A ballast that ensures the operation of the lamp at the desired power is required for using a UVH lamp. Combinations of chokes and a starter can be used for lamps operating at a power of up to 5 kW. In the power range of 5 kW up to approximately 8 kW, combinations of an autotransformer and chokes are used while leakage-field transformers are preferred from a power level of 8 kW upwards. The currently most powerful lamp provides 60 kW. Ballasts can be designed for single-level or for multi-level operation. Continuously variable variants are also available without any problems in all power ranges. Alternatively, continuously variable electronic ballasts can be used in the power ranges from 600 W to 40 kW and with a lamp length of up to 300 cm, in special cases also somewhat longer.
With conventional ballasts, stand-by operation at 35 – 40% of the maximum power output is possible if it is required by the respective process. If electronic ballasts are used, significantly lower standby power levels down to approx. 10% can be realised. Operation in stand-by mode almost always requires a reduction of the lamp cooling.