10-8
Possible Causes
What to Check and Suggested Measures
(2) An external potentiometer is
used for frequency setting.
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 external frequency command potentiometer is
malfunctioning due to noise from the inverter.
Connect a capacitor to the output terminal of the potentiometer or set a
ferrite core on the signal wire. (Refer to Chapter 2.)
Possible Causes
What to Check and Suggested Measures
(3) Frequency switching or
multi-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.
(4) The wiring length between the
inverter and the motor is too
long.
Check whether auto-torque boost, auto-energy saving operation, or dynamic
torque vector control is enabled.
Perform auto-tuning of the inverter for every motor to be used.
Disable the automatic control systems by setting F37* to "1" (Constant
torque load) and F42* to "0" (V/f control with slip compensation active),
then check that the motor vibration stops.
Make the output wires as short as possible.
(5) The machinery is hunting due
to vibration caused by low
rigidity of the load. Or the
current is irregularly oscillating
due to special motor
parameters.
Once disable all the automatic control systems such as auto torque boost,
auto energy saving operation, overload prevention control, current limiter,
torque limiter, automatic deceleration (anti-regenerative control), auto search
for idling motor speed, slip compensation, dynamic torque vector control,
droop control, overload stop function, speed control, tuning, notch filter,
observer, and then check that the motor vibration comes to a stop.
Disable the functions causing the vibration.
Readjust the output current fluctuation damping gain (H80*).
Readjust the speed control systems. (d01* through d06*)
Check that the motor vibration is suppressed if you decrease the level of F26
(Motor sound (Carrier frequency)) or set F27 (Motor sound (Tone)) to "0."
Decrease the carrier frequency (F26) or set the tone to "0" (F27 = 0).
[ 5 ] Grating sound is heard from the motor or the motor sound fluctuates.
Possible Causes
What to Check and Suggested Measures
(1) The specified carrier frequency
is too low.
Check the data of function codes F26 (Motor sound (Carrier frequency)) and
F27 (Motor sound (Tone)).
Increase the carrier frequency (F26).
Change the setting of F27 to appropriate value.
(2) The surrounding temperature
of the inverter was too high
(when automatic lowering of
the carrier frequency was
enabled by H98).
Measure the temperature inside the panel where the inverter is mounted.
If it is over 40
C (104
F), lower it by improving the ventilation.
Lower the temperature of the inverter by reducing the load. (For fans or
pumps, decrease the frequency limiter value (F15).)
Note:
If you disable H98, an
0h1, 0h3,
or
0lu
alarm may occur.
(3) Resonance with the load.
Check the machinery mounting accuracy or check whether there is resonance
with the mounting base.
Disconnect the motor from the machinery and run it alone, then find where
the resonance comes from. Upon locating the cause, improve the
characteristics of the source of the resonance.
Adjust the settings of C01 (Jump frequency 1) to C04 (Jump frequency
(Hysteresis width)) so as to avoid continuous running in the frequency
range causing resonance.
Enable the speed control (notch filter) (d07*, d08*) and the observer (d18
to d20) to suppress vibration. (Depending on the characteristics of the
load, this may take no effect.)