Question 257Electricity & Electronics - Assistant Engineer

The correct answer is D) loose connections or low contact pressure. Loose connections or low contact pressure in an operating motor controller can cause excessive heat or burning of the contacts. This is because poor electrical connections increase the resistance in the circuit, leading to higher current flow and localized heating at the contact points. This excessive heat can then cause the contacts to burn or fuse together, further exacerbating the issue. The other answer choices are not the primary causes of this problem. Low motor starting torque (A) and a burned-out operating coil (B) would not directly lead to excessive heat or burning contacts. High ambient temperature (C) may contribute to the problem, but it is not the root cause.