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Appendix
7-1
Selecting the Inverter
7-1-1 Selecting the Motor Capacity
Before selecting the Inverter, select the motor. To select the proper motor, calculate the load inertia
according to the application, and calculate the motor's required capacity and torque.
Simple Selection Method: Required Output Calculation
■
With this method, the motor is selected based on the output (kW) required for the motor's normal
steady-state operation. More advanced calculations, such as the accelerating/decelerating opera-
tion, are omitted, so some extra capacity is added to the calculation result. This simple selection
method can be used for applications such as fans and conveyor machinery, in which the motor oper-
ates continuously in a steady state.
Note The simple selection method cannot be used for the following kinds of applications. In these
cases, used the detailed selection method.
• Applications requiring quick starts (acceleration)
• Applications with frequent starts and stops
• Applications with high inertia in the power transmission
• Applications with low efficiency in the power transmission
●
Direct Drive Application: Normal Power P0 (kW)
µ : Coefficient of friction
M: Weight of linear drive mechanism (kg)
g: Acceleration of gravity (g ≈ 9.8 m/s
Vl: Velocity of linear drive mechanism (m/min)
η : Efficiency of transmission mechanism ( η ≤ 1)
Note This equation can be also be used for belt conveyors.
7-2
M
P
(kW) =
0
µ
Motor
η
Vl
2
)
µ·Mg·V
l
−3
× 10
60·η
Chapter 7
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