HID BALLAST TERMINOLOGY
Today HID lighting users demand long lamp life, high lumen output, quick starting, improved lumen maintenance, and most of all, energy efficiency. To satisfy the needs of yesterday, today, and the future, STANDARD has developed one of the most complete and comprehensive line of HID ballast products available. |
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WHAT IS A BALLAST?
HID lamps require ballasts to perform the following functions:
- Provide starting voltage and, in some cases, a high voltage pulse through the use of an ignitor. Ballasts must provide a specific minimum starting voltage to ignite the lamp. Pulse Start metal halide and high pressure sodium lamps; require an additional high voltage pulse (typically between 2.5 to 6.0 kV).
- Regulate lamp current and power. The ballast current is set to a level that provides proper power to the lamp. In addition, the ballast regulates the lamp current through the range of typical line voltage variations, thus keeping the lamp power relatively stable, maximizing lamp life and performance.
- Provide the appropriate sustaining voltage and current wave shape to achieve the published rated lamp life. The ballast provides sufficient voltage to sustain the lamp as it ages. Lamp voltage typically increases as the lamp ages, and a well engineered ballast prevents the lamp from dropping out or cycling during the lamp’s rated life. The ballast must also deliver a suitable current wave form to the lamp as specified by ANSI (American National Standards Institute).
EFFICACY
A metric used to compare light output to energy consumption. Efficacy is measured in lumens per watt. Efficacy is similar to efficiency, but is expressed in dissimilar units. For example, if a 100 watt source produces 9000 lumens, then the efficacy is 90 lumens per watt.
HIGH PRESSURE SODIUM (HPS)
A high intensity discharge lamp type that uses sodium under high pressure as the primary light producing element. |
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METAL HALIDE (MH)
A high intensity discharge lamp type that uses mercury and several halide additives as light producing elements. |
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METAL HALIDE PULSE START
A metal halide lamp which offers higher light output, longer lamp life, more stable colour rendering, and quicker startup.
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OPEN CIRCUIT VOLTAGE (OCV)
The voltage applied across the output terminals of a ballast when no load is connected. This is the voltage applied across a lamp circuit to start a lamp. After starting, the voltage rapidly decreases and stabilizes at the operating voltage. When testing OCV it is recommended that a true RMS be used to insure accuracy.
POWER FACTOR (PF)
PF is a measure on how efficiently a ballast can transform voltage and current provided by the power line into watts of usable power to the lamp. A power factor of 1.00 would mean power is being used perfectly.
- Low power factor (LPF): Essentially, an uncorrected ballast power factor of less than 0.90.
- Normal power factor (NPF): A ballast/lamp combination in which no components (e.g., capacitors) have been added to correct the power factor, making it normal (essentially low, typically 0.50 or 50%).
- High power factor (HPF): A ballast with a 0.9 or higher rated power factor, which is achieved by using a capacitor.
REGULATION
The ability of a ballast to hold constant (or nearly constant) the output watts (light output) during fluctuations in the voltage feeding of the ballast. Normally specified as +/- percent change in output compared to +/- percent change in input.
CORE AND COIL
The basic and most common ballast is the open core and coil which is most often used as a component within a lighting fixture. The core and coil also forms the main component of the other HID product types listed below.
The core and coil type consists of either one, two or three copper coils depending on the circuit type. These coils are on what is called a core (or “stack”) of electrical grade steel lamination. The coils are assembled to core sections which are then surface-welded together using typically automatic welders to insure consistency.
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