Question 308Electricity/Electronics - Assistant Engineer70% to pass
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

AI Explanation
The correct answer is B) the power circuit of the starter up to the load side of the main contacts.
When using the test setup shown in figure "A" of the illustration EL-0027, the megger is connected to the motor windings and the motor feeder cable. This means the circuit being meggered includes the power circuit of the starter up to the load side of the main contacts, but not the control circuits or components beyond the main contacts.
The other options are incorrect because they either include too much of the circuit (D), or exclude components that should be included (A and C).
Related Questions
#306 What is a useful instrument for checking 3 phase AC motor performance by measuring possible unbalanced currents? #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? #309 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? #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?