Fuji Electric FRENIC-Ace series, Руководство пользователя

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10.2 Selection Procedure
10-4
(1) Calculating the load torque during constant speed running
(For detailed calculation, refer to Section 10.3.1 .)
It is essential to calculate the load torque during constant speed running for all loads.
First calculate the load torque of the motor during constant speed running and then select a tentative capacity so
that the continuous rated torque of the motor during constant speed running becomes higher than the load torque.
To perform capacity selection efficiently, it is necessary to match the rated speeds (base speeds) of the motor and
load. To do this, select an appropriate reduction-gear (mechanical transmission) ratio and the number of motor
poles.
If the acceleration or deceleration time is not restricted, the tentative capacity can apply as a defined capacity.
(2) Calculating the acceleration time (For detailed calculation, refer to Section 10.3.2 [ 2 ] .)
When there are some specified requirements for the acceleration time, calculate it according to the following
procedure:
1) Calculate the
moment of inertia for the load and motor
Calculate the moment of inertia for the load, referring to “10.3.2 Acceleration and deceleration time calculation.”
For the moment of inertia for motors, refer to the related motor catalogs.
2) Calculate the minimum acceleration torque (See Figure 10.2-2)
The acceleration torque is the difference between the motor short-time output torque (base frequency: 60 Hz)
explained in “10.1 (2) Maximum driving torque in a short time” and the load torque ( τ
L
/ η
G
) during constant
speed running calculated in the above (1) . Calculate the minimum acceleration torque for the whole range of
speed.
3) Calculate the acceleration time
Assign the value calculated above to the equation (Equation 10.3-15) in “10.3.2 Acceleration and deceleration
time calculation” to calculate the acceleration time. If the calculated acceleration time is longer than the
expected time, select the inverter and motor having one class larger capacity and calculate it again.
Figure 10.2-2 Example Study of Minimum Acceleration Torque