Universal Lighting Technologies

Appendix F: Capacitor Test

Checking the Capacitor

1. Disconnect the capacitor.
2. Discharge the capacitor.
3. Use an ohmmeter on the highest scale.
4. If meter reads low resistance initially and increases, the capacitor is GOOD.
5. If meter reads low resistance initially and does not change, it is SHORTED and must be replaced.
6. If meter reads high resistance initially and does not change, it is OPEN and must be replaced.

Be sure to check for and correct abnormal conditions such as high ambient temperature, incompatibility, etc. -which may have caused or contributed to capacitor failure, or caused the capacitor’s internal protector to activate.

Faulty Capacitor

Capacitor Condition Ballast Type Result
Shorted High Reactance High line current. May open circuit breaker or burn out the primary coil of the ballast. Capacitor's internal protector may function, resulting in open capacitor and normal power factor operation.

Shorted CWA Metal Halide and Mercury High lamp current. May open circuit breaker or burn out the primary coil of the ballast. May shorten lamp life.

Shorted CWA HPS Low lamp current. Low light output. No ballast damage.

Shorted CWA Dual (Parallel) Capacitor (one shorted) See above results, depending on ballast type used.

Open High Reactance Lose power factor correction. High line current. May open circuit breaker. May burn out the primary coil of the ballast.

Open CWA Single Capacitor Lamp will not light.

Open CWA Dual (Parallel) Capacitor (one open) Low lamp current. Low light output.

Open CWA Dual Capacitor (both open) Lamp will not light.