When Safety Instrumented Systems (SIS) are applied within a chemical facility you can’t always plan for every loop condition. Sometimes input cards are active and sometimes passive. Field transmitters are sometimes line powered (four-wire) which usually have active outputs, and sometimes they are passive (two-wire). Moreover, is the field transmitter HART capable or not?
When those unplanned situations exist, you can turn to the Functional Safety Series SST Signal Isolator. The SST is an exida approved four-wire SIL 2 capable isolator that provides superior noise rejection and full three-way isolation with HART pass-through capability. Additionally, the input to the SST can be wired in the field as an active input (applies power to the two-wire field transmitter) or passive input. The output of the SST can be ordered as active or passive. Another very important feature of the SST that is very critical for an SIS, is that the output of the SST will track the input all the way to 0mA when it fails; as opposed to most other isolators that simply go to 4mA – which is always difficult to ascertain between a failure of the input or just 0% scale.
- exida certified to SIL 2
- HART pass-through capability
- Output tracks to 0mA on failed input