Delta 1.07 VFD-D D - Manual (Page 135)

Appendix B How to Select AC Motor Drive |DD Series
B-1
Appendix B
How to Select AC Motor Drive
The choice of the right AC motor drive for the application is very important and has great influence on its
lifetime. If the capacity of AC motor drive is too large, it cannot offer complete protection to the motor
and motor maybe damaged. If the capacity of AC motor drive is too small, it cannot offer the required
performance and the AC motor drive maybe damaged due to overloading.
But by simply selecting the AC motor drive of the same capacity as the motor, user application
requirements cannot be met completely. Therefore, a designer should consider all the conditions,
including load type, load speed, load characteristic, operation method, rated output, rated speed, power
and the change of load capacity. The following table lists the factors you need to consider, depending
on your requirements.
Related Specification
Item
Speed and
torque
characteristics
Time
ratings
Overload
capacity
Starting
torque
Load type
Friction load and weight load
Liquid (viscous) load
Inertia load
Load with power transmission
● ●
Load speed
and torque
characteristics
Constant torque
Constant output
Decreasing torque
Decreasing output
● ●
Load
characteristics
Constant load
Shock load
Repetitive load
High starting torque
Low starting torque
● ● ● ●
Operation
Method
Continuous operation,
Short-time operation
Long-time operation at medium/low
speeds
● ●
Rated Output
Maximum output current
(instantaneous)
Constant output current
(continuous)
● ●
Rated Speed
Maximum frequency,
Base frequency
●
Input Power
Power supply transformer capacity
Percentage impedance
Voltage fluctuations and unbalance
Number of phases, single phase
protection
Frequency
● ●
Mechanical friction, losses in wiring ● ● Load Capacity
Changes
Duty cycle modification ●