Speed Varies During Operation; Operation Mode Is Not Changed Properly - Mitsubishi Electric FR-CS82S-025 Instruction Manual

6.6.7

Speed varies during operation

Check Possible cause
point
The load varies during an operation.
Load
The frequency setting signal is varying.
The frequency setting signal is affected by
EMI.
Input
signal
A malfunction is occurring due to the
undesirable current generated when the
transistor output unit is connected.
A multi-speed command signal is
chattering.
Fluctuation of power supply voltage is too
large.
Wiring length exceeds 30 m when
General-purpose magnetic flux vector
control is performed.
Under V/F control, wiring is too long and a
voltage drop occurs.
Parameter
setting
Hunting occurs by the generated
vibration, for example, when structural
rigidity of the load is insufficient.
6.6.8

Operation mode is not changed properly

Check Possible cause
point
Input
The start signal (STF or STR) is ON.
signal
The Pr.79 Operation mode selection
setting is not appropriate.
Parameter
setting
Operation mode and a writing device do
not correspond.
224
6. PROTECTIVE FUNCTIONS
6.6 Check first when you have a trouble
Countermeasure
Select General-purpose magnetic flux vector control.
Check the frequency setting 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.
Take countermeasures to suppress chattering.
Under V/F control, change the Pr.19 Base frequency voltage setting
(approximately by 3%).
Perform offline auto tuning
Adjust the Pr.0 Torque boost setting by increasing with 0.5%
increments for the low-speed operation.
Change to General-purpose magnetic flux vector control.
Disable automatic control functions, such as fast-response current
limit function, regeneration avoidance function, and General-purpose
magnetic flux vector control.
For PID control, set smaller values to Pr.129 PID proportional band
and Pr.130 PID integral time.
Lower the control gain to increase the stability.
Change the Pr.72 PWM frequency selection setting.
Countermeasure
Check that the STF and STR signals are OFF.
When either is ON, the operation mode cannot be changed.
When Pr.79 setting is "0 (initial value)", the inverter is placed in the
External operation mode at input power ON and can be switched to
the PU operation mode. At other settings (1 to 4), the operation mode
is limited accordingly.
Check Pr.79 Operation mode selection, Pr.338 Communication
operation command source, Pr.339 Communication speed
command source, and Pr.551 PU mode operation command source
selection, and select an operation mode suitable for the purpose.
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