Motor Rotates In The Opposite Direction; Speed Greatly Differs From The Setting; Acceleration/Deceleration Is Not Smooth - Mitsubishi Electric FR-F740 EC Instruction Manual

Troubleshooting
7.6.5

Motor rotates in the opposite direction

Check points Possible cause
Main Circuit
Input signal
7.6.6

Speed greatly differs from the setting

Check points Possible cause
Input signal
Parameter
Setting
Load
Parameter
Setting
Motor
7.6.7

Acceleration/deceleration is not smooth

Check points Possible cause
Parameter
Setting
Load
Parameter
Setting
Motor
FR-F700 EC
Phase sequence of output terminals U, V
and W is incorrect.
The start signals (forward rotation, reverse
rotation) are connected improperly.
The polarity of the frequency command is
negative during the polarity reversible ope-
ration set by Pr. 73 "Analog input selec-
tion".
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.
Acceleration/deceleration time is too
short.
Torque boost (Pr. 0, Pr. 46) setting is
improper under V/f control, so the stall
prevention function is activated.
The base frequency does not match the
motor characteristics.
Regeneration avoidance operation is per-
formed
Stall prevention function is activated due
to a heavy load.
Check first when you have troubles
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 polarity of the frequency com-
mand.
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
overcurrent trip (E.OC ).)
Check the capacities of the inverter and
the motor.
Countermeasures
Increase acceleration/deceleration time.
Increase/decrease Pr. 0 "Torque boost"
setting value by 0.5% increments to the
setting.
Set Pr. 3 "Base frequency" and Pr. 47
"Second V/f (base frequency)".
If the frequency becomes unstable during
regeneration avoidance operation,
decrease the setting of Pr. 886 "Regene-
ration avoidance voltage gain".
Reduce the load weight.
Set Pr. 22 "Stall prevention operation
level" higher according to the load.
(Setting Pr. 22 too large may result in fre-
quent overcurrent trip (E.OC ).)
Check the capacities of the inverter and
the motor.
Refer to
page
3-7
3-16
6-188
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page
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3-44
6-54
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6-75
6-39
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