3BHS135824 ZAB E01Rev. D 29 (of 62)
Chapter 6 - Insulation Resistance Measurement
Before any of the drive system components is energized, the insulation
resistance of each component must be measured to verify their ablility
to withstand voltage stress. The results of the measuremnets must be
noted in the commissioning record.
The water conductivity must be lower than 0.5 µS during the insulation
check of the converter. In case you need to wait for the conductivity to
come down you can proceed with the section about parameter
settings.
In case checks of motor and transformer are included in the
commissioning, refer to the applicable manual for additional
information. It is also advisable to compare the measured results with
the test reports from the supply factory.
6.1 Type of Measuring Device
The insulation test of the ACS 6000 drive system is carried out with a
test voltage of 5 kV DC. Since the insulation resistance of a mult-drive
converter may be as low as 0.5 MΩ a megger with a current capability
of 2 mA is required. These devices are not common. Therefore it is
important that such the megger is ordered in time.
If a less powerful megger is used and the 5 kV test voltage cannot be
reached smaller the converter has to be tested in smaller sections. To
do this the section to be tested is isolated from the adjacent sections
by opening the busbar connectors.
6.2 Preparations for the Measurement
Before starting the insulation measurements do the following:
1 Check that the power cables are disconnected and securely
grounded.
2 Make sure that the main circuit breaker is not able to close (by
means of mechanical interlocking).
Note that the grounding switch of the ACS 6000 must be in the
unearthed position during the measurement.
3 Make sure that no energy can be fed from the motor side.
No motor must be rotating.
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