Answer to Question #183575 in Electrical Engineering for John

Question

PLCs are very useful devices that are used for a wide variety of applications such as controlling the operation of the automatic roller door to the entrance of KPL Foods warehouse in assignment 1. The equipment poses a number of health and safety issues which must be taken into consideration to prevent harm.

a) Describe some of the health and safety issues which should be considered.

 

b) Identify at least 4 relevant Health and Safety legislations which should be observed when working with programmable controlled equipment.

Answer 1

Answers to the question.

A.

- In a PLC system, a stop signal is provided by a switch.

- If there is a failure, the output revert to a fail-safe mode so that no harm come to anyone.

- Emergency stop buttons and safety guard switches are hardwired and do not depend on the PLC software for implementation.

B.

- A fuse of circuit breaker should be used to protect against cover current on the supply wiring. Also each input/output could each have their own fuse for protection.

- Care must be taken to avoid placing low-voltage signal wires and communication cable next to AC cables as could lead to potential interference.

- You should supply a switch which can terminate the power from all PLC equipment used if need.

- Some kind of anti surge protection should also be fitted to stop any lighting surges from damaging any PLC equipment.