A single core and coil ballast can be used when the input voltage to a fixture meets the starting and operating voltage requirements of an HID lamp. In this situation, the reactor ballast performs only the current-limiting functions since the voltage necessary to initiate the ignitor pulses, and start and sustain the lamp comes directly from the input voltage to the fixture. The reactor ballast is electrically in series with the lamp. There is no capacitor involved with the operation of the lamp. Because of that, the lamp current crest factor is desirably low, in the 1.4 to 1.5 range.
Without a capacitor, the reactor ballasts are inherently normal power factor devices (50%). Where necessary, to reduce the current draw during lamp operation, a capacitor may be utilized across the input line to provide high power factor (90%) operation, but the addition of the capacitor will not affect how the ballast operates the lamp.
Magnetic ballasts, capacitors are needed to improve (input) power factor. As a result, the number of lamps that can be operated on a circuit nearly doubles. In large installations, power factor correction is also required to avoid power quality problems and utility penalties. Capacitors are integral components of CWA and regulated lag circuits; they will not operate without capacitors. Both oil-filled (wet) and dry-film capacitor technologies are commonly used with ballasts. A means to discharge capacitors after power is turned off is a safety requirement.
both oil-filled and dry film capacitors for the HID and sign ballast lighting markets.Constructed with film designed to withstand the rigors of the application, these units are built to operate up to 105ºC.
HID lighting film capacitors are built with a ±3% tolerance on capacitance, and are designed to operate for a minimum of 60,000 hours. Sign ballast capacitors are constructed with film/foil technology and have tolerances based on application requirements.
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