Which of the following is a symptom of a miswired control transformer in a motor start/stop circuit?

• A. Control transformer miswired
• B. Phase B fuse bad
• C. Motor coil short
• D. Wrong line voltage supply

Answer: (A)

In a motor start/stop circuit, the control transformer provides the low-voltage power for the control devices that operate the start/stop circuit. When the transformer is wired correctly, energizing the start pushbutton should properly energize the contactor coil and stopping should de-energize it. If the transformer is miswired, the control circuit can’t receive or apply the correct voltage to the intended terminals, so the control action behaves incorrectly or won’t operate at all. That specific wiring fault is what you’d identify as the symptom—the control transformer itself is miswired and causing the faulty control behavior.

The other issues point to different problems: a bad Phase B fuse indicates a power supply fault in one phase, not a wiring error in the control transformer; a motor coil short is a motor winding fault; and an incorrect line voltage supply affects the motor and overall power but isn’t a symptom of miswiring the control transformer.