BENSHAW RSi-030-SG-4B, Service Manual

Page: 94 / 116

Pub # 890046-10-00
Dec. 2015
Section 4, Page
12
of
32
4.4 Ground Fault
Fault Display:
Ground Fault
Auto Resettable
: No
Related parameters:
DRV-05, DRV-30, MAK-26
Description:
The drive has detected a level of ground current higher than the programmed
ground fault setting in the drive. Parameter MAK-26 is set as a percentage of motor amps
(DRV-05). When running, the ground current can be viewed at parameter DRV-30.
Background:
Ground fault monitoring is done residually. The instantaneous values of the three
phase output currents are monitored and summed. Under ideal conditions the vector sum would
be zero. Any difference is assumed to be ground current.
Fault Causes Solutions
Ground Fault Output Short Circuit ‐
motor or cables.
With motor leads disconnected from drive,
Ohm check phase ‐ phase and phase ‐ ground.
Meggar test including motor leads.
Output Short Circuit ‐
IGBT's
With motor leads disconnected, restart drive.
If drive still trips on ground fault or OC ‐ 2, drive
IGBT short. See Power Device checks.
Single Phase output from
drive.
With no motor connected, measure phase ‐
phase voltage output at 60 Hz.
Ground Current setting
too low.
Increase ground current percentage,
parameter MAK ‐ 26. See adjustment below.
IGBT gate firing circuit Pull and reseat IGBT connectors CN19 through
CN24 at bottom of the Main SMPS board.
Missing Feedback Signal Larger drives (> 150 HP) The Main SMPS board
receives feedback current signals from LEM’s,
Check the connection at the Main SMPS
board, connectors CN1, CN2, CN3.
SMPS Board malfunction Replace Main SMPS board.
Line Voltage Imbalance The spec for voltage input imbalance is +/ ‐ 2%.
This can cause an imbalance in the output
voltages, leading to imbalance of current,
which is the main detection for ground fault
current. Partial solution is line reactor.