Is it true that to prevent damage during an AC hipot test, some testers apply voltage at a Very High Frequency (VHF)?

The statement is inaccurate because applying voltage at Very High Frequency (VHF) during an AC hipot test is generally not a standard practice for preventing damage. Instead, traditional AC hipot testing typically involves supplying a continuous waveform voltage at standard frequencies, usually 50 or 60 Hz.

Using VHF might result in certain phenomena that could lead to misinterpretation of test results or even potential risks to insulation systems, as the dielectric properties of materials can be different at higher frequencies compared to standard AC frequencies. Therefore, it is generally not true that VHF is employed in the manner described to avoid damage during an AC hipot test.