Omron VARISPEED G7 -, Instruction Manual

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7
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Oscillation and hunting are occurring with flux vector control.
The gain adjustment is insufficient. Adjust the various gains for speed control (ASR). If the oscillation points
overlap with those of the machine and cannot be eliminated, increase the primary delay time constant for
speed control (ASR) in C5-06 and then readjust the gains.
If autotuning is not performed, proper performance cannot be achieved for vector control. Perform autotuning
or set the motor constants according to calculations.
Oscillation and hunting are occurring with PID control.
If there is oscillation or hunting during PID control, check the oscillation cycle and individually adjust P, I,
and D constants. (Refer to page 6-97.)
Autotuning has not been performed with vector control.
Vector control will not perform if autotuning has not been performed. Perform autotuning separately for the
motor, or set the motor constants through calculations. Alternatively, change the Control Method Selection
(A1-02) to V/f control.
If the Motor Rotates Even When Inverter Output is Stopped
If the motor rotates even when the Inverter output is stopped, the DC injection braking is insufficient. If the
motor continues operating at low speed, without completely stopping, and after a deceleration stop has been
executed, it means that the DC injection braking is not decelerating enough. Adjust the DC injection braking
as follows:
•
Increase the constant b2-02 (DC Injection Braking Current) setting.
•
Increase the constant b2-04 (DC Injection Braking (initial excitation) Time at Stop) setting.
If 0 V is Detected When the Fan is Started, or Fan Stalls
Generation of 0 V (main circuit voltage) and stalling can occur if the fan is turning when it is started. The DC
injection braking is insufficient when starting.
This can be prevented by slowing fan rotation by DC injection braking before starting the fan. Increase the
constant b2-03 (DC injection braking time (initial excitation) at start) setting.
If Output Frequency Does Not Rise to Frequency Reference
Use the following information if the output frequency does not rise to the frequency reference.
The frequency reference is within the jump frequency range.
When the jump frequency function is used, the output frequency does not change within the jump frequency
range. Check to be sure that the Jump Frequency (constants d3-01 to d3-03) and Jump Frequency Width (con-
stant d3-04) settings are suitable.