Safe Signal Circuit for SIL 3 with a Single Transmitter

Nov. 30, 2011
Four new transmitter power supplies reportedly reduce costs by enabling users to construct an intrinsically safe signal circuit for SIL 3 with a single transmitter.

Single-channel KCD2-STC-Ex.1ES and KFD2-STC4-Ex1.ES transmitter power supplies are assembled to the 35 mm DIN mounting rail with power rail. HiC2025ES and HiD2025ES transmitter power supplies are mounted on prewired termination boards. These modules provide internal diagnostics information using a single failure signal, and are designed for intrinsically safe applications up to SIL 3 according to EN61508.

Historically, this was only possible using two separate inputs, both of which had to be monitored for redundancy. Internal diagnostic functions are also signaled via a single output and red LED. Prescribed test intervals can be extended for SIL 2 applications as well.