Mitsubishi Electric FR-F800 Series Instruction Manual page 618

6.6.8
Under Advanced magnetic flux vector control, the output frequency varies between 0 and 2 Hz as the load fluctuates. This is
a normal operation and not a fault.
Check
point
Load The load varies during an operation.
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.
The Pr.80 Motor capacity and Pr.81
Number of motor poles settings are not
appropriate for the motor capacity under
Advanced magnetic flux vector control or
PM motor control.
Wiring length exceeds 30 m when
Advanced magnetic flux vector control or
PM motor control is performed.
Parameter
setting
Under V/F control, wiring is too long and a
voltage drop occurs.
Hunting occurs by the generated vibration,
for example, when structural rigidity of the
load is insufficient.
6.6.9
Check
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.
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Speed varies during operation
Possible cause
Operation mode is not changed properly
Possible cause
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Countermeasure
Select Advanced magnetic flux vector control.
Check the frequency setting signal.
Set filter to the analog input terminal using Pr.74 Input filter time
constant, Pr.822 Speed setting filter 1, etc.
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%).
Check the settings of Pr.80 and Pr.81.
Perform offline auto tuning
In the low-speed range, adjust the Pr.0 Torque boost setting by
0.5% increments.
Change the control method to Advanced magnetic flux vector
control.
Disable automatic control functions, such as energy saving
operation, fast-response current limit function, regeneration
avoidance function, Advanced magnetic flux vector control, stall
prevention, and online auto tuning.
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 the Pr.79 is set to "0 (initial value)", the operation mode is the
External operation mode at power ON. To switch to the PU
operation mode, press the
(press the key on the parameter unit (FR-PU07)). At other
settings (1 to 4, 6, 7), the operation mode is limited accordingly.
Check Pr.79 Operation mode selection, Pr.338 Communication
operation command source, Pr.339 Communication speed
command source, Pr.550 NET mode operation command
source selection and Pr.551 PU mode operation command
source selection, and select an operation mode suitable for the
purpose.
key on the operation panel
6. PROTECTIVE FUNCTIONS
6.6 Check first when you have a trouble
1
2
Refer to
page
177
3
—
355
4
93
65
5
—
552
6
177
7
383
8
551
177
9
—
10
218
Refer to
page
60, 563
240
240, 251
617