Determining if a jewelry miniature motor is overloaded can be done by combining observation of its physical behavior during operation with the use of testing tools. Here are the specific methods:
1. Observe Typical Overload Symptoms
Abnormal Temperature Increase: Gently touch the motor casing. If it is noticeably hot (above 60℃, hotter than lukewarm water), it may be due to excessive current causing coil overheating.
Speed Decrease or Instability: Under load, a significant decrease in motor speed, "breathing" fluctuations, or even stopping are important signs of overload.
Abnormal Noise and Vibration: A dull humming sound, a sharp friction sound, or violent shaking indicates uneven internal stress or mechanical jamming.
Unusual Odor: A burnt smell of insulating varnish or grease indicates that the windings or bearings have been damaged due to overheating.
2. Use Tools to Test Key Parameters
Measure Current: Use a clamp meter to measure the operating current. If it consistently exceeds the rated current value marked on the motor nameplate, it is overloaded.
Check Three-Phase Balance (Applicable to Multi-Phase Micro Motors): A three-phase current deviation exceeding 10% may indicate a hidden overload caused by a missing phase or incorrect wiring.
Insulation Resistance Test: Use a 500V megohmmeter to measure the winding-to-ground insulation resistance. If it is below 0.5MΩ, it indicates moisture or aging, which can easily lead to leakage overload.
3. Troubleshoot Common Causes
Excessive Mechanical Load: Such as a stuck transmission mechanism, excessively tight gear meshing, or an overloaded rotary table, resulting in insufficient power for the motor.
Power Supply Issues: When the voltage is too low (<10% of the rated voltage), the motor will automatically increase the current to maintain output power, causing overload.
Incorrect Wiring: Incorrect star-delta connection or a loose ground connection can cause leakage current, leading to abnormal heating and circuit breaker tripping.
Poor Environmental Heat Dissipation: Dust blocking the motor's air ducts or installation in a confined space reduces heat dissipation efficiency and exacerbates temperature rise.
