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Understanding AC vs DC Hipot Testing

ATEC BLOG

High potential, or hipot, testing is generally used to test the dielectric strength of insulation to ensure the ground wall can handle over-voltage situations. An over-voltage is a voltage that is higher than the DUT’s (device under test’s) peak line-to-line operating voltage, which is typically 1.41 x RMS voltage. If left untested, these over-voltages can damage or reduce the lifespan of the DUT, create blackouts, data loss, or IT system failures.

Hipot testing can be used for low voltage devices, as well as high voltage equipment. There are a variety of factors that help those performing the test decide what hipots apply to their specific needs, specifically, whether they need to use an AC hipot, or a DC hipot. Keep reading this blog to learn more about the comparison between AC and DC hipots and their distinct use cases.

AC Hipot Testing

AC hipot testing places a high voltage to on DUT, checking how well the insulation performs when tested under real-world AC operating conditions. Most electrical systems run on AC power. As such, AC hipot testing is required more frequently than DC hipot testing because AC hipots can test more real-world applications. Some of these real-world applications include testing:

General AC devices
Double-insulated products
Medical devices
Capacitive loads
Identifying partial discharges
Solar PV modules, inverters (Could use DC testing depending on Specs)

DC Hipot Testing

DC hipot testing differs from AC hipot testing because it is more situational. It makes more sense for circumstances where the DUT has a high capacitance or where DC performance is required. Some of these DC hipot testing applications include:

High-voltage cables and harnesses
Devices with large capacitors or EMI Filters
Solar PV modules, inverters (Could use AC testing depending on specs)
Detecting absorption current
Stress testing insulation

Posted April 24, 2026

Comparing AC and DC Hipot Testing

Each form of Hipot testing has its pros and cons depending on the situation they are being used for. Their differences are what make them applicable to different types of equipment.

AC: Alternates positive and negative polarity. There are no polarity concerns because both ends of the insulation are stressed equally during testing.

DC: Applies a single positive or negative polarity, stressing insulation in only one direction.

AC: Offers a continuous charging current. AC produces higher leakage currents than DC due to capacitive charging.

DC: Has a lower current after initial charge, providing stable readings once capacitive charging is complete.

AC: The DUT doesn’t need discharge because the voltage returns to zero every half cycle.

DC: The DUT requires manual or auto-discharge, especially for high capacitance units.

AC: Required for most safety standards. AC testing is widely accepted for regulatory standards such as UL, IEC, CSA for consumer and industrial electronics.

DC: Accepted for more specified applications. More limited in what standards it can satisfy, with some regulatory standards still require AC testing.

AC: Has a higher power demand to maintain consistent output.

DC: Requires less power, and as such, can use smaller, more efficient test equipment.

AC: Measures capacitive and resistive components of leakage current.

DC: Primarily measures resistive components of leakage current.

How ATEC Can Help

ATEC rents a variety of AC and DC Hipot testers from leading manufacturers such as High Voltage Inc. and HV Diagnostics. Reach out to ATEC today to learn more about our broad inventory of Hipot testers.

High Voltage PTS-200

0 - 200kV DC @ 5mA
Negative Polarity
Positive Ground

Learn More About the PTS-200

HV Diagnostics HVA60

62kV peak
44kV RMS @ 40mA
Positive and Negative Polarity

Learn More About the HVA60

High Voltage PFT-1003CM

0 - 100kV AC
Up to 30mA Current
3kVA: 1 hour ON, 1 hour OFF

Learn More About the PFT-1003CM