Voltage Endurance Testing

Assessing the lifetime of an insulation system is an essential step when delivering high voltage products. Failing to do so can mean the insulation system reaches end of life prematurely.

Voltage endurance testing is particularly important when designers seek to deliver partial discharge (PD) resistant systems – avoiding the increasingly large insulation thicknesses that may be required to be partial discharge free. Many manufacturers of insulation for electrical machines produce ‘corona resistant’ forms that are meant to have extended lifetimes.

However, corona resistant / PD resistant insulation will still fail given time – particularly in situations where the insulation is used in conjunction with high frequency power electronics. As such, it’s important that there is the ability to test and compare the performance of different insulation materials to understand the expected time to failure in operation.

At aHV, we’ve built up capability to ensure that insulation systems can be tested using a range of voltage types mimicking those found in power electronic systems with tests also being run in the appropriate environment. This allows us to deliver accurate data that can be used to confirm that the insulation system will survive in the application.


Relevant Standards

Voltage endurance/lifetime tests can be guided by a range of standards that including:
• IEC 61251 - Electrical insulating materials and systems — A.C. voltage endurance evaluation

• GB/T 4074.21_Winding wires test methods—Part 21: Electrical endurance under high frequency voltage impulses

• ASTM D2275-01: Standard Test Method for Voltage Endurance of Solid Electrical Insulating Materials Subjected to Partial Discharges (Corona) on the Surface

• IEC 62539 _Guide for the statistical analysis of electrical insulation breakdown data.

Standards are rapidly developing in this area, particularly in respect of the capability of insulation systems to manage partial discharge when squarewave voltages are applied.

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Test Services

aHV can test insulation materials and entire components such as cabling, laminated busbars, PCBs and electrical machines. All the tests can be done at different voltage levels and environments (pressure, temperature).

This service typically involves:

Pre-Test Assessment: The PD inception voltage (PDIV) and breakdown voltage (BDV) of the samples will be assessed before an endurance test. This serves as an important reference to ensure the voltage applied during the test is reasonable (the test is usually carried out above the partial discharge inception voltage unless the insulation system is intended to operate in a partial discharge free mode).

Electrical Endurance Test: In this test, samples will be exposed to PD continuously until breakdown is detected. Ten samples can be tested in parallel and tests can be carried out with DC, AC (50Hz – 2000Hz) or squarewaves (up to 100kHz) at voltages of up to 30kV. Computer software records the time-to-failure of each sample from which a Weibull distribution of time to failure can be generated. By carrying out this test at multiple voltages, we can then predict what the time to failure will be in the application.

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Measurement Of Erosion: A unique capability at aHV is our ability to image the damage that partial discharge has caused. This is typically done after a test of a specific duration in which samples are exposed to partial discharge continuously. Through the use of laser confocal microscopy, we can then image the surface to a 1µm accuracy level and understand the rate by which the insulation is being eroded generating improved insights into the failure mode of the insulation. 

Contact Us

To discuss your requirements for an electrical endurance testing compatibility assessment, please speak to Richard Gardner, our Senior Engineer & High Voltage Lab Manager.
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