Ballasts: 1 of 21
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An electric discharge lamp is hard to start, but once the discharge starts it is a short-circuit. It is out of control like a runaway train going downhill.
A ballast is required
to put the brakes on the
electric discharge and to bring it under control.
A ballast performs three functions:
(1) It (often) acts as a transformer to step up the voltage
(2) It starts the lamp, usually by putting out a high voltage or an electric pulse
(3) Once the discharge has started, it regulates or limits the current flowing through the lamp to the appropriate value.