Mitsubishi FR-A800

Check first when you have a trouble
670
PROTECTIVE FUNCTIONS
6.6.12 Speed does not accelerate
Check
points
Possible cause Countermeasure
Refer to
page
Input
signal
Start command and frequency command are
chattering.
Check if the start command and the frequency command are
correct.

The wiring length used for analog frequency
command is too long, and it is causing a
voltage (current) drop.
Perform Analog input bias/gain calibration. 415
The input signal lines are affected by external
EMI.
Take countermeasures against EMI, such as using shielded
wires for input signal lines.
84
Parameter
Setting
Pr.1 Maximum frequency, Pr.2 Minimum
frequency, Pr.18 High speed maximum
frequency, and calibration parameter C2 to
C7 settings are improper.
Check the settings of Pr.1 and Pr.2 and set Pr.18. 345
Check the calibration parameter C2 to C7 settings. 415
The maximum voltage (current) input value is
not set during the External operation. (Pr.125,
Pr.126, Pr.18)
Check the settings of Pr.125 Terminal 2 frequency setting
gain frequency and Pr.126 Terminal 4 frequency setting
gain frequency.
To operate at 120 Hz or higher, set Pr.18 High speed
maximum frequency.
345, 415
Torque boost (Pr.0, Pr.46, Pr.112) setting is
improper under V/F control, so the stall
prevention function is activated.
Increase/decrease the Pr.0 Torque boost setting value by
0.5% increments so that stall prevention does not occur.
597
V/F pattern is improper when V/F control is
performed.
(Pr.3, Pr.14, Pr.19)
Set rated frequency of the motor to Pr.3 Base frequency.
Use Pr.19 Base frequency voltage to set the base voltage (for
example, rated motor voltage).
598
Change Pr.14 Load pattern selection according to the load
characteristic.
600
Stall prevention (torque limit) function is
activated due to a heavy load.
Reduce the load weight. 
Set Pr.22 Stall prevention operation level (torque limit level)
higher according to the load. (If Pr.22 is set too high, an
overcurrent trip (E.OC[]) is likely to occur.)
185, 348
Check the capacities of the inverter and the motor. 
Auto tuning is not performed under Advanced
magnetic flux vector control, Real sensorless
vector control, or vector control.
Perform offline auto tuning. 442
The setting of pulse train input is improper.
Check the specification of the pulse generator (open collector
output or complementary output) and check the adjustment of
the pulse train and frequency (Pr.385 Frequency for zero
input pulse and Pr.386 Frequency for maximum input
pulse).
324
During PID control, output frequency is automatically controlled to make measured value = set point. 501
Main
Circuit
Brake resistor is connected across terminals
P/+ and P1 or across P1 and PR by mistake.
Connect an optional brake resistor (FR-ABR) across terminals
P/+ and PR.
71