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UV Lamp & UV Ballast Electrical Requirements
UV Lamp & UV Ballast Electrical Requirements
Line voltage alone is generally insufficient for generating an arc inside the UV lamp; requiring a step-up transformer to develop the higher voltages required. Because mercury vapor UV lamps are negative resistance devices, they normally require a ballast to prevent them from drawing excessive amounts of current and ultimately destroying themselves.
There are two primary types of reactive ballasts used to operate mercury vapor UV lamps, inductive and capacitive. With inductive ballasts, the UV lamp is connected directly to the output of the ballast. These types of UV ballasts have two benefits. First, the reactance of the inductor effectively limits the power available to the UV lamp with only minimal power losses. Secondly, the voltage spike produced by the inductor when power is first applied is often used in some circuits to strike the arc in the UV lamp. The disadvantage of the inductive-reactance UV ballast is that current is shifted out of phase with the voltage producing a lower power factor.
Capacitive reactance UV ballasts overcome this problem by the use of capacitors connected in series with the UV lamps. These capacitors maintain a constant voltage output to the UV lamp even when the input voltage varies and is the more efficient of the two.
It’s critical that UV ballasts have to be correctly matched to the electrical requirements of the UV lamps.
There are two primary types of reactive ballasts used to operate mercury vapor UV lamps, inductive and capacitive. With inductive ballasts, the UV lamp is connected directly to the output of the ballast. These types of UV ballasts have two benefits. First, the reactance of the inductor effectively limits the power available to the UV lamp with only minimal power losses. Secondly, the voltage spike produced by the inductor when power is first applied is often used in some circuits to strike the arc in the UV lamp. The disadvantage of the inductive-reactance UV ballast is that current is shifted out of phase with the voltage producing a lower power factor.
Capacitive reactance UV ballasts overcome this problem by the use of capacitors connected in series with the UV lamps. These capacitors maintain a constant voltage output to the UV lamp even when the input voltage varies and is the more efficient of the two.
It’s critical that UV ballasts have to be correctly matched to the electrical requirements of the UV lamps.
