duplicate a signal, it is possible to connect the input of multiple converters to a single sensor.

In the case of current signals, the converter inputs must be connected in series .

In the case of voltage signals, the converter inputs must be connected in parallel

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