Omron EasySpeed 3G3JE, User Manual

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Chapter 7
7-7
Appendix
Calculating the Combined Torque and Effective Torque
• Effective torque T
RMS
(N·m)
• Maximum torque T
MAX
(N·m) = T1 = TA + T
L
● Selecting the Motor
Select the motor capacity by putting the results of the calculations above into the following equations.
Calculate the motor capacities from the following two equations and use the larger of the two results
as the motor capacity. Furthermore, when selecting the motor, add at least 20% to the motor capac-
ity result to allow for calculation error and errors due to model changes.
Motor Capacity Equivalent to Effective Torque
Motor Capacity Required to Output the Maximum Torque
Note The motor's maximum torque is calculated as 150% of the rated torque.
Time
(r/min)
Time
(N·m)
0
Time
0
Time
0
Speed
(N·m)
(N·m)
Load torque
Combined torque
t1
T
A
T
L
T1
T2
T3
T4
t2 t3 t4
1 cycle
N
Acceleration/ deceleration torque
Σ
(T
i
2
·t
i
)
Σ
ti
=
T1
2
·t1 + T2
2
·t2 + T3
2
·t3 + T4
2
·t4
t1 + t2 + t3 + t4
=
2
π
·T
RMS
·N
60
N: Max. speed (r/min)
Motor capacity (kW) =
×
10
−
3
2
π
·T
MAX
·N
60
×
1.5
N: Max. speed (r/min)
Motor capacity (kW) =
×
10
−
3