CAS CAS Automation Specialist Safety & Standards 2

Question 1

What is the definition of Probability of Failure on Demand (PFD) in a safety system?

Accepted Answer

The average probability that a safety function fails to respond when a demand occurs

Answer

The frequency at which a safety function activates unnecessarily

Answer

The percentage of time a system is offline for maintenance

Answer

The rate of spurious trips per year

Question 2

Which safety architecture uses redundancy where all channels must agree before a protective action is taken?

Accepted Answer

2oo2 (2-out-of-2)

Answer

1oo1 (1-out-of-1)

Answer

1oo2 (1-out-of-2)

Answer

2oo3 (2-out-of-3)

Question 3

In NFPA 70E, arc flash boundaries are established to protect workers from which specific hazard?

Accepted Answer

Thermal energy from an electrical arc

Answer

Chemical exposure

Answer

High-pressure hydraulic release

Answer

Radio-frequency interference

Question 4

What does the term 'proof test interval' mean in the context of safety instrumented systems?

Accepted Answer

The periodic interval at which a safety function is tested to detect dangerous undetected failures

Answer

The time between scheduled software updates

Answer

The maximum allowed response time of a safety sensor

Answer

The interval between operator certification renewals

Question 5

Which standard specifically addresses cybersecurity for industrial automation and control systems (IACS)?

Accepted Answer

ISA/IEC 62443

Answer

IEC 61508

Answer

NFPA 70E

Answer

IEC 61131-3

Question 6

In a risk matrix used during PHA, which two dimensions are typically evaluated?

Accepted Answer

Probability of occurrence and severity of consequence

Answer

Cost and schedule

Answer

Operator skill level and equipment age

Answer

Detection time and repair time