The IS-SLT3 range provides protection to most three-wire signalling schemes. The units are shunt connected to the terminals and hence do not interrupt or interfere with the signal. Therefore, the IS-SLT3 range can be adapted to most instruments. Applications may include instruments which are field powered with a single wire control signal.

In addition, the IS-SLT4-RTD is specifically designed for resistive temperature detectors (RTD) such as PT100 types. This unit caters for all two, three and four wire RTD systems.