How to improve the power factor of gas discharge lamps

Power factor of the ballast of gas discharge lamps

In addition to incandescent lamps, gas-discharge lamps are used for lighting. They are connected to the network through a control mechanism (ballast)... The ballast circuit uses inductive ballast resistances or filament transformers that reduce the power factor of these lamps by 0.5 — 0.8. Therefore, energy consumption increases by 1.7 — 2 times.

To reduce the reactive power consumed by the lamps, capacitor installations with a voltage of 380 V are used in lighting networks with alternating current with a frequency of 50 Hz. The capacitors are connected directly to each lamp or on the group lines of the power shields for a group of lamps.

Required capacitor power to increase the power factor from cos phi to cos phi2, determined by the formula Q = P (tan phi1 — tg phi2), where P is the installed power of the DRL lamps, including losses in the ballast, kW; tg phi1 is the tangent of the phase angle corresponding to cos phi1 to compensation; tg phi2 is the tangent of the phase angle after compensation to the set value cos phi2.

250, 500, 750 and 1000 W DRL type lamps apply group compensation due to the lack of special capacitors for individual reactive power compensation. The electrical industry produces static capacitors of a certain powerfor example 18 and 36 kvar.

To increase the power factor from 0.57 to 0.95, it is necessary to install 1.1 kvar capacitors for each kilowatt of active power of the lamp.

Since in the group lighting network, the maximum current of the machine breaker must be no more than 50 A, the maximum power of the lighting group with DRL lamps can be no more than 24 kW.

Three-phase capacitors are connected to the three-phase lines of the group lighting network after the group breaker installed on the group boards and designed to protect the capacitors and lighting control.

To improve the power factor in lighting networks with lamps of the DRL type, three-phase capacitors with a voltage of 380 V for 18 or 36 kvar are installed. Depending on the type of capacitor bank, it accommodates from one to four capacitors with discharge resistors.

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