Response time requirements for the SIS system

The response time requirements for the SIS, to bring the process to a safe state, shall be stated. [ IEC 61511-1 ]. Parameters that affect the response time are:

Process related

• time constants in the process itself
• dead time in process response

Control system (electrical)

• time delay in control system
• the sampling time of the controller

Other (mechanical)

• inertia
• friction
• wear