1. Resistance Measurement: Verifying Winding Functionality
Use a multimeter in resistance mode to measure the resistance between the three motor leads:
Normal Rule: Minimum resistance + Second largest resistance = Maximum resistance. For example, readings of 80Ω, 123Ω, and 203Ω meet the standard, indicating the windings are intact.
Abnormal Judgment: If the resistance between any two leads is 0Ω, it indicates a short circuit in the windings; if it is ∞ (infinity), it indicates an open circuit, and the motor is damaged.
2. Insulation Performance Test: Preventing Leakage Risk
Use a multimeter in 10kΩ range or a megohmmeter to measure the resistance between any lead and the motor's metal casing:
The normal value should be infinity (0Ω) or >0.5 megohms, indicating good insulation.
If the reading is less than 0.5 megohms, it indicates a potential leakage risk, and the motor must be stopped and replaced.
3. Mechanical and Operating Status Inspection
Manual Rotation: After power is off, gently rotate the motor shaft. It should rotate smoothly without any jamming. If it feels heavy or makes abnormal noises, it may be due to bearing wear or rotor rubbing.
Power-On Test: After powering on, observe whether there is difficulty starting, low speed, or a "humming" sound. These may be signs of capacitor aging or partial winding burnout.
Visual Inspection: Check if the coil is blackened, and whether the casing has cracks or corrosion. Blackening usually indicates overheating and burnout, rendering it unrepairable.
⚠️ Safety Precautions: Always disconnect the power before any test. Discharge the capacitor before measuring it to avoid electric shock. If the fault cannot be determined, it is recommended to have it handled by a professional.
