The following procedures are to be adopted for determining the types of cable faults whether it is a phase to phase fault, a phase to ground fault or an open circuit fault-
a) To test ground fault or short circuit fault a meggar of 500 or 1000 volts is used. Before starting the testing procedures it is to be ensured that the far end of the cable is open and free from earth connection. In case of testing ground fault the ‘L’ terminal of the meggar is touched with each conductor of the cable by rotation and the ‘E’ terminal is permanently connected with a good earth lead. After rotation the meggar handle when the meggar indicates zero reading it means the respective conductor is earthed.
b) In case of testing short circuit fault the two terminals of the meggar are touched with two conductors of the cable. After rotating the meggar handle when the meggar indicates zero reading it means the two conductors are short circuited.
The same procedures are adopted for other conductors.
c) To test open circuit fault the three conductors are short circuited at one end. The two meggar terminals are touched with two conductors of the cables at a time. After rotating meggar handle when the meggar indicates zero reading it means the conductors are continuous, but when the meggar indicates infinity reading it reading it means there is an open circuit in the conductor.
