Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive (A Frame) - ForGe Control - Manual (Page 182)

182 Rockwell Automation Publication 7000A-UM200C-EN-P - June 2014
Appendix E Meggering
The following procedure details how the Megger test on the PowerFlex 7000A is
to be performed. Failure to comply with this procedure may result in poor
Megger reading and damage to drive control boards.
Equipment Required
• Torque Wrench and 7/16 in. socket
• Phillips Screwdriver
• 2500/5000V Megger
Isolate and Lock Out the Drive System from High Voltage
Disconnect any incoming power sources, medium voltage sources should be
isolated and locked out and all control power sources should be turned off at
their respective circuit breaker(s).
Verify with a potential indicator that power sources have been disconnected, and
that the control power in the drive is de-energized.
Isolate the Power Circuit from System Ground (Float the drive)
It is necessary to remove the grounds on the following components within the
drive (Refer to the electrical diagrams provided with the equipment to assist in
determining the points which need to be disconnected):
• Voltage Sensing Boards (VSB)
• Output Grounding Network (OGN)
Voltage Sensing Boards
Remove all ground connections from all of the VSBs in the drive. This has to be
done at the screw terminals on the VSB rather than the ground bus. There are
two grounds on each board marked “GND 1”, and “GND 2”.
Note: It is important to disconnect the terminals on the boards rather than from
the ground bus as the grounding cable is only rated for 600 V. Injecting a high
voltage on the ground cable will degrade the cable insulation. Do not disconnect
the white medium voltage wires from the VSBs. They must be included in the
test.
The number of VSBs installed in each drive varies depending on the drive
configuration.