Leakage current testers

Leakage current testers are used to verify the electrical safety of devices and systems in accordance with standards. Leakage current refers to the current that flows through insulation or capacitive couplings from live parts to grounded parts or to the housing. To ensure the safety of people and equipment, it must not exceed certain limit values.

The leakage current tester applies a specified operating voltage to the test object and measures the current that flows through the protective conductor or non-conductive parts.

Measurements are performed in accordance with relevant standards, such as:

• DIN EN 60601 (Medical Technology)
• DIN EN 60335 (Household Appliances)
• DIN EN 60950 / 62368 (IT and audio/video equipment)
• UL regulations
• etc.

Leakage current testing determines the amount of current that flows from live conductors to the protective conductor or to parts of the enclosure due to insulation failure and/or design-related factors. Various testing standards (e.g., VDE, EN, IEC, UL, etc.) require the measurement and evaluation of leakage current.

Why leakage current testing is so important.

Electrical appliances can only be operated safely if they have a high level of electrical insulation resistance. In the worst-case scenario, poor insulation can lead to electrical accidents resulting in serious injury or even death.

Electrical products are typically tested using a test voltage that is a certain percentage higher than the product's rated voltage, as specified in the standard. This value is often 1.1 times the rated voltage.

What types of leakage current testing are there?

Leakage current can be measured in two ways:

The test object is operational

• • The standard refers to Procedure A
  • This method is also known as a "hot leakage current test"
  • The test voltage is applied as a single-phase voltage between the test object terminals L and N
    • There are two options for feeding power into the grid:
      • A1: L to phase – N to neutral
      • A2: N to phase – L to neutral

• • The test voltage is applied in three phases between the test object terminals L1, L2, L3, and N
    • There are four ways to feed power into the grid:
      • L1, L2, L3, N / Normal state
      • Open, L2, L3, N / Error condition
      • L1, open, L3, N / Fault condition
      • L1, L2, open, N / Error condition

The test object is not operational

• • The standard refers to Procedure B
  • This method is also known as a "cold leakage current test"
  • The test voltage is applied between the bridged test object terminals L and N relative to the PE

What are some typical standards?

Globally, two standards are of central importance in Europe:

EN 60990 – Methods for measuring touch current and protective conductor current

• • Touch current on accessible metal parts of the test object
  • Leakage current in the protective conductor of the test object

EN 60601 – Methods for measuring leakage currents in medical devices and systems

• • Touch current on accessible metal parts of the test object
  • Leakage current in the protective conductor of the test object
  • Leakage current at patient connections, etc.
  • Various types of patient leakage currents under a wide range of fault conditions
  • Various types of patient assistance currents under a wide range of fault conditions
  • Measurement of leakage current with frequency components up to 1 MHz

SCHLEICH offers the appropriate testing equipment for all European and global standards, such as UL, and their respective applications.

What are the "good/bad" criteria?

The evaluation of the leakage current test is always based on the current level. It must not exceed a preset limit.

What is an MD?

The MD (Measurement Device) is a measurement circuit consisting of resistors and capacitors designed to measure leakage current. In principle, it simulates the person at risk through whom the leakage current would flow in the event of a fault.

The standards list various MD variants. All of these variants can be integrated into a SCHLEICH leakage current tester.

What is the substitute leakage current test?

The substitute leakage current test is a cold leakage current test conducted according to Method B, but with a reduced test voltage of, for example, 40 V AC. The current flowing during the test is then extrapolated to be proportional to the current that would flow at 110% of the rated voltage.

Here's how to find the right leakage current tester.

If you only want to perform a leakage current test on your test object, a single-unit tester is the right choice. However, this device already includes two test methods: the functional test and the leakage current test.
The functional test is required to operate the test object under voltage in accordance with methods A1/A2.

If the test object also requires a more comprehensive safety and functional check, we recommend our combination testers/multifunction testers. These devices conveniently combine various test methods—such as insulation, high-voltage, and protective conductor resistance testing—into a single unit. The test method switching feature in the device ensures that no test leads need to be manually reconnected to the test object during the test.

Thanks to the intuitive and user-friendly operation of our leakage current testers, every test is performed quickly, accurately, and cost-effectively.