Capacitors, Ignitors and Starters
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 .
Oil-filled capacitors are encased in metal and are filled with a dielectric fluid. They can be operated upto 100 degrees C however 90 degrees C is the common rating. Most of the oil-filled capacitors manufactured by GE and others have two 1/4” spade terminal lugs on the top of the capacitor for the connection point. When replacing a new capacitor please make sure to not cut the terminal leads attached to the wires coming from the ballast. These terminals will need to be reused to attach to the new capacitor. These capacitors are extremely reliable and can come in voltage ratings upto 525V.
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.
High Intensity Discharge(HID) ignitors provide a short, high voltage or pulse to breakdown the gas between the electrodes of a particular HID lamp. Ignitors are used in High Pressure Sodium(HPS) systems and certain Metal Halide(MH) pulse start systems. The voltage given off by any one ignitor may vary from 0 to 5000KV with variations as well in the period of time the pulse is given. If the ignitor is timed to late or is not functioning properly the lamp will not start.
Starters are common name for “glow tube starter”, these are the small cylindrical aluminum or plastic vessels that are used in fluorescent lighting systems. Inside the plastic or aluminum vessel is a small glass tube that is filled with a gas usually neon and a radio frequency interference suppression capacitor. At the base of the vessel are two twist and lock pins. Starters must be matched to the appropriate wattage of lamp that they are starting for reliable light and operation. Inside the glow tube there is a switch, this switch is normally open and when power is turned on the glow discharge tube heats the bimetal contact. After it is heated the bimetal contact is closed and provide the current needed to the fluorescent lamp that is in-line.