The portable Sonel VLF test sets are used for testing of medium voltage cables with extruded insulation (XLPE-, EPR-insulation) in acc. to DIN VDE 0276/620, CENELEC HD 620 S1 or IEEE 400.
VLF is the very best and most effective method for insulation testing of medium voltage power cables with extruded (plastic) insulation. Using 0.1 Hz VLF test voltage, weak spots in XLPE, PE and also oil impregnated paper insulated cables are quickly brought to a controlled breakdown without causing additional damage or aging to the remaining cable insulation.
Cable sheath test with direct voltage is possible as well.