Delta Electronics VFD-M Series, User Manual

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Appendix CHow to Select the Right AC Motor Drive
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Revision May 2008, ME14, SW V3.04 C-5
decelerate within a certain time with high load inertia that can’t be handled by the AC
Motor Drive in the required time, either use an external brake resistor and/or brake unit,
depending on the model, (to shorten deceleration time only) or increase the capacity for
both the motor and the AC Motor Drive.
C.3 How to Choose a Suitable Motor
Standard motor
When using the AC Motor Drive to operate a standard 3-phase induction motor, take the
following precautions:
1
、
The energy loss is greater than for an inverter duty motor.
2
、
Avoid running motor at low speed for a long time. Under this condition, the motor
temperature may rise above the motor rating due to limited airflow produced by the
motor’s fan. Consider external forced motor cooling.
3
、
When the standard motor operates at low speed for long time, the output load must be
decreased.
4
、
The load tolerance of a standard motor is as follows:
3 6 20 60
100
82
70
60
50
0
60%
40%
25%
to
rq
ue(
%
)
continuous
Frequency (Hz)
Load duty-cycle
5
、
If 100% continuous torque is required at low speed, it may be necessary to use a
special inverter duty motor.
6
、
Motor dynamic balance and rotor endurance should be considered once the operating
speed exceeds the rated speed (60Hz) of a standard motor.