Question 124Electricity/Electronics - 1st Asst/Chief70% to pass
A digital multimeter is set up as shown in the illustration to evaluate the single-circuit stator windings of a squirrel cage induction three-phase motor. The following readings are taken: From T1 to T2 reads 1.6 ohms. From T2 to T3 reads "OL" ohms. From T3 to T1 as shown reads "OL" ohms. What condition is indicated? Illustration EL-0219
AI Explanation
The correct answer is A) Phase A (associated with T1) is open-circuited.
The reasoning is as follows:
- The reading of 1.6 ohms between T1 and T2 indicates that the winding associated with Phase B (T2) is intact.
- The "OL" (open-loop) readings between T2-T3 and T3-T1 indicate that the windings associated with Phase C (T3) and Phase A (T1) are open-circuited.
- This means that Phase A (associated with T1) is the winding that is open-circuited, which is the correct answer (A).
The other options are incorrect because:
B) is incorrect as Phase C (associated with T3) is not the open-circuited winding.
C) and D) are incorrect as they do not correctly identify the open-circuited phase.
Related Questions
#122 Which of the following statements represents the reading display of a hand-cranked megohmmeter when testing a capacitor start motor start capacitor in good condition that has been properly discharged prior to the test? #123 As shown in figure "A" of the illustration, with a digital multimeter set up as an ohmmeter, what set of readings would be consistent with an open in phase "C" of the single circuit, wye-connected stator windings as shown? Illustration EL-0201 #125 What would happen if the centrifugal switch or relay, for cutting out the starting winding of a split-phase induction motor, failed to open while the motor was in operation? #126 Which of the following problems will most likely occur if the starting winding of a split- phase induction motor failed to cutout once the motor approached operating speed? #127 When testing the rotor of a synchronous motor for short circuits, a low voltage source is applied across the rotor coils through the collector rings. What would be the indication of a short- circuited coil?