Troubleshooting In The Speed Control - Mitsubishi Electric 800 Series Instruction Manual (Function

5.9

Troubleshooting in the speed control

PM PM PM
Sensorless Sensorless Vector Sensorless Vector Vector
No. Condition
Motor wiring is incorrect.
Encoder type selection
switch (Vector control
compatible option) is
The motor does not incorrect.
1 rotate. (Vector
control)
The wiring of the
encoder is incorrect.
The parameter setting
and the number of
encoder pulses used are
different.
Encoder power
specifications are
incorrect. Alternatively,
power is not input.
Speed command from
the controller is different
from the actual speed.
The speed command is
affected by noise.
The setting for the
Motor does not run at
number of encoder
the correct speed.
pulses is incorrect.
2 (Command speed
The command speed
and actual speed
and the speed
differ.)
recognized by the
inverter are different.
The motor constant
varies due to increase in
the motor temperature.
Torque shortage.
The torque limit is
The speed does not
operating.
3 accelerate to the
command speed.
Only P (proportional)
control is performed.
Possible cause
• Check the wiring.
Select V/F control (set "9999" in Pr.80 Motor capacity or Pr.81 Number of
motor poles, and "40" in Pr.800 Control method selection) and check the
motor rotation direction.
When the SF-V5RU (1500 r/min series) motor is used, set Pr.19 Base frequency
voltage to 170 V (340 V) for the 3.7 kW motor or lower, and to 160 V (320 V) for
the motor whose capacity is higher than 3.7 kW, and set Pr.3 Base frequency to
50 Hz.
• When a forward signal is input, rotation in the counterclockwise direction as
viewed from the motor shaft direction is correct. (If the motor rotates clockwise,
the phase sequence of the inverter secondary side wiring is incorrect.)
• Check the encoder specifications.
Check the encoder type selection switch of differential/complementary (Vector
control compatible option).
• When using the system where the motor shaft can be rotated by an external force
other than the motor without any safety troubles at Vector control setting, rotate
the motor counterclockwise and check if FWD is indicated.
If REV is indicated, the phase sequence of the encoder is incorrect.
Check the wiring, and set Pr.359 Encoder rotation direction in accordance with
the motor specification. (Refer to
If the clockwise direction is forward as viewed from the motor shaft side, set
Pr.359 = "100".
If the counterclockwise direction is forward as viewed from the motor shaft side,
set Pr.359 = "101".
• If the parameter setting value is lower than the number of encoder pulses used,
the motor does not rotate. Set Pr.369 Number of encoder pulses correctly.
(Refer to
• Check the encoder power specifications (5 V/12 V/15 V/24 V), and input the
external power supply.
When the encoder output is the differential line driver type, only 5 V can be input.
Make the voltage of the external power supply the same as the encoder output
voltage, and connect the external power supply between PG and SD.
• Check that the speed command sent from the controller is correct. (Take EMC
measures.)
• Lower the setting of Pr.72 PWM frequency selection.
• Check the Pr.369 setting (under Vector control). (Refer to
• Adjust the bias and gain (Pr.125, Pr.126, C2 (Pr.902) to C7 (Pr.905)) of the
speed command again.
Enable the online auto tuning at startup (set Pr.95 (Pr.574) = "1") (under Real
sensorless vector control). (Refer to
To perform the online auto tuning at startup for a lift, use a brake sequence function
for the brake opening timing at a start.
• Raise the torque limit.
(Refer to the torque limit for speed control on
• Increase the capacity.
• Speed deviation occurs under P (proportional) control when the load is heavy.
Select PI control.
Countermeasure
page 405.)
page 405.)
page 402.)
5.9 Troubleshooting in the speed control
page 405.)
page 122.)
5. Speed Control
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