Leakage current test devices

Leakage current test devices serve for the standard-compliant verification of the electrical safety of devices and systems. Leakage current refers to the current that flows via the insulation or capacitive couplings from live parts to grounded parts or to the housing. To ensure the safety of persons and devices, it must not exceed certain limit values.

The leakage current test device applies a defined operating voltage to the device under test and measures the current flowing through the protective earth conductor or non-conductive parts.

Measurements are performed according to relevant standards such as:

• DIN EN 60601 (Medical Technology)
• DIN EN 60335 (Household Appliances)
• DIN EN 60950 / 62368 (IT and Audio/Video devices)
• UL regulations
• etc.

During the leakage current test, the magnitude of the current is determined that flows from the live conductors to the protective earth conductor or to housing parts due to insulation weakness and/or design. Various test regulations (e.g., VDE, EN, IEC, UL …) prescribe the measurement and evaluation of the leakage current.

Why the leakage current test is so important.

Electrical devices can only be operated safely if they possess high electrical insulation strength. In the worst case, poor insulation can lead to electrical accidents with severe injuries or even fatal consequences.

The inspection of the electrical product typically occurs with a test voltage that is a percentage value, specified in the standard, above the product's nominal voltage. Often, this value corresponds to 1.1 times the nominal voltage.

What types of leakage current test are there?

The leakage current can be measured in two ways:

The device under test is in function

• • The standard refers to procedure A
  • This method is also known as the “Warm leakage current test”.
  • The test voltage is fed in single-phase between the device under test connections L and N.
    • There are two ways of feeding in here:
      • A1:  L to Phase – N to Neutral
      • A2:  N to Phase – L to Neutral

• • The test voltage is fed in three-phase between the device under test connections L1, L2, L3 and N.
    • There are four ways of feeding in here:
      • L1, L2, L3, N  / Normal condition
      • open, L2, L3, N  / fault condition
      • L1, open, L3, N  / fault condition
      • L1, L2, open, N  / fault condition

The device under test is not in function

• • The standard refers to method B.
  • This method is also referred to as "Cold leakage current test".
  • The TEST VOLTAGE is applied between the bridged device under test connections L and N against the protective earth conductor.

What are the typical standards?

Globally, two standards are of central importance in Europe:

EN60990 – Procedure for measuring touch current and protective earth conductor current

• • Touch current on accessible metal parts of the device under test
  • Leakage current in the protective earth conductor of the device under test

EN60601 – Procedure for measuring leakage currents on medical products and systems

• • Touch current on accessible metal parts of the device under test
  • Leakage current in the protective earth conductor of the device under test
  • Leakage current on patient connections, etc.
  • Various types of patient leakage currents under various fault conditions
  • Various types of patient auxiliary currents under various fault conditions
  • Measurement of leakage current with frequency components up to 1 MHz

For all European and worldwide standards, such as UL, and their respective applications, SCHLEICH provides the appropriate test devices.

What are the "pass/fail" criteria?

The evaluation of the leakage current test is always based on the current magnitude. It must not exceed an adjustable limit.

What is an MD?

The MD (Measurement Device) is a measuring circuit consisting of resistors and capacitors for determining the leakage current. In principle, it simulates the person at risk through whom the leakage current would flow in case of a fault.

Various MD variants are listed in the standards. All these variants can be integrated into a SCHLEICH leakage current test device.

What is the substitute leakage current test?

The substitute leakage current test is a cold leakage current test according to Method B, however, with a reduced TEST VOLTAGE of, for example, 40 V AC. The current flowing during this process is then extrapolated proportionally to the current that would flow at 110% nominal voltage.

Here's how to find the suitable leakage current test device.

If you only want to run the leakage current test on your device under test, a single test device is the right choice. However, this already includes two test methods: the function test and the leakage current test.
The function test is required to operate the device under test according to procedures A1/A2 under voltage.

If the device under test also requires a more comprehensive safety and function check, we recommend our combination test devices/multifunction testers. With these, various test methods, such as insulation, high-voltage, and protective earth resistance tests, can be conveniently combined in one device. The test method switch-over in the device ensures that no measurement leads need to be manually reconnected at the device under test during the test.

Thanks to the intuitive and convenient operation of our leakage current test devices, every test is performed quickly, precisely, and cost-effectively.