Mitsubishi Electric FR-A700 Instruction Manual page 158

Simple mode parameter list
Phenomenon
Motor does not run at cor-
rect speed. (Speed com-
2
mand does not match
actual speed)
Speed does not rise to the
3
speed command.
4 Motor speed is unstable.
Motor or machine hunts
5 (vibration/noise is pro-
duced).
Tab. 5-10: Troubleshooting (2)
5 - 38
Cause
(1) The speed command from the
command device is incorrect.
The speed command is com-
pounded 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.
(1) The speed command varies.
(2) Insufficient torque.
(3) The speed control gains do not
match the machine. (machine
resonance)
(1) The speed control gain is high. (1)-1 Perform easy gain tuning. (Refer to sec-
(2) The torque control gain is high. (2) Decrease the Pr. 824 value. (Refer to sec-
(3) The motor wiring is wrong.
Countermeasures
(1) Check that a correct speed command
comes from the command device.
Decrease Pr. 72 "PWM frequency selec-
tion".
(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 in section
6.3.3.)
(1)-2 Insufficient capacity
(2) When the load is heavy, speed deviation
will occur under P (proportional) control.
Select PI control.
(1)-1 Check that a correct speed command
comes from the command device.
(Take measures against noises.)
(1)-2 Decrease Pr. 72 "PWM frequency
selection".
(1)-3 Increase Pr. 822 "Speed setting filter 1".
(Refer to section 6.20.4.)
(2) Increase the torque limit value. (Refer to
torque limit of speed control in section
6.3.3.)
(3)-1 Perform easy gain tuning. (Refer to sec-
tion 5.1.11).
(3)-2 Adjust Pr. 820, Pr. 821. (Refer to page
5-35).
(3)-3 Perform speed feed forward/model
adaptive speed control.
tion 5.1.11).
(1)-2 Decrease Pr. 820 and increase Pr. 821.
(1)-3 Perform speed feed foward control and
model adaptive speed control.
tion 6.4.5.)
(3) Check the wiring.
Basic settings