Question 309Electricity/Electronics - Assistant Engineer70% to pass
When you are making a high potential test (megger) on the motor coils of repaired electrical machinery to ground. What would a low resistance reading indicate?
AI Explanation
The correct answer is B) bad insulation.
A low resistance reading when conducting a high potential (megger) test on motor coils would indicate that the insulation between the coils and ground is compromised or defective. This is because good insulation should have a very high resistance to ground, and a low reading signifies a fault or breakdown in the insulation integrity.
The other answer choices are incorrect because:
A) A high slot discharge factor is not directly related to the insulation resistance measured during a megger test.
C) High insulation power factor is also not indicated by a low resistance reading, which points to bad insulation.
D) Good insulation would result in a high resistance reading, not a low one.
Related Questions
#307 Large machines undergoing a resistance insulation testing using a megohmmeter should be discharged to remove any accumulated electrostatic/capacitive charge stored. When should this discharge be performed? #308 When using the test set-up shown in figure "A" of the illustration, besides the motor windings and the motor feeder cable, what circuit components are actually being meggered? Illustration EL-0027 #310 Suppose it is desired to connect a dual voltage three phase squirrel-cage induction motor for low volts, but it is undetermined whether the nine-lead motor is internally configured for wye or delta configuration. Using an ohmmeter, the motor itself with leads disconnected, and the illustration as a guide, what statement is true? Illustration EL-0134 #311 Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor? #312 As shown in figure "A" of the ungrounded distribution system with possible ground faults shown in the illustration, under what conditions would an outage likely occur due to a ground fault causing a circuit breaker to trip? Illustration EL-0129