Omron EasySpeed 3G3JE, Руководство пользователя

Страница: 127 / 133

Chapter 7
7-9
Appendix
7-2 Precautions on Using the Inverter for a Motor
■
Using Inverter for Existing Standard
Motor
When a standard motor is operated with the Inverter, a
power loss is lightly higher than when operated with a
commercial power supply. In addition, cooling effects also
decline the low-speed range, resulting in an increase in
the motor temperature. Therefore, motor torque must be
reduced in the low speed range.
The following figure shows allowable load characteristics
of a standard motor.
● High-speed Operation
When using the motor at high-speed (60 Hz or more),
problems may arise in dynamic balance and bearing
durability.
● Torque Characteristics
The motor may require more acceleration torque when the motor is operated with the Inverter than
when operated 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.
●
Vibration
The 3G3JE Series employs high carrier PWM control to reduce motor vibration. When the motor is
operated with the Inverter, motor vibration is almost the same as when operated with a commercial
power supply.
Motor vibration may, however, become greater in the following cases.
• 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.
• Residual imbalance in the rotor
Take special care when the motor is operated at a high speed (60 Hz or more).
● Noise
Noise is almost the same as when the motor is operated with a commercial power supply. Motor
noise, however, becomes louder when the motor is operated at a speed higher than the rated speed
(60 Hz).
100
90
80
70
60
50
0 3 10 20 60
Torque (%)
Continuous
Frequency (Hz)
25% ED (or 15 min)
40% ED (or 20 min)
60% ED (or 40 min)
Allowable Load Characteristics
of Standard Motor