8’ - 24’ POWERFOILPLUS™, POWERFOIL™, & WICKERBILL FANS
WWW.BIGASSFANS.COM ©2010 DELTA T CORP. DBA BIG ASS FAN ALL RIGHTS RESERVED
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WWW.BIGASSFANS.COM ©2010 DELTA T CORP. DBA BIG ASS FAN ALL RIGHTS RESERVED
8’ - 24’ POWERFOILPLUS™, POWERFOIL™, & WICKERBILL FANS
Ungrounded Distribution Systems
CAUTION: Allen-Bradley style NEMA type 1 (IP20) fan controllers contain protective MOVs that are referenced to ground.
MOVs are protective devices that will fail open in the event of a voltage surge that may otherwise lead to catastrophic
failure of the VFD. These devices should be disconnected if the controller is to be installed on an ungrounded distribution
system. KBDA NEMA type 4X (IP65) controllers do not provide this option and should only be installed on solidly grounded
distribution systems.
Disconnecting MOVs
To prevent controller damage, the MOVs connected to ground shall be disconnected if the controller is installed on an ungrounded
distribution system where the Line-to-Ground voltages on any incoming phase could exceed 125% of the nominal Line-to-Line voltage.
To disconnect these devices, remove the jumper as shown below.
1. Turn the screw counterclockwise to loosen.
2. Pull the jumper completely out of the variable frequency drive chassis.
3. Re-tighten the screw after jumper removal.
R/L1
S/L2
T/L3
1
2
3
4
Three-Phase
AC Input
Jumper
Powerflex 4
Powerflex 4M
