Terminology HF-ballast

Warm start  

Correctly optimised ignition of fluorescent lamps, where the cathodes at the ends of the lamp are pre-heated to the right temperature, allowing controlled discharging to take place. This creates the best conditions for maximising the fluorescent lamps life span.

Cold start 

Igniting fluorescent lamps without pre-heating the cathodes, causes the cathodes’ emissions-material to be consumed quicker. The advantage this offers is smaller and less expensive electronic control gear. These are suited only for industrial premises, and places, where fluorescent lamps are not switched on and off more than once or twice a day.

Nominal voltage  

The operating voltage is stated on the luminaire label. Normally, HF-ballasts work without problems within ±10 % fluctuation of the nominal voltage. Check the voltage is correct. Too high or too low can damage the electronics. Most HF-ballasts also work with direct voltage. Please contact us for this type of operation.

Harmonics are distortions of the mains voltage’s waveform caused by non-linear loads on the mains. Harmonics give rise to distorted currents, high magnetic fields and interference to sensitive electronic apparatus. Computers, frequency converters, standard compensated luminaires are large harmonic producers. The guideline value for computers is approximately 80 % THD, standard luminaires approximately  20 % THD and HF-ballasts about 10 %. Low quality HF-ballasts can be large producers of harmonics.


Total Harmonic Distortion.

Operating frequency 

is the discharge current’s frequency in the fluorescent lamp. In luminaires with magnetic ballasts this equals the mains frequency 50 Hz. HF-ballasts convert the mains frequency to approximately 25–50 kHz. The luminaire’s efficiency is also improved by approximate 10 % in this case. As the operating frequency also modulates light, this can cause problems with infrared detectors used in alarm systems and lighting control. The problem can however be avoided through the right choice of HF-ballast.


Also called electrode. The cathodes at each end of the fluorescent lamp are made of tungsten filaments, coated with beryllium oxide. When heated, electrons are released which maintain the lamp’s discharging current. Incorrect temperature on the cathodes shortens the lamp’s life span. This occurs primarily with dimming when the fluorescent lamp output drops, which can seriously shorten the lamp’s life span. This is avoided by using high quality HF-ballasts.