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SIL3 Design
SIL3 instrument and wiring to PLC

Hi,

Can anyone share a sample real case SIL3 Instrument and its wiring to a SIL3 system. what are the main things to take care of?

What is basic architecture?

By W.L. Mostia on 7 March, 2018 - 11:20 pm

There are not many SIL3 instrument around and most will be logic solvers. This is because a SIL 3 instrument generally require a hardware fault tolerance of 1 or an approval (by IEC 61508) to SIL 3.

There are many SIL 2 sensors that can be utilized in a SIL 3 system in a redundant configuration (e.g. 1oo2, 2oo3, etc.). If you are a manufacturer, you need to refer to IEC 61508. If you are a user, then refer to ANSI/ISA 84.00.01/IEC 61511. Here is a link to a web site that discusses redundant configurations.

http://www.smar.com/en/technical-article/sis-safety-instrumented-systems-a-practical-view-part-5


William (Bill) L. Mostia, Jr. PE
ISA Fellow, FS Eng. (TUV Rheinland)
WLM Engineering Co.