VLF is not new. The reason it has not been widely used for more than 4-5 years is because only in the last 5 –10 years has it been determined that DC voltage testing damages solid dielectric cable and is an ineffective means of determining insulation quality. Also, the original and current European designed VLF units were and are large, heavy, expensive, and some do not produce the desired sine wave output.

It was not until High Voltage, Inc. developed the first line of truly portable, inexpensive, and sine wave producing units that it became feasible and economical to VLF test in the field. Hundreds of HVI VLF units have now been shipped worldwide over the last 5 years, with thousands to follow.