Magnetic Ballast Technology
All gaseous discharge light sources (metal halide, fluorescent, mercury, high and low pressure sodium) require an electrical power supply known as a ballast for proper operation. The ballast transforms the electrical power provided by the utility to a form that is suitable for operation of the lamp. It provides specialized circuitry to facilitate ignition and maintains proper operating conditions by limiting the electrical current supplied to the lamp during steady-state operation.
A ballast is fundamentally comprised of a transformer, a capacitor, and in some cases an ignitor (pulse-start metal halide, ceramic metal halide and high pressure sodium). The transformer utilizes magnetic induction to alter the characteristics of the electrical power source through application of one, two or three copper coils on a core (or "stack") of electrical grade steel laminations. This gives rise to the commonly used term "core-and-coil" ballast. These magnetic devices have become more highly refined over the years, but it is core-and-coil ballast technology that has powered all types of HID light sources since their inception. The capacitor is used to correct the normally poor power factor of the transformer. And where applicable, the ignitor generates a momentary, high voltage pulse (>2500V) to ignite the lamp.
Magnetic ballasts come in a variety of basic designs with varying performance characteristics (efficiency, power factor correction, ability to absorb line voltage variations). The most widely used design is known as the Constant Wattage Autotransformer (CWA). Others versions include Constant Wattage (CW), Reactor (R), High Reactance Autotransformer (HX) and Regulated Lag (REG LAG). These may be available in different physical configurations (packages) and with options such as multi-tap capability or sound reduction.
A key consideration in ballast selection relates to the thermal environment that the product will be subjected to. Applications that expose ballasts to ambient temperatures in excess of 40°C (104°F) threaten to shorten component life and may require a special ballast designed for high ambient temperature operation.
All SES magnetic ballasts are high quality CWA products that…
- comply with North American and international safety, performance and design standards, including U.L., CSA and ANSI
- provide high power factor correction
- have a 4kV ignitor specifically for pulse-start metal halide lamps
- are 100% factory tested after assembly
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Electronic Ballast
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