Capacitor capacitance measurement – how to check a motor capacitor

Why we measure capacitance

In single-phase motors, the capacitor directly affects startup and torque.

What the measurement indicates

If the actual capacitance has dropped significantly compared to the nominal value, the capacitor may be worn out.

Symptoms

• The motor hums.
• It has difficulty starting.
• It overheats.

Caution

The capacitor must be safely discharged before any inspection.