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FAQ of the Day

Question:
When is it necessary to design a safety system to satisfy the requirements of EN 954-1 Category 4?

Answer:
Category 4 safety requirements are usually associated with extremely high-risk applications. Consequently the safety system needed to satisfy these conditions can be quite complex and costly.

Since general machine design practice respects classic safety hierarchy, most extremely high-risk hazards - that is:

• those which the operator cannot avoid
• those is which the operator is exposed frequently or continuously, and
• those which could result in serious injury, amputation or death

are designed-out during machine development or are guarded against (if they cannot be designed-out).

Consequently for most applications it is generally not necessary to incur the cost/complexity of Category 4 safety system design. Many low-risk situations can be satisfied by safety systems that meet the requirements of Category B, 1 or 2 as defined by EN 954-1.

In most higher-risk situations, a suitable safety system (and one which meets ANSI's requirement for "control reliability") can be achieved with a system designated to meet the Category 3 requirements of EN 954-1.

When needed, Category 4 requirements can be satisfied by proper selection from SCHMERSAL's wide range of CE-compliant safety interlocks and related safety circuit monitors.

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