Mitsubishi Electric FR-A800, Instruction Manual

Page: 930 / 1042

Check first when you have a trouble Protective functions
6 - 42
6.6.8 Speed varies during operation
Under Advanced magnetic flux vector control, Real sensorless vector control, vector control, and en-
coder feedback control, the output frequency varies between 0 and 2 Hz as the load fluctuates. This
is a normal operation and not a fault.
Check
points
Possible cause Countermeasure
Refer to
page
Load Load varies during an operation.
Select Advanced magnetic flux vector control,
Real sensorless vector control, vector control, or
encoder feedback control.
5-56, 5-692
Input
signal
Frequency setting signal is varying. Check the frequency setting signal.
⎯
The frequency setting signal is affected by
EMI.
Set filter to the analog input terminal using
Pr. 74 "Input filter time constant", Pr. 822 "Speed
setting filter 1".
5-399
Take countermeasures against EMI, such as
using shielded wires for input signal lines.
3-1
Malfunction is occurring due to the
undesirable current generated when the
transistor output unit is connected. Use terminal PC (terminal SD when source
logic) as a common terminal to prevent a
malfunction caused by undesirable current.
2-41
Multi-speed command signal is chattering. Take countermeasures to suppress chattering.
⎯
Feedback signal from the encoder is
affected by EMI.
Place the encoder cable far from the EMI source
such as main circuit and power supply voltage.
Earth (ground) the shield of the encoder cable
to the enclosure using a metal P-clip or U-clip.
2-67
Parameter
Setting
Fluctuation of power supply voltage is too
large.
Under V/F control, change the Pr. 19 "Base
frequency voltage" setting (approximately by
3%).
5-654
Pr. 80 "Motor capacity" and Pr. 81 "Number
of motor poles" are not appropriate for the
motor capacity under Advanced magnetic
flux vector control, Real sensorless vector
control, vector control, or PM sensorless
vector control.
Check the settings of Pr. 80 and Pr. 81. 5-56
Wiring length exceeds 30 m when
Advanced magnetic flux vector control, Real
sensorless vector control, vector control, or
PM sensorless vector control is selected.
Perform offline auto tuning. 5-67
Under V/F control, wiring is too long and a
voltage drop occurs.
In the low-speed range, set 0.5% in Pr. 0 "Torque
boost".
5-652
Change the control method to Advanced
magnetic flux vector control or Real sensorless
vector control.
5-56
Hunting occurs by the generated vibration,
for example, when structural rigidity at load
side is insufficient.
Disable automatic control functions, such as the
energy saving operation, fast-response current
limit operation, torque limit, regeneration
avoidance function, Advanced magnetic flux
vector control, Real sensorless vector control,
vector control, encoder feedback control, droop
control, stall prevention, online auto tuning,
notch filter, and orientation control.
Under PID control, set smaller values to Pr. 129
"PID proportional band" and Pr. 130 "PID
integral time".
Adjust so that the control gain decreases and
the level of safety increases.
⎯
Change Pr. 72 "PWM frequency selection"
setting.
5-219