PAT Appliances & Machines Safety Trainer
AD 3
– MI 3399
235
Functional tests.
4.5.3 Safety
– measurements
Testing the safety of machines and switchboard uses the same testing techniques as
when performing PAT tests. In addition to those five more tests have to be performed
where the functional test an actual enhancement of the PAT test:
High voltage withstanding test
Loop impedance and prospective fault current
RCD testing
Discharge Time
Functional test
4.5.3.1 High voltage withstanding test
The HV withstanding test is used to confirm integrity of the insulation materials. During
the test the insulation materials in the machine are stressed with a higher voltage than
during normal operation. A powerful AC high voltage source is applied between the live/
neutral input terminals and the metal housing of the machine. The instrument trips out if
the leakage current exceeds the predefined limit.
Figure 4-33: HV withstanding test
Components and devices that are not rated to withstand the test voltage shall be
disconnected during the testing. Components and devices that have been voltage tested
in accordance with their product standards may be disconnected during testing.
4.5.3.2 Loop impedance and prospective fault current
The instrument measures the impedance of the fault loop and calculates the prospective
fault current. The results can be compared to limit values set on base of selected
protective circuit breakers or RCDs. The measurement complies with requirements of the
standard EN 61557-3.
Summary of Contents for MI 3399
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