Question 8Electricity/Electronics - Assistant Engineer70% to pass
The AC winch hoist controller shown in the illustration has a burned out hoist contactor coil that must be replaced. Before replacing the coil, the cause for the burnout must be determined. Which of the following statements represents the possible cause? Illustrations EL-0102
AI Explanation
The correct answer is C.
The possible cause for the burnout of the hoist contactor coil is that accumulated dirt can prevent the proper seating of the armature to the magnet, even with a normal voltage applied to the coil (between 85% and 110% of the rated voltage). This condition can lead to excessive heating and burnout of the coil, as the armature may not be able to fully engage the magnet, causing the coil to work harder and overheat.
The other options are incorrect because: A) insufficient voltage will not cause a burnout, and B) excessive voltage is not the issue here. D) is incorrect because an air gap between the armature and magnet is not the problem - the issue is the accumulated dirt preventing proper seating.
Related Questions
#6 As part of a routine maintenance program for deck machinery motor controllers, what should be done? #7 If a spring-set electric solenoid-released brake on a winch fails to hold a load properly when the solenoid is de-energized, what must be done? #9 If deck machinery is expected to be idle for an extended period of time, what should be done? #10 An AC winch hoist controller such as shown in the illustration has welded contacts on the hoist contactor, and the contacts must be replaced. Before replacing the contacts, the cause for the welding of the contacts must be determined. Which of the following statements describes the possible causes? Illustration EL-0102 #11 Relative to the number of turns of a secondary winding of a step-up transformer, what will be the number of turns of a primary winding?