Mitsubishi Electric 800 Series Instruction Manual page 589

6.5.2 Motor or machine is making abnormal acoustic noise
Check
points
Input Disturbance due to EMI when frequency or
signal torque command is given from analog input
(terminal 1, 2, 4).
Parameter
setting
Parameter No carrier frequency noises (metallic noises)
setting are generated.
The motor noise increases due to activation of
the carrier frequency automatic reduction
function when the motor is driven overloaded.
Resonance occurs. (output frequency)
Resonance occurs. (carrier frequency)
Auto tuning is not performed under Advanced
magnetic flux vector control.
Gain adjustment during PID control is
insufficient.
The gain is too high under PM motor control.
Others Mechanical looseness
Contact the motor manufacturer.
Motor Operating with output phase loss
6.5.3 Inverter generates abnormal noise
Check
points
Fan Fan cover was not correctly installed when a
cooling fan was replaced.
588
6. PROTECTIVE FUNCTIONS
6.5 Check first when you have a trouble
Possible cause
Possible cause
Countermeasure
Take countermeasures against EMI.
Increase the Pr.74 Input filter time constant if steady
operation cannot be performed due to EMI.
In the initial setting, Pr.240 Soft-PWM operation selection is
enabled to change motor noise to an unoffending complex tone.
Therefore, no carrier frequency noises (metallic noises) are
generated.
Set Pr.240 = "0" to disable this function.
Reduce the load.
Disable the automatic reduction function by setting Pr.260
PWM frequency automatic switchover = "0".
Set Pr.31 to Pr.36, Pr.552 (Frequency jump).
When it is desired to avoid resonance attributable to the natural
frequency of a mechanical system, these parameters allow
resonant frequencies to be jumped.
Change Pr.72 PWM frequency selection setting.
Changing the PWM carrier frequency produces an effect on
avoiding the resonance frequency of a mechanical system or a
motor.
Perform offline auto tuning.
To stabilize the measured value, change the proportional band
(Pr.129) to a larger value, the integral time (Pr.130) to a slightly
longer time, and the differential time (Pr.134) to a slightly
shorter time.
Check the calibration of set point and measured value.
Check the setting values of Pr.820 Speed control P gain 1 and
Pr.824 Torque control P gain 1 (current loop proportional
gain).
Adjust machine/equipment so that there is no mechanical
looseness.
Check the motor wiring.
Countermeasure
Install a fan cover correctly.
Refer to
page
72
326
179
179
255
179
353
396
155
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Refer to
page
601