Referring to 2.4.0 Table 2A, what is the probable cause if the symptom is "Failure of equipment to start with contactor closed"?

• A. One contact not closing
• B. Coil burned out
• C. Open fuse
• D. Shorted contact

Answer: (A)

When the coil is energized and the contactor shows as closed, power should flow to the motor through the main contacts. If the motor still won’t start, the issue is in the power path after the coil has pulled in. The most likely cause is that one of the main contacts is not closing properly. A contact can wear or burn and fail to make a full, clean connection, leaving part of the circuit effectively open and preventing the motor from starting even though the contactor is pressed in.

The other possibilities don’t fit the observed condition as well: a coil burn-out would stop the contactor from pulling in in the first place, so you wouldn’t see a closed contact. An open fuse would interrupt power before the motor circuit, again not consistent with a closed contact. A shorted contact would typically cause a fuse or breaker to trip or create a different fault symptom, not just a failure to start with the contactor closed.