Diagnostics

How to check a single-phase motor capacitor

How to check a single-phase motor capacitor

The capacitor is the weak point of a single-phase motor. It is because of this that the engine most often hums, but does not start. Let's look at how to check the capacitor and when to change it.

Why do you need a capacitor

The capacitor creates a phase shift in the starting winding, without which a single-phase motor cannot move. There are starting (short-term) and working (permanent) capacitors.

Symptoms of malfunction

  • The engine hums, but does not start.
  • Weak start, the engine takes a long time to accelerate.
  • Bloating of the capacitor body.
  • Traces of electrolyte leaks.

How check

MethodWhat shows
Capacity meterComparison with the rating on the case
External inspectionBloating, smudges
Multimeter (mode capacitance)Performance

Important:Before testing, the capacitor must be discharged - it can store a charge. Work in compliance with safety precautions. If the capacitance is noticeably lower than the nominal value or the capacitor is swollen, it is replaced.

What to do after replacement

If after replacing the capacitor the engine still does not start, the reason is deeper - a break in the starting winding or jamming. Then you need diagnostics, and if the winding is damaged - rewind.

A single-phase motor does not start in Tashkent? Elektromotors engineers will check the capacitor and windings - contact us.

Need specialist help?

Contact Elektromotors engineers — we will help diagnose and repair your electric motor.

+998 94 680 15 04 Contact us
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