6-5
Possible Causes
What to Check and Suggested Measures
(9) Bias and gain incorrectly
set.
Check the data of function codes F18, C50, C32, C34, C37, and
C39.
Readjust the bias and gain to appropriate values.
[ 3 ] The motor runs in the opposite direction to the command.
Possible Causes
What to Check and Suggested Measures
(1) Wiring to the motor is
incorrect.
Check the wiring to the motor.
Connect terminals U, V, and W of the inverter to the U, V, and W
terminals of the motor, respectively.
(2) Incorrect connection
and settings for run
commands and rotation
direction command
FWD
and
REV
.
Check the data of function codes E98 and E99 and the connection
to terminals [FWD] and [REV].
Correct the data of the function codes and the connection.
(3) A run command (with
fixed rotation direction)
from the keypad is active,
but the rotation direction
setting is incorrect.
Check the data of function code F02 (Run command).
Change the data of function code F02 to "2:
/
keys on
keypad (forward)" or "3:
/
keys on keypad (reverse)."
[ 4 ] Speed fluctuation or current oscillation (e.g., hunting) occurs during running at
constant speed.
Possible Causes
What to Check and Suggested Measures
(1) The frequency
command fluctuates.
Check the signals for the frequency command with Menu #4 "I/O
Checking" using the keypad.
Increase the filter constants (C33, C38) for the frequency
command.
(2) An external frequency
command potentiometer
is used.
Check that there is no noise in the control signal wires from external
sources.
Isolate the control signal wires from the main circuit wires as far
as possible.
Use shielded or twisted wires for control signals.
Check whether the frequency command has not failed because of
noise from the inverter.
Connect a capacitor to the output terminal of the potentiometer or
set a ferrite core on the signal wire. (See Figure 2.7.)
(3) Frequency switching or
multistep frequency
command was enabled.
Check whether the relay signal for switching the frequency
command is chattering.
If the relay contact is defective, replace the relay.
