Appendix A: Ballast Test
Rapid Start Ballasts
Rapid start ballasts supply a controlled low voltage (filament voltage) which heats the lamp cathodes sufficiently for the starting voltage to initiate an arc. If the filament voltage is low, the lamps may not start.
The filament voltages for the most typically encountered rapid start ballasts are:
- F30T12/RS – 3.5 to 4 volts
- 800ma – 3.5 to 4.3 volts
- F40T12/RS – 3.5 to 4 volts
- 1500ma – 3.5 to 4.3 volts
Cathode Cut-Out (Hybrid) Rapid Start Ballasts
To perform the tests outlined above on (2) lamp hybrid ballasts, one lamp must be in place while the other sockets are tested. Remove only one lamp at a time.
Electronic Ballasts for Rapid Start Lamps
Because of the special operating characteristics of many electronic ballasts, such as high-frequency operation, parallel circuitry and instant starting, field testing can be difficult and procedures varied. Eliminate other possible causes and replace the ballast if necessary.
A circuit tester can be used to determine whether the ballast is functional.
Instant Start (Slimline) Ballast
Because of wiring variations between ballast manufacturers, and the availability of Series and Lead-Lag ballast circuits, miswiring is the most frequently encountered cause of Slimline system problems. Check the manufacturer’s catalog or the ballast label for the correct wiring diagram.
Typical variations in Slimline wiring.
Check the ballast label!
(click on charts above to enlarge)
CHECKING THE STARTING VOLTAGE OF A SLIMLINE BALLAST SHOULD ONLY BE PERFORMED BY A LICENSED ELECTRICIAN.
The starting voltage is measured across the primary and secondary leads to the sockets, using a high resistance voltmeter with a range of zero to 1000 volts.
Minimum Starting Voltage
- F72T12 – 475 volts
- F96T12 – 565 volts
For other applications and additional information, consult Universal Lighting Technologies’ Technical Engineering Service Department.
The open circuit voltage of a Slimline ballast is often sufficient to strike an arc even if only one lamp cathode is operational. This will overheat the ballast and adversely affect its service life. End-of-life or burned-out lamps left in the fixture will also place abnormal stress on the Slimline ballast. Universal ballasts incorporate internal protection which minimizes the adverse effects of lamp problems on the ballast.
End of Service Life
A ballast will perform its designed function for many thousands of hours until insulation on the coil windings break down, or an internal component, such as the capacitor, fails. Following the troubleshooting charts will determine the root cause of a problem and help avoid unnecessary and costly ballast replacement.
- OTHER SIGNS OF END-OF-LIFE BALLASTS INCLUDE:
- Excessive noise
- Leaking of potting compound
- Nuisance trip-outs (See Chart 4 – "Cycling")