leakage current measurement EN60990 - EN60601

Like insulation resistance and high voltage testing, leakage current measurement is about the quality and safety of the insulation.

The leakage current measurement takes place during the operation of the electrical device. For this purpose, the electrical device is connected to the operating voltage and tested to see whether excessive leakage current flows through the insulation to the housing.

So it is a combination of a safety and function test.

Why?
Safe insulation is the central protective measure for electrical safety. It ensures that the user does not come into contact with live conductors and that no short circuit can occur between the conductors or to the equipment housing.

If this were to happen, a life-threatening current would flow through the user if it were to touch the enclosure.
The protective conductor (PE) should ensure that this does not happen, but in the worst case, the earth may also be faulty. It would also only be a prevention of the effect and not the cause.

To ensure all this, the insulation must be in good condition! This must be proven and documented before delivery of the electrical product by means of a leakage current test.

This test is not mandatory for all electrical equipment. However, it may be required for certification of the electrical equipment in the type test. If it is required during manufacturing, it is a production test.

This includes that every electrical product you put on the market must be subjected to a leakage current test.

How?
Since insulation “has something to do with voltage”, the test takes place at an increased nominal voltage. The increase is usually + 6%, + 10% or + 15%.
Reason: since the mains voltage may later be increased by, for example, + 10% at the end customer, this must be simulated during the test. The electrical product is thus in an operating state with overvoltage.

This procedure has the advantage that, as far as possible, all parts of the electrical product are temporarily or permanently energised during the ongoing test.

The test is often referred to as a “hot leakage current test”. Logically, there is also the “cold leakage current test”. In this case, the electrical product is not used. The test voltage here is lower. (Replacement leakage current test).

The aim is to measure the current through the insulation under a wide range of fault conditions. This is the rating criterion for the insulation. It should never exceed a specified maximum current throughout the test period. The upper limit of leakage current can be set differently for each product and in different regions/standards. Therefore, you should take the test parameters from the standard applicable to the product and region.

The current measurement is not just a simple current measurement with a multimeter! No, the user is simulated by various RC networks (resistor/capacitor networks). These are defined in the standards for different, possible fault cases.

The test is performed under various fault conditions that are automatically simulated by our tester.

The leakage current in the protection line of the electrical device is measured.

If there are housing parts on the electrical product that are not connected to the protective conductor, the test is carried out using a test probe.

With this range of requirements, it is of course ideal to use a testing instrument that covers as many of the global standards as possible.

The leakage current measurements up to 1 MHz ?
More and more modern electrical products have integrated electronic components. Very often, switching power supplies are used for internal power supply. These can produce pulse-like leakage currents with very high-frequency components up to 1 MHz. To test these, the leakage current measurement technique must necessarily be dimensioned up to 1 MHz.