High-frequency transient voltage measuring techniques

Transient voltages continue to cause insulation failures of transformers in a variety of applications. There is evidence that some voltage transients may include frequency components up to 100 mc (megacycles) of substantial peak-to-peak amplitude. Conventional techniques for securing reasonably accurate oscillographic recordings of high-frequency transients were found to be inadequate. Systems were devised which couple the oscillograph to the point of voltage measurement by 50-ohm cables. Through the combination of special signal-cable filters and relatively simple shielding techniques, the effects of spurious signals upon the oscillographic recording of high-frequency transient voltages can be virtually eliminated.