Mitsubishi Electric FR-A701 Instrucion Manual page 88

(6) Troubleshooting (speed)
Phenomenon
Motor does not rotate.
1
(Vector control)
Motor does not run at
correct speed. (Speed
2
command does not match
actual speed)
Speed does not rise to the
3
speed command.
Cause
(1) The motor wiring is wrong
(2) Encoder specifications (encoder
specification selection switch
FR-A7AP) are wrong
(3) The encoder wiring is wrong.
(4) The Pr. 369 Number of encoder
pulses setting and the number of
encoder used are different.
(5) Encoder power specifications
are wrong. Or, power is not input.
(1) The speed command from the
command device is incorrect.
The speed command is
compounded with noise.
(2) The speed command value
does not match the inverter-
recognized value.
(3) The number of encoder pulses
setting is incorrect.
(1) Insufficient torque.
Torque limit is actuated.
(2) Only P (proportional) control is
selected.
Countermeasures
(1) Wiring check
Select V/F control (set "9999" in Pr. 80 or Pr. 81 ) and
check the rotation direction of the motor.
For the SF-V5RU (1500r/min series), set "160V
(320V)" in Pr. 19 Base frequency voltage, and set "50Hz"
in Pr. 3 Base frequency.
When the forward rotation signal is input,
the motor running in the counterclockwise
direction as viewed from the motor shaft is
normal. (If it runs in the clockwise direction,
the phase sequence of the inverter
secondary side wiring is incorrect.)
(2) Check the encoder specifications.
Check the encoder specifications selection switch
(FR-A7AP) of differential/complementary
(3) Check that FWD is displayed when running the motor
in the counter-clockwise direction from outside during
a stop of the inverter with vector control setting.
If REV is displayed, the encoder phase sequence is
wrong.
Perform the correct wiring or match the Pr. 359 Encoder
rotation direction.
Pr. 359 Relationship between the Motor
Setting and Encoder
0
Encoder
Clockwise direction as viewed
from A is forward rotation
1
(Initial value)
Encoder
Counter clockwise direction as
viewed from A is forward rotation
(4) The motor will not run if the parameter setting is
smaller than the number of encoder pulses used. Set
the Pr. 369 Number of encoder pulses correctly.
(5) Check the power specifications (5V/12V/15V/24V) of
encoder and input the external power supply.
(1) Check that a correct speed command comes from the
command device.
Decrease Pr. 72 PWM frequency selection.
(2) Readjust speed command bias/gain Pr. 125, Pr. 126, C2
to C7 and C12 to C15.
(3) Check the setting of Pr. 369 Number of encoder pulses.
(vector control)
(1) -1 Increase the torque limit value.
(Refer to torque limit of speed control on chapter 4 of
the instruction manual (applied) )
(1) -2 Insufficient capacity
(2) When the load is heavy, speed deviation will occur
under P (proportional) control. Select PI control.
Before operation
CW
A
CCW
A
81
4