Dry-Film capacitors are internally different from the oil-filled capacitor. They do not use a dielectric fluid. These capacitors are only available typically in voltages upto 400V however strides are being made to make them in higher voltages. They are available in temperature ratings starting at 100 degrees C and have become a more attractive alternative to oil-filled capacitors. They have a higher ambient temperature rating, no exposed parts, much more compact size, inherent self clearing component prevents failing in a “shorted” mode and they are packaged in plastic housings so they do not need special clearances or grounding.
With HID lamps operating on lag and HX type ballasts, capacitors are needed to increase (input) power factor. When doing so the number of lamps that can be used or operated on a particular circuit can nearly double. In fact in instances where a large number of lamps and ballasts are used, power factor correction is also needed to avoid problems with power quality and penalties from utility companies. Capacitors are a main component of a CWA and regulated lag circuit system. These systems will not operate without capacitors in line. Oil-filled (wet) and dry-film capacitors are commonly used with all types of ballasts technologies. Note: As a safety requirement, there must be a means to discharge capacitors after power is turned off .