J
The design of a process Safety Instrumented System (SIS) might contain one or more hard-wired switches in order to manually actuate shutdown devices. The switches might be wired as inputs to the SIS logic solver (relay, PLC, TMR, etc.) or in parallel with it. Frequently the switches utilize 24V DC normally closed contacts.
As the trend toward consolidation of control rooms progresses, the manual switches may have to be located relatively long distances (1 km or more) from the logic solver or shutdown devices.
What are the control community's thoughts on different ways to implement manual switches without long cable runs, while still maintaining the reliability needed for an SIS?
As the trend toward consolidation of control rooms progresses, the manual switches may have to be located relatively long distances (1 km or more) from the logic solver or shutdown devices.
What are the control community's thoughts on different ways to implement manual switches without long cable runs, while still maintaining the reliability needed for an SIS?