Leakage-field transformers - uv-technik international ltd. uv lamps, uv units and uv equipment

1) Without load, i.e. if the lamp has not been started, it outputs its complete open-circuit voltage (also called ignition voltage) which is designed sufficiently high for the connected lamp to start immediately.

2) When the lamp has started, the output voltage drops to the operating-voltage level of the lamp due to the flowing current. As soon as the lamp has reached its operating temperature, the current adjusts itself to what is needed for the required lamp power.

As the characteristics of the lamps can be different depending on the type and also on the required power, a leakage-field transformer must be tuned exactly to these values and built accordingly. Dependence on the mains voltage and the mains frequency must also be taken into account.

Versions for all mains voltages (AC) and frequencies found worldwide are feasible, also with tappings for different outputs. Due to the design principle, it is not possible to switch power levels during lamp operation, the lamp would extinguish during the switching. Separate so-called partial-load chokes which can be switched using contactors are required for switching during operation.

As leakage-field transformers are inductive components, they generate an undesired phase shift between mains voltage and mains current which must be compensated by compensation capacitors.

cos phi transformer = approx. 0.5 … 0.55
cos phi target = approx. 0.9 due to the capacitors