During a growler test, what indicates a short exists between an armature segment?

• A. The bearing hum
• B. The test blade vibrates and chatters
• C. The field coil glows
• D. The stator windings become magnetic

Answer: (B)

A growler test looks for shorted turns in the armature by using a magnetic field and a small metal test blade. When a shorted turn is present, current is induced in that turn and the local flux interacts with the growler’s field, causing a fluctuating magnetic pull. That varying force makes the test blade vibrate and chatter as you move it across the armature. If there are no shorted turns, the blade stays quiet because there’s no such localized, alternating attraction. The other options don’t indicate a shorted turn: bearing hum is a bearing issue, the field coil glowing points to overheating or excessive current in the field, and merely the stator windings becoming magnetic is a normal effect of energizing the machine, not a diagnostic sign of a shorted armature turn.