Speed Does Not Accelerate - Mitsubishi Electric FR-E700 Series Instruction Manual

Check first when you have troubles
7.6.12

Speed does not accelerate

Check Points
Input signal
Parameter
setting
Main circuit
7 - 30
Possible Cause
Start command and frequency command are
chattering.
The wiring length used for analog frequency
command is too long, and it is causing a volt-
age (current) drop.
Input signal lines are affected by external
EMI.
Pr. 1, Pr. 2, Pr. 18, calibration parameter C2 to
C7 settings are improper.
Torque boost (Pr. 0, Pr. 46) setting is
improper under V/F control, so the stall pre-
vention function is activated.
V/F pattern is improper when V/F control is
performed. (Pr. 3, Pr. 14, Pr. 19)
Stall prevention is activated due to a heavy
load.
Auto tuning is not performed under
Advanced magnetic flux vector control or
General-purpose magnetic flux vector con-
trol.
During PID control, output frequency is automatically controlled to make measured value =
set point.
Brake resistor is connected between terminal
P/+ and P1 or between terminal P1 and PR by
mistake.
Countermeasures
Check if the start command and the fre-
quency command are correct.
Perform analog input bias/gain calibration.
Take countermeasures against EMI, such as
using shielded wires for input signal lines.
Check the settings of Pr. 1 "Maximum fre-
quency" and Pr. 2 "Minimum frequency". If
you want to run the motor at 120Hz or
higher, set Pr. 18 "High speed maximum fre-
quency".
Check the calibration parameter C2 to C7 set-
tings.
Increase/decrease Pr. 0 "Torque boost" set-
ting value by 0.5% increments so that stall
prevention does not occur.
Set rated frequency of the motor to Pr. 3
"Base frequency". Use Pr. 19 "Base frequency
voltage" to set the base voltage (e.g. rated
motor voltage).
Change Pr. 14 "Load pattern selection"
according to the load characteristic.
Reduce the load weight.
Set Pr. 22 "Stall prevention operation level"
higher according to the load. (Setting Pr. 22
too large may result in frequent overcurrent
trip (E.OC ).)
Check the capacities of the inverter and the
motor.
Perform offline auto tuning.
Connect an optional brake transistor (MRS
type, FR-ABR) between terminal P/+ and PR.
Troubleshooting
Refer to
Page
—
6-181
3-47
6-50
6-181
6-33
6-54
6-56
—
6-42
—
6-88
6-277
3-34