YASKAWA CIMR-MC5A20P4 Instruction Manual page 257

for use with Inverters). It will also help to some extent to lower the Inverter's carrier frequency (constant
C6-01).
In addition, remember that the leakage current increases as the cable is lengthened.
9.2.12 If There is Mechanical Oscillation
The machinery is making unusual sounds.
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1. There may be resonance between the mechanical system's characteristic frequency and
the carrier frequency.
If the motor is running with no problems and the machinery is oscillating with a high-pitched whine, it
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may indicate that this is occurring. To prevent this type of resonance, adjust the carrier frequency with
constants C6-01 to C6-03.
2. There may be resonance between a machine's characteristic frequency and the output fre-
quency of the Inverter.
To prevent this from occurring, either use the jump frequency functions in constants d3-01 to d3-04 or
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install rubber padding on the motor base to reduce oscillation.
J Oscillation and hunting are occurring with open-loop vector control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting constants
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C4-02 (torque compensation time constant), C8-08 (AFR gain), and C3-02 (slip compensation primary
delay time) in order. Lower the gain setting and raise the primary delay time setting.
Vector control is not effective without autotuning. Perform autotuning for motor unit separately.
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Oscillation and hunting are occurring with flux vector control.
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The gain adjustment may be insufficient. Adjust the various types of speed control loop (ASR) gain. (For
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details, refer to page - 34.)
If the mechanical system's resonance point coincides with the Inverter's operating frequency and the os-
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cillation cannot be eliminated in this way, increase the ASR primary delay time (constant C5-06) and then
try adjusting the gain again.
Vector control is not effective without autotuning. Perform autotuning for motor unit separately.
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Autotuning not performed during vector control.
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Vector control is not effective without autotuning. Perform autotuning for motor unit separately, or set
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control method selection (A1- -02) to V/f control.
9.2.13 If the Motor Rotates Even When Inverter Output is Stopped
The DC injection braking is insufficient. If the motor continues operating at low speed, without com-
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pletely 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 time at stop) setting.
9.2.14 If 0 V is Detected When the Fan is Started, or Fan Stalls
Generation of 0 V and stalling can occur if the fan is turning when it is started. The DC injection braking
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is insufficient when starting.
This can be prevented by slowing fan rotation by DC injection braking before starting the fan. Increase
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the constant b2-03 (DC injection braking time at start) setting.
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9.2 Troubleshooting
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