SACA Safety Systems and Functional Safety 3

Question 1

What is the primary function of a safety light curtain (light screen) in machine guarding?

Accepted Answer

To detect the presence of a person or object in a hazard zone and initiate a machine stop

Answer

To illuminate the hazardous work area for quality inspection

Answer

To measure the speed of moving machine components

Answer

To communicate machine status to a remote operator panel

Question 2

What is the primary purpose of Lockout/Tagout (LOTO) procedures under OSHA 29 CFR 1910.147?

Accepted Answer

To control hazardous energy and protect workers during equipment servicing or maintenance

Answer

To prevent unauthorized personnel from entering a production area

Answer

To document machine downtime intervals for maintenance scheduling

Answer

To synchronize production schedules across different work shifts

Question 3

According to ISO 13849-1, Performance Level 'd' (PL d) corresponds to a probability of dangerous failure per hour (PFH) in which range?

Accepted Answer

≥10⁻⁷ to <10⁻⁶

Answer

≥10⁻⁵ to <10⁻⁴

Answer

≥10⁻⁶ to <10⁻⁵

Answer

≥10⁻⁸ to <10⁻⁷

Question 4

What is the key distinction between an active and a passive safety system?

Accepted Answer

Active systems respond dynamically to detected hazards; passive systems provide protection without requiring activation

Answer

Active systems require external power; passive systems use only stored mechanical energy

Answer

Active systems are software-based; passive systems are purely hardware-based

Answer

Active systems require human intervention; passive systems operate automatically at all times

Question 5

A two-hand control device on a machine press is designed primarily to:

Accepted Answer

Ensure both hands of the operator are away from the hazard zone before and during the machine cycle

Answer

Allow two operators to jointly control the machine at the same time

Answer

Provide redundant control signals to improve system reliability

Answer

Allow faster cycle times by reducing operator interaction delays

Question 6

Under ISO 13849-1, what does Category 3 architecture require that distinguishes it from Category 2?

Accepted Answer

A dual-channel redundant architecture where a single fault does not cause loss of the safety function

Answer

A single channel with periodic diagnostic testing

Answer

Three independent voting channels with a 2oo3 logic

Answer

No specific architecture beyond meeting the required PL

Question 7

In a machine safety application, a safety relay module is primarily used to:

Accepted Answer

Monitor safety input devices and provide safe switching outputs with internal fault detection

Answer

Program safety logic using ladder diagram or function block language

Answer

Replace the machine's standard PLC for all control functions

Answer

Increase the processing speed of the machine control loop