If a short exists between armature segments during a growler test, what observable effect occurs when a metal blade is held over the armature?

If a short exists between armature segments during a growler test, what observable effect occurs when a metal blade is held over the armature?

• A. The blade will spin rapidly
• B. The blade will vibrate and chatter
• C. The blade will melt
• D. The blade will glow

Answer: (B)

During a growler test, the armature is magnetized and a ferrous blade is swept over its surface to sense weak spots. If there is a short between armature segments, the current finds a low-resistance path and concentrates the magnetic flux in that area. The resulting localized, pulsating magnetic attraction pulls on the blade and then releases it as the field strength fluctuates, causing the blade to vibrate and chatter. If there were no short, the flux wouldn’t create a strong, uneven pull, so the blade would stay relatively still. The other outcomes—rapid spinning, melting, or glowing—would require far more energy or heat than this test provides.

During a growler test, the armature is magnetized and a ferrous blade is swept over its surface to sense weak spots. If there is a short between armature segments, the current finds a low-resistance path and concentrates the magnetic flux in that area. The resulting localized, pulsating magnetic attraction pulls on the blade and then releases it as the field strength fluctuates, causing the blade to vibrate and chatter. If there were no short, the flux wouldn’t create a strong, uneven pull, so the blade would stay relatively still. The other outcomes—rapid spinning, melting, or glowing—would require far more energy or heat than this test provides.