SIL Functional Safety Principles & Standards 5

Question 1

Which international standard provides guidance specifically for the application of functional safety in the machinery sector?

Accepted Answer

IEC 62061

Answer

IEC 62061 is the IEC 61508-derived standard for safety-related control systems in the machinery sector, defining SILCL requirements.

Question 2

A functional safety plan (FSP) required by IEC 61511 must document which of the following?

Accepted Answer

The functional safety activities, responsibilities, and resources for all lifecycle phases

Answer

The FSP defines the overall approach to managing functional safety, covering activities, responsibilities, resources, and schedules across all lifecycle phases.

Question 3

When applying the risk graph method for SIL determination, which parameter accounts for the ability of people to avoid the hazard after it has been initiated?

Accepted Answer

Probability of avoiding the hazard parameter (P)

Answer

The avoidance parameter (P) in the risk graph reflects whether people can avoid the hazard after initiation, such as through warning or escape routes.

Question 4

Under IEC 61508, what does 'hardware fault tolerance (HFT)' of 1 mean?

Accepted Answer

The system requires redundancy such that one fault does not cause loss of the safety function

Answer

HFT = 1 means the subsystem can tolerate one dangerous hardware fault without losing its ability to perform the safety function, typically requiring redundancy.

Question 5

What is the significance of the 'ALARP' (As Low As Reasonably Practicable) principle in functional safety risk assessment?

Accepted Answer

It requires that residual risk be reduced further if the cost of doing so is not grossly disproportionate to the benefit gained

Answer

ALARP requires demonstrating that residual risk has been reduced to the lowest level practicable, with further reduction only waived if costs are grossly disproportionate to safety benefit.

(SIL) Safety Integrity Level Certified Practice Test

(SIL) Safety Integrity Level Certified Practice Test

SIL Functional Safety Principles & Standards 5