Notes:
- Tested device must be turned on.
- Test circuit is electrically isolated from the mains and from mains' PE lead.
- Test voltage is 25 V...50 V rms.
- I
SUB
current is measured at <50 V voltage and its value is rescaled to the nominal mains voltage
value set in the menu (see section 3). The resistance of the measuring circuit is 2kΩ.
4.2.5 Measurement of differential leakage current - I
Δ
(only PAT-2E and PAT-
10)
This test is performed to evaluate the condition of insulation of the tested device by determining the
value of leakage current. Leakage current flows from live parts, through insulation, to earth. The leak-
age current includes: current flow through the insulation and capacitances in the device (among oth-
ers from filtering or control systems).Leakage current affects operating safety and, sometimes, caus-
es interference within the power grid.
Particular attention is required for testing devices that are operated in severe conditions, heavy dusti-
ness or high humidity.
Differential leakage current is measured as a difference between L current and N current, for all pro-
tection class devices. This measurement takes into account not only PE leakage current (for Class I
devices), but also leakage currents caused by other earthed elements - e.g. water pipe. The meas-
urement result is a sum of all leakages present in the device. This test can be performed only when
the tester is connected to mains. During the measurement the tester automatically changes the polar-
ity of the test socket and repeats the measurement. As a test result it displays the value of the higher
leakage current.
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