Speed Varies During Operation; Operation Mode Is Not Changed Properly - Mitsubishi Electric FR-E720-0.1 K Instruction Manual

Check first when you have some troubles
5.5.8

Speed varies during operation

When Advanced magnetic flux vector control or the slip compensation is selected, the output frequency varies between 0 and
2Hz as load fluctuates. This is a normal operation and not a fault.
Check
points
Input
Multi-speed command signal is chattering.
signal
Load Load varies during an operation.
Frequency setting signal is varying.
The frequency setting signal is affected by EMI.
Input
signal
Malfunction is occurring due to the undesirable current
generated when the transistor output unit is connected.
Pr. 80 Motor capacity and Pr. 81 Number of motor poles
setting is improper for the capacities of the inverter and
the motor for Advanced magnetic flux vector control or
General-purpose magnetic flux vector control.
Fluctuation of power supply voltage is too large.
Parameter
Setting
Hunting occurs by the generated vibration, for example,
when structural rigidity at load side is insufficient.
Wiring length exceeds 30m when Advanced magnetic
flux vector control or General-purpose magnetic flux
vector control is performed.
Others
Wiring length is too long for V/F control, and a voltage
drop occurs.
5.5.9

Operation mode is not changed properly

Check
points
Input
Start signal (STF or STR) is ON.
signal
Pr. 79 setting is improper.
Parameter
Setting
Operation mode and a writing device do not
correspond.
294
Possible Cause
Possible Cause
Countermeasures
Take countermeasures to suppress chattering.
Select Advanced magnetic flux vector control or
General-purpose magnetic flux vector control.
Check the frequency reference signal.
Set filter to the analog input terminal using Pr. 74 Input
filter time constant.
Take countermeasures against EMI, such as using
shielded wires for input signal lines.
Use terminal PC (terminal SD when source logic) as a
common terminal to prevent a malfunction caused by
undesirable current.
Check the Pr. 80 Motor capacity and Pr. 81 Number of
motor poles setting.
Change the Pr. 19 Base frequency voltage setting (about
3%) under V/F control.
Disable automatic control functions, such as energy
saving operation, fast-response current limit function,
regeneration avoidance function, Advanced magnetic
flux vector control, General-purpose magnetic flux
vector control, and stall prevention.
Adjust so that the control gain decreases and the level of
safety increases.
Change Pr. 72 PWM frequency selection setting.
Perform offline auto tuning.
Adjust Pr. 0 Torque boost by increasing with 0.5%
increments for low-speed operation.
Change to Advanced magnetic flux vector control or
General-purpose magnetic flux vector control.
Countermeasures
Check that the STF and STR signals are OFF.
When either is ON, the operation mode cannot be
changed.
When Pr. 79 Operation mode selection setting is "0" (initial
value), the inverter is placed in the External operation mode
at input power ON. To switch to the PU operation mode,
press on the operation panel (press
parameter unit (FR-PU04/FR-PU07) is used) . At other
settings (1 to 4, 6, 7), the operation mode is limited
accordingly.
Check Pr. 79, Pr. 338, Pr. 339, Pr. 550, Pr. 551, and select
an operation mode suitable for the purpose.
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82
Refer
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186
when the
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