UV Lamp Ballasts

Mercury vapor ballasts are designed to drive tubular medium pressure ultraviolet lamps. There are two types of mercury vapor lamps. The most common is the medium pressure lamp with no metal additives. This lamp is available in arc lengths of 1 to 120 inches. The other type of lamp is a metal-additive-mercury-vapor lamp. The additives used in the lamp create changes in the lamps spectral output enhancing different portions of the ultraviolet spectrum. The ballast initiates and controls the arc in mercury and metal additive curing lamp. This is accomplished by providing an instantaneous high voltage to strike the elements within a mercury vapor lamp, creating a plasma that, once initiated, is sustained by the ballast. Total wattages up to 50 kilowatts can be designed. Our constant wattage ballast consists of a transformer, capacitors and igniter.
The advantage of a constant-wattage ballast is that it allows for wide variations in input voltage to affect output wattage by only a few percent. These ranges can be customized to meet your applications requirements. Typical designs have an output variation of only +- 3% with an input voltage varying over a range of -15% to +10%. Constant wattage is accomplished by a resonant tank circuit in which the lamp winding is in controlled magnetic saturation with the AC capacitors, such that voltage swings on the input side have a very small impact on lamp current. An interesting feature is that these current-limiting capacitors can be switched (see schematic) in and out of the circuit to provide various lamp power levels.