252
Check first when you have a trouble
5.5.7 Acceleration/deceleration is not smooth
5.5.8 Speed varies during operation
Check
points
Possible Cause Countermeasures
Refer
to
page
Parameter
Setting
Acceleration/deceleration time is too short. Increase acceleration/deceleration time. 87
Stall prevention function is activated due to a heavy
load.
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).)
74
Check the capacities of the drive unit and the motor. —
Regeneration avoidance operation is performed
If the speed becomes unstable during regeneration
avoidance operation, decrease the setting of Pr. 886
Regeneration avoidance voltage gain.
211
Others
The machine is unstable, or the load fluctuates.
Adjust machine/equipment so that there is no
mechanical looseness. Eliminate the load fluctuation.
Use Pr. 156 Stall prevention operation selection to disable
stall prevention operation.
74
Check
points
Possible Cause Countermeasures
Refer
to
page
Input
signal
The speed setting signal is affected by EMI.
Set filter to the analog input terminal using Pr. 74 Input
filter time constant.
134
Take countermeasures against EMI, such as using
shielded wires for input signal lines.
36
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.
21
Multi-speed command signal is chattering. Take countermeasures to suppress chattering. —
Parameter
Setting
Hunting occurs by the generated vibration, for example,
when structural rigidity at load side is insufficient.
Disable automatic control functions, such as
regeneration avoidance function and stall prevention.
During the PID control, set smaller values to Pr. 129 PID
proportional band and Pr. 130 PID integral time.
During the PID control, set smaller values to Pr. 129 PID
proportional band and Pr. 130 PID integral time.
Lower the control gain, and adjust to increase the
stability.
—
