METREL MI 3399, Instruction Manual With Exercises

Page: 225 / 272

PAT Appliances & Machines Safety Trainer AD 3
– MI 3399
225

If the position of line and neutral conductor in the installation or appliance plug is
not predefined, the test must be performed in both directions with higher result
considered.
4.4.7 Differential leakage current test
Differential leakage measures the difference in current between the live and neutral cable
which provides a true value of how much current the appliance leaks to ground.
Figure 4-17: Differential leakage current test for Class I device
Scope of test
See chapter 4.4.5 Leakage current tests
– general for more details.
Examples of faults
See chapter 4.4.4 Sub-leakage test for more details.
Measuring principle / limits
Measurement on Class I appliance:
Figure 4-18: Example of differential leakage current test
The appliance must be powered on. The leakage current is measured as the difference
of currents through L and N supply conductors. The result does not depend on what floor
the appliance is placed.