There’re three general faults in electric integrity, one by one to go through and we will understand the basic concept of electric installation.
Open circuit Fault
- Due to the broken of conductor (Wire broken)
Open circuit will cause the 3-phase Motor stop (Over load relay will trip the motor if the current is over the normal ). Some case the load will be increase on the remain 2-phase and burn out the motor.
Protection: Do the Megger check between one point to the earth ( The wire earthed at one end already ). The result is infinity mean Open circuit.
Short circuit Fault
- Due to contact between two conductor but no load applied (Current leak from hot to Neutral)
Short circuit will cause high current passing through the winding, other loads…and burn out. (Over load relay will trip the equipment if the current is over the normal ).
Protection: Do the Megger check between hot port and neutral port (Equipment unplug) , The result is less than infinity mean Short circuit some where or there’s connect between two termination Hot and Neutral.
- Due to the break in insulation and conductor (phase) touch to the ground or hull steel (allow current flow to the ground and back to the grounded winding generator, excessive current will trip the generator.)
- Different with Earth leakage (that the broken conduct touch to the casing of equipment, if no Grounding –> Electric shock)
Protection: Do the Megger check between terminal and earth. The result is less than infinity mean of electric leakage.
Additional knowledge about the basic housing electric.