Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - Classic Control - Manual (Page 491)

Meggering D-3
7000 “B” Frame 7000-UM150I-EN-P – June 2013
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
Remove the ground connection on the OGN (if installed).
This connection should be lifted 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.
3. Disconnect Connections between Power Circuit and Low
Voltage Control
Voltage Sensing Boards
Disconnect connections between the low voltage control and
the power circuit are made through ribbon cable connectors.
The cables will be plugged into connectors on the Voltage
Sensing Board marked “J1”, “J2”, and “J3”, and terminate
on the Signal Conditioning Boards. Every ribbon cable
connection made on the VSBs should be marked for
identification from the factory. Confirm the marking
matches the connections, and disconnect the ribbon cables
and move them clear of the VSB. If these ribbon cables are
not removed from the VSB, then high potential will be
applied directly to the low voltage control through the SCBs,
and cause immediate damage to those boards.
Note: The VSB ribbon cable insulation is not rated for the
potential applied during a Megger test. It is important to
disconnect the ribbon cables at the VSB rather than the SCB
to avoid exposing the ribbon cables to high potential.