partial discharge testing

One of the main functions of power transformer is to provide isolation between two sections of an electronic circuit. This isolation may be necessary to comply to a relevant safety specification to ensure the safety of users or to protect sensitive circuits from high voltages or transients. In general, the isolation required is set by the voltage present in the circuit and the level of safety insulation that is required. Although the design of the magnetic can ensure that the isolation requirements are met in principle, it cannot ensure that certain defects, due to variations in materials or manufacturing processes, will not lead to failures through time. It is therefore necessary to apply some sort of test to the components to evaluate the integrity of the insulation. The most commonly used method is a hi-pot or dielectric strength test in which a high voltage is applied to each side of the isolation barrier and the leakage current is measured. The problem with a hi-pot test is that the voltage (or resultant leakage current) can damage the insulation and weaken the resultant product. In addition, hi-pot testing is not effective at identifying certain long-term failure mechanisms. An alternate and far less destructive method for evaluating the insulation barrier is the partial discharge test. Partial discharge testing looks at the distribution of charge during an ionization cycle and is a more precise evaluation of potential problems.


“With the proliferation of high voltage energy storage systems in EV, HEV and alternative energy there is a growing awareness of the need for a better method, especially in small form factor transformers, of ensuring the integrity of the insulation barrier”

Shreyankh Krishnamurthy, Product Marketing, Pulse Electronics


In an effort to explain the need for partial discharge testing and detailing the test procedure Pulse Electronics has released a white paper Partial Discharge Testing Explained. For more information on Pulse products please visit our website or for specific information about our high voltage low power isolation transformers check out our product overview.

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