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Precision

Coming Soon….

The required precision (e.g. +-10μA) of the current leakage measurement (e.g. 60μA) of a hipot will depend on 1.) the required pass/fail borderline isolation (e.g. 50MΩ) of a product and 2.) the test voltage (e.g. 3kV) at which the hipot test is driven with. A precision based on 10% of the pass/fail criteria value for a PV module would be 6μA, at double of the test voltage (e.g. 6kV) 10% precision would be equivalent to 12μA.

In the above example, no consideration is taken to a earth resistor which could strongly influence your final measurement value expressed in MΩ.

Another important factor is the control value of the hipot test device. The controller drives the ramp, when the test voltage is reached, the controller immediately has to regulate the test voltage. Most controllers will drive over the value by a few percent and regulate back down. This causes a distinct “jump” in the graph [V] vs. [A]. This usually happens within approx 0,5s of reaching the test voltage.

… to be continued …