Rockwell Automation Publication 520-QS001A-EN-E - March 2014 5
PowerFlex 520-Series Adjustable Frequency AC Drive
Ungrounded Distribution Systems
Disconnecting MOVs
To prevent drive damage, the MOVs connected to ground shall be disconnected if the drive is installed on an ungrounded
distribution system (IT mains) where the line-to-ground voltages on any phase could exceed 125% of the nominal line-to-
line voltage. To disconnect these devices, remove the jumper shown in the diagrams below.
1. Turn the screw counterclockwise to loosen.
2. Pull the jumper completely out of the drive chassis.
3. Tighten the screw to keep it in place.
Jumper Location (Typical)
Phase to Ground MOV Removal
CE Conformity
See the PowerFlex 520-Series Adjustable Frequency AC Drive User Manual, publication 520-UM001 for details on how to
comply with the Low Voltage (LV) and Electromagnetic Compatibility (EMC) Directives.
ATTENTION: PowerFlex 520-Series drives contain protective MOVs that are referenced to ground. These devices must be
disconnected if the drive is installed on an ungrounded or resistive grounded distribution system.
ATTENTION: Removing MOVs in drives with an embedded filter will also disconnect the filter capacitor from earth ground.
Tighten screw after jumper removal.
R/L1
S/L2
T/L3
1234
Three-Phase
AC Input
Jumper
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