How to measure AC/DC converter isolation voltage using commonly used withstand voltage insulation tests

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AC/DC converter withstand voltage insulation test

Isolation voltage is an important factor to consider when selecting a suitable AC/DC converter, so the value of this parameter is usually listed in the filter box on the Digi-Key website, as shown in the figure below.

Isolation voltage, also known as input-output isolation voltage, is used to indicate the maximum voltage that can be loaded across the converter while maintaining electrical isolation between the input and output. Therefore, isolation voltage can be considered, in part, as the ability of an insulation layer to withstand high transient voltages for several seconds.

Withstand insulation testing is a common method used to measure the isolation voltage of AC/DC converters. For example, the isolation voltage (input-output) listed in the specification sheet of the LPS100-M series of Artesyn embedded power supplies is 4000VAC.

The withstand voltage insulation test system can be set up according to the following figure:

In a nutshell, withstand insulation testing is performed by applying a high voltage from the power input line to the product chassis or secondary output, and then measuring the resulting leakage current through the converter insulation.