Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 280)

280 Rockwell Automation Publication 7000-UM151E-EN-P - January 2013
Appendix D Meggering
Following this procedure to perform Megger tests on the PowerFlex 7000B.
Failure to comply with this procedure may result in poor Megger reading and
damage to drive control boards.
Meggering Procedures Required Equipment
• Torque Wrench and 7/16 inch socket
• Phillips Screwdriver
• 2500/5000 Volt Megger
Procedure
1. Isolate and lock out the drive system from any high voltage source.
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.
2. Isolate the power circuit from system ground (“float the drive”).
You must 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 to disconnect):
• Voltage Sensing Boards (VSB)
• Output Grounding Network (OGN)
Voltage Sensing Boards
a. Remove all ground connections from all of the VSBs in the drive. Do
this 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.
Output Grounding Network
b. Remove the ground connection on the OGN (if installed). Lift this
connection at the OGN capacitor rather than the grounding bus, as the
grounding cable is only rated for 600 V.
Note: Injecting a high voltage on the ground cable during a Megger test
will degrade the cable insulation.