Question 8Electricity & Electronics - Assistant Engineer

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.