Rapid Start Ballast


What are they?

The majority of fluorescent fixtures with more than two lamps are typically known as rapid start. This style of ballasts do not contain a starter and instead leverage a minimal amount of electrical current circulating to filaments continuously, or for some models, during the start-up period which also usually leverages a capacitor or other methods to initiate the lamp and ionize the gas which helps negate any resistance of gas to a flow of current.

Advance RC-2S85-TP Rapid Start Ballast Label

With ionizing the gas, the rapid start ballast obtains a low current flow of electricity moving through the lamp which causes the ballast to glow lightly. This helps start heating the gas throughout the lamp evenly which further illuminates the light and adds ionization and further lowers the gas resistance. At the same time, the ballast is directing current to the filaments throughout the lamp which also helps the starting process.

All of these activities quickly lower the resistance of the gas and help the lamp leverage the current while it brightens, and this is why rapid start ballasts light up so rapidly, albeit in stages of brightness but eventually delivering full light.

Design and Technical Specifications

Most rapid start fluorescent feature two, three, four T12 (1.5″ diameter) lamps with one ballast managing a limit of two lamps each. When there are more than two lamps, it is common that two ballasts are employed.

Rapid start ballasts are designed with a independent set of windings that transmit lower voltages – approximately 3.5 volts to the electrodes for a second before the lamp ignites. Rapid start ballasts are normally wired in series so if one lamp fails, all remaining lamps in the circuit cease to operate.

Because rapid-start ballasts are grounded, there is typically no actual wire connecting the ballast and reflector – in place of this, contact is made through metal parts of the fixture requiring. To help with the starting operation, contact between the ballast and metal surface is required about the entire length of the lamps, and of course for safe operation, grounding properly is required.

The initial voltage is typically less than that of an instant ballast which will normally use a voltage between 405-550 volts for F32T8 lamps.

With these ballasts, the initial voltage powers an electrical arc inside the lamp and will continue to warm the electrode despite the lamp turning on which creates power drain of between one and half through two watts per lamp.

Switch Cycles

Lamps paired with rapid start ballasts are normally rated to manage 15,000 to 20,000 power cycles.

Programmed Rapid Start Ballast

These ballasts have bee designed for use in occupancy switches and are rated higher than traditional rapid start ballasts with 30,000 rapid starts. Programmed rapid start ballasts will most often be set to warp the lamp’s cathodoes to 1,202°F or 650°C temperatures with glow being often non-existent before voltage is transferred to the lamp.

Like traditional rapid start ballasts, they are typically wired in a series, but some do have series-parallel lamp operation for lamp units three and four for redundancy so that other lamps can remain operable in case a lamp ceases to work.

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