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38 Electrical installation
Isolation from common DC bus
In case of units with DC voltage remaining: if there are several power sources for the DC
bus, the supply unit which shall be isolated must be equipped with a DC switch-disconnector
(option +F286). In order to isolate the supply unit from the live DC bus, open the DC
switch-disconnector [Q11] and also the charging switch [Q10] in EVERY cubicle containing
supply modules. In addition, open the DC switch-disconnector of the AC circuit [Q40].
1. Clearly identify the work location.
2. Disconnect all possible voltage sources. Note that energy to the DC bus can also be
fed back by motors, energy storages, etc.
•
Make sure that reconnection is not possible. Lock the disconnectors to open position
and attach a warning notice to them.
•
Disconnect any external power sources from the control circuits before you do work
on the control cables.
•
After you disconnect the drive, always wait for 5 minutes to let the intermediate
circuit capacitors discharge before you continue.
3. Protect any other energized parts in the work location against contact.
4. Take special precautions when close to bare conductors.
5. Measure that the installation is de-energized.
•
Use a multimeter with an impedance of at least 1 Mohm.
•
Make sure that the voltage between the drive input power terminals and the
grounding (PE) busbar is close to 0 V.
6. Install temporary grounding as required by the local regulations. Connect the DC busbars
to PE with a temporary grounding tool.
7. Ask for a permit to work from the person in control of the electrical installation work.
Checking the insulation of the assembly
￭
Checking the insulation of the drive system
WARNING!
Do not make any voltage withstand or insulation resistance tests on any part of
the drive as testing can damage the drive. Every drive has been tested for insulation
between the main circuit and the chassis at the factory. Also, there are
voltage-limiting circuits inside the drive which cut down the testing voltage
automatically.
￭
Checking the insulation of the input cable
Before you connect the input power cable to the drive, check its insulation according to local
regulations.
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