Question 10Electricity/Electronics - Assistant Engineer70% to pass
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
AI Explanation
The correct answer is D.
The welding of contacts in an AC winch hoist controller can be caused by low applied voltage to the operating coil (less than 85% of rated voltage) or by weak springs. Low voltage can cause excessive current flow through the contacts, leading to overheating and welding. Weak springs may not provide enough force to separate the contacts, allowing them to weld together.
The other options are incorrect because:
A) Excessively strong springs would not cause welding of the contacts.
B) Excessively high voltage (more than 110% of rated voltage) can also cause welding, but this is not the only potential cause.
C) Weak springs, not strong springs, can contribute to contact welding.
Related Questions
#8 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 #9 If deck machinery is expected to be idle for an extended period of time, what should be done? #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? #12 When a transformer is used to step down voltage, what statement is true? #13 Which of the following statements is true concerning step-down transformer operation?