Check continuity across each phase. An infinite resistance reading signifies a broken wire within the internal coils or connections. Short Circuit Tests
When Robert Rosenberg—a former vocational instructor in New York City—first published his guide, his goal was to provide an intensely practical reference manual for workers with minimal electrical backgrounds. The resulting text quickly became legendary for its heavy reliance on illustrative drawings (more than 900 in the classic editions) and step-by-step repair methodologies. electric motor repair robert rosenberg pdf updated
Use a digital multimeter to measure resistance across the motor windings. The resistance across all phases of a three-phase motor should be nearly identical. Check continuity across each phase
: Practical guides for lap windings, concentric windings, and identifying leads for dual-voltage motors. and identifying leads for dual-voltage motors.