EPC 50 - Diagnosis & Rectification of Circuits Faults

Question 1

Who is responsible for ensuring that commissioning has been carried out on an installation?

Answer 1

The electrical contractor.

Question 2

What is the general distinction between commissioning and testing an installation?

Answer 2

Commissioning involves ensuring correct operation. Testing involves using instruments to ensure that mandatory and specified technical requirements have been met before power is applied.

Question 3

List FOUR aspects which must be considered when commissioning a new factory installation, after all regulatory requirements have been satisfied?

Answer 3

Voltage.  Phase rotations. 
Loading up.  Correct functioning. 
RCD checks.  Voltage drop.
Isolation checks, Motor directions. 
Safety interlocks. Emergency systems checks.

Question 4

What effect does ‘phase rotation’ have on the operation of a three phase induction motor?

Answer 4

Phase rotation determines the direction of rotation of the three phase motor.

Question 5

How should disconnected conductors be treated after they have been temporarily removed from an electrical device so that the device can be taken away for testing?

Answer 5

Label the conductors.
Tape all bare conductors.
Leave cable tidy and secure.

Question 6

What is meant by the term ‘decommissioning’ an electrical installation?

Answer 6

Systematically isolating and removing electrical devices in a planned sequence so that the installation, or part thereof, can be taken out of service and left in a safe and tidy condition with documentation in the main switchboard updated.