When operating fluorescent lamps with inductive control gear, the power factor (referred to as cos φ for sinusoidal quantities) is a mere 0.3 to 0.5. To prevent elevated loads on the supply network due to reactive power, construction regulations e.g. of German energy providers require the use of compensation for discharge lamp operation where more than 250 W of system performance (lamp power plus control gear power loss) are connected per outer conductor. The aim is a power factor over 0.9.
Reactive power compensation
Compensation can be implemented individually per luminaire or via one central compensation installation.
For individual compensation, the method of parallel compensation has become established throughout Europe. Serial compensation was used in the former West German states due to specific technical framework conditions until the year 2000. From the year 2000, parallel compensation has been implemented in Germany, as everywhere in Europe.
Serial compensation led, among other issues, to an increased power consumption of the entire circuit which is why its application has been banned since the control gear directive’s first restriction level’s entry into force (see chapter 188.8.131.52) in 2002. When operating retrofit LED lamps in place of intended fluorescent lamps in parallel-compensated luminaires, capacitive phase shifts between current and voltage can occur and generate a power factor λ ≤ 0.25 (see also chapter 184.108.40.206). This leads to increased levels of reactive current, which in turn often causes up to twice the current load on the circuit compared to the original fluorescent lamp (see also chapter 220.127.116.11, "LED (Light-Emitting Diodes)").