
7-1
7. Troubleshooting, Fault Diagnostics and Maintenance
7.1 General
AC Drive fault detection and early warning / self-diagnosis function. When the AC Drive detects a fault, a fault
message is displayed on the keypad.
When the AC Drive detects a warning / self-diagnostics error, the digital operator will display a warning or
self-diagnostic code. The fault output does not energize in this case. Once the warning is removed, the system will
automatically return to its original state.
7.2 Fault Detection Function
When a fault occurs, refer to Table 7.2.1 for possible causes and appropriate measures.
Use one of the following methods to restart:
1. Set one of multi-function digital input terminals (03-00 to 03-05) to 17 (Fault reset) and activate the input
2. Press the STOP/RESET button on the keypad.
3. Power down AC Drive, wait until keypad goes blank, and power-up the AC Drive again.
When a fault occurs, the fault message is stored in the fault history (see group 12 parameters).
Table 7.2.1 Fault Information and Possible Solutions
LED Display
Description
Cause
Possible Solutions
Over Current
The AC Drive output current
exceeds the overcurrent level
(200% of the AC Drive rated
current).
● Acceleration / Deceleration time
is set too short.
● Contactor installed on the
output side of AC Drive.
● Motor rating exceeds AC Drive
rating.
● Short circuit or ground fault.
● Extend acceleration /
deceleration time.
● Check the motor wiring.
● Disconnect motor and try
running AC Drive.
Over Current
The AC Drive output current
exceeds the overcurrent level
in acceleration time
● Acceleration time set too short
● Motor rating exceeds AC Drive
rating.
● Short circuit between winding
and motor casing
● Short circuit between wire and
motor ground
● IGBT failure
● Set a longer acceleration
time
● Change to a larger capacity
AC Drive
● Examine motor
● Check wiring
● Replace IGBT module
Over Current
The AC Drive output current
exceeds the overcurrent level
in acceleration time
● Acceleration time set too short
● Motor exceeds AC Drive rating
● Short circuit between motor
winding and motor casing
● Short circuit between wire and
ground of motor
● IGBT failure
● Set a longer acceleration
time
● Change to a larger capacity
AC Drive
● Check motor
● Check wiring
● Replace IGBT module
Over Current
The AC Drive output current
exceeds the overcurrent level
during deceleration
● Deceleration time is set too
short
● Set longer deceleration
time
STO Jumper
The Functional Safety Input
(STO) circuit is open.
● Jumper between SF1/SF2 and
SG terminals has been removed
● User created STO circuit is
open
● Install jumper between
SF1/SF2 and SG terminals
● Adjust user created circuit
to close STO