METREL MI 3399, Инструкция с упражнениями

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PAT Appliances & Machines Safety Trainer AD 3
– MI 3399
220
Measurement on a class II appliance:
Figure 4-9: Example of the insulation test on a Class II appliance
High DC voltage test signal is applied between connected live pins and accessible
conductive parts separated from protective circuit. Each accessible conductive part shall
be tested separately.
Notes:

On/Off switches must be closed. If after the switches were closed all safety relevant
parts are not included the results will be impaired. This is often the case in
electronic or relay driven On/Off circuits. In this case leakage current tests can be
performed as an alternative.

This test cannot be applied on Class II appliances without accessible conductive
parts.

The sub-leakage test is recommended to be performed after the insulation test too.

Test voltage level is usually selected in the same level as maximum possible
supply voltage.

IT equipment not designed according to EN 60950 can be damaged by the 500 V
test voltage.
4.4.4 Sub-leakage test
Scope of test
Overall impedance between live conductors and all accessible conductive parts (earthed
and isolated) is checked with this test. Capacitive leakage paths (input filter capacitors,
transformers, cables…) are included in the result, too.
In this test the live and neutral conductors of the appliance are shorted together and
voltage of 30 - 50 V AC is applied between this point and either the earth conductor (class
I) or the probe connected to any exposed conductive part (class I and class II). The test
measures how much current passes from the live conductors into the test point.