Question

a fluorescent lamp taking 100w at 0.75 p.f lagging from a 240v, 50Hz supply is to be eorrected to unity p.f. determine the value of the correcting appasatus required​

Answer 1

Answer:

The power Pn (watts) indicated on the tube of a fluorescent lamp does not include the power dissipated in the ballast.

The current is given by: {\displaystyle {\mbox{Ia}}={\frac {{\mbox{P}}_{\mbox{ballast}}+{\mbox{Pn}}}{{\mbox{UCos}}\varphi }}}

Where U = the voltage applied to the lamp, complete with its related equipment.

If no power-loss value is indicated for the ballast, a figure of 25% of Pn may be used.

Standard tubular fluorescent lamps

With (unless otherwise indicated):

cos φ = 0.6 with no power factor (PF) correction[1] capacitor

cos φ = 0.86 with PF correction[1] (single or twin tubes)

cos φ = 0.96 for electronic ballast.

If no power-loss value is indicated for the ballast, a figure of 25% of Pn may be used.

Figure A6 gives these values for different arrangements of ballast.

Fig. A6 – Current demands and power consumption of commonly-dimensioned fluorescent lighting tubes (at 230 V-50 Hz)

Arrangement of lamps, starters and ballastsTube Power (W)[a]Current (A) at 230 VTube Length (cm)Magnetic BallastElectronic BallastWithout PF correction capacitorWith PF correction capacitorSingle tube180.200.140.1060360.330.230.18120580.500.360.28150Twin tubes2 x 180.280.18602 x 360.460.351202 x 580.720.52150

Jump up^ Power in watts marked on tube

Compact fluorescent lamps

Compact fluorescent lamps have the same characteristics of economy and long life as classical tubes. They are commonly used in public places which are permanently illuminated (for example: corridors, hallways, bars, etc.) and can be mounted in situations otherwise illuminated by incandescent lamps (see Fig. A7).

Fig. A7 – Current demands and power consumption of compact fluorescent lamps (at 230 V - 50 Hz)

Type of lampLamp power (W)Current at 230 V (A)Separated ballast lamp100.080180.110260.150Integrated ballast