Yaskawa G5HHP Drive - Manual (Page 351)

12.1 Inverter Application Precautions
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12.2 Motor Application Precautions
12.2.1 Using the Inverter for an Existing Standard Motor
When a standard motor is operated with the Inverter, power loss is slightly higher than when operated with
a commercial power supply. In addition, cooling effects also diminish in the low-speed range, resulting in an
increase in the motor temperature. Therefore, the motor torque should be reduced in the low-speed range.
The following graph shows the allowable load characteristics of a standard motor.
If 100% torque is continuously required in the low-speed range, use a special motor for use with inverters.
Frequency (Hz)
60 20 3
0
100
82
70
60
50
Torque
(%)
Continuous
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60% ED (or 40 minutes)
40% ED (or 20 minutes)
25% ED (or 15 minutes)
If the input voltage is high (440 V or higher) or the wiring distance is long, the motor insulation voltage must
be considered. Contact your Yaskawa representative for details.
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High-speed Operation
When using the motor at a high speed (60 Hz or more), problems may arise in dynamic balance and bearing
durability. Contact the motor manufacturer for details.
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Torque Characteristics
The motor may require more acceleration torque when the motor is operated with the Inverter than when oper-
ated with a commercial power supply. Check the load torque characteristics of the machine to be used with
the motor to set a proper V/f pattern.
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Vibration
Resonance with the Natural Frequency of the Mechanical System
Take special care when a machine that has been operated at a constant speed is to be operated in variable speed
mode.
If resonance occurs, install vibration-proof rubber on the motor base or use the frequency jump function to
skip any frequency resonating the machine.
Imbalanced Rotor
Take special care when the motor is operated at a higher speed (60 Hz or more).
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Noise
Noise is almost the same as when the motor is operated with a commercial power supply. Motor noise, howev-
er, becomes louder when the motor is operated at a speed higher than the rated speed (60 Hz).
12.2.2 Power Transmission Mechanism (Speed Reducers, Belts, and Chains)
If an oil-lubricated gearbox or speed reducer is used in the power transmission mechanism, oil lubrication will
be affected when the motor operates only in the low speed range. The power transmission mechanism will
make noise and experience problems with service life and durability if the motor is operated at a speed higher
than 60 Hz.
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