All the units use the input voltage through a step up transformer to obtain the high AC voltages. In case of DC output the AC is rectified through a suitable rectifier capable of withstanding the high voltages. Some units use a combination of AC and DC that is switched to deliver AC or DC or both. In the case of VLF equipment a pseudo sine wave is produced through a number of switches and resistors.

The outputs are current limited and the unit automatically trips when a set limit is reached. When this occurs the cable is discharged and made safe through a built in discharge resistor. In case the circuit layout does not allow (in case of split units) the automatic discharge of the cable, a suitable manual discharge resistor is supplied The units are portable and simple to operate.