PLC PLC Safety & Functional Safety

Question 1

Which international standard defines functional safety requirements for safety-instrumented systems in the process industry?

Accepted Answer

IEC 61511

Answer

IEC 61511 is the functional safety standard specifically for safety-instrumented systems in the process industry.

Question 2

What does SIL stand for in the context of safety PLCs?

Accepted Answer

Safety Integrity Level

Answer

SIL stands for Safety Integrity Level, a measure of the reliability and risk reduction provided by a safety function.

Question 3

A Safety PLC operating at SIL 2 typically requires which architecture to meet hardware fault tolerance requirements?

Accepted Answer

1oo2 (one-out-of-two) redundancy

Answer

SIL 2 commonly requires a 1oo2 (1-out-of-2) hardware architecture to achieve the necessary hardware fault tolerance.

Question 4

What is the primary purpose of a Safety Instrumented Function (SIF)?

Accepted Answer

To bring a process to a safe state when a hazardous condition is detected

Answer

A Safety Instrumented Function (SIF) is designed to take a process to a defined safe state upon detection of a hazardous condition.

Question 5

Which term describes the probability that a safety function fails to respond when a dangerous condition occurs?

Accepted Answer

Probability of Failure on Demand (PFD)

Answer

PFD (Probability of Failure on Demand) quantifies the likelihood that a safety function will not operate correctly when called upon.

PLC - Programmable Logic Controller Certification Practice Test