Motor Generates Heat Abnormally - Mitsubishi Electric FR-D720S SC EC Instruction Manual

Check first when you have troubles
7.6.4

Motor generates heat abnormally

Check points Possible Cause
Motor
Main Circuit
Parameter
Setting
—
7.6.5 Motor rotates in opposite direction
Check points Possible Cause
Main Circuit
Input signal
Parameter
Setting
7.6.6 Speed greatly differs from the setting
Check points Possible Cause
Input signal
Parameter
Setting
Load
Parameter
Setting
Motor
7 - 24
Motor fan is not working
(Dust is accumulated.)
Phase to phase insulation of the motor is
insufficient.
The inverter output voltage (U, V, W) are
unbalanced.
The Pr. 71 "Applied motor" setting is
wrong.
Motor current is large.
Phase sequence of output terminals U, V
and W is incorrect.
The start signals (forward rotation, reverse
rotation) are connected improperly.
Adjustment by the output frequency is
improper during the reversible operation
with Pr. 73 "Analog input selection" set-
ting.
Pr. 40 "RUN key rotation direction selec-
tion" setting is incorrect.
Frequency setting signal is incorrectly
input.
The input signal lines are affected by
external EMI.
Pr. 1, Pr. 2, Pr. 18, calibration parameter
C2 to C7 settings are improper.
Pr. 31 to Pr. 36 "Frequency jump" settings
are improper.
Stall prevention is activated due to a heavy
load.
Countermeasures
Clean the motor fan.
Improve the environment.
Check the insulation of the motor.
Check the output voltage of the inverter.
Check the insulation of the motor.
Check the Pr. 71 "Applied motor" setting.
Refer to "7.6.11 Motor current is too large"
Countermeasures
Connect phase sequence of the output
cables (terminal U, V, W) to the motor cor-
rectly
Check the wiring. (STF: forward rotation,
STR: reverse rotation)
Check the setting of Pr. 125, Pr. 126, C2 to
C7.
Check the Pr. 40 setting.
Countermeasures
Measure the input signal level.
Take countermeasures against EMI such
as using shielded wires for input signal
lines.
Check the settings of Pr. 1 "Maximum fre-
quency", Pr. 2 "Minimum frequency",
Pr. 18 "High speed maximum frequency".
Check the calibration parameter C2 to C7
settings.
Narrow down the range of frequency jump.
Reduce the load weight.
Set Pr. 22 "Stall prevention operation level
"higher according to the load. (Setting Pr.
22 too large may result in frequent over-
current trip (E.OC ).)
Check the capacities of the inverter and
the motor.
Troubleshooting
Refer to
Page
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8-2
6-72
7-28
Refer to
Page
3-6
3-13
6-153
6-282
Refer to
Page
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3-44
6-40
6-153
6-42
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6-33
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