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