
B-65262EN/03 SPECIFICATIONS FOR THE αiS/αi SERIES 3.SELECTING A MOTOR
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[Example of calculation for condition 5]
Root-mean-square value of the torques
Example)
α30/4000i
S ( T
s
= 3.0[N⋅m] = 306[kgf⋅cm] ), T
a
= 83.2[N⋅m],
T
m
= T
o
= 3.0[N⋅m], t
1
= 0.08[sec], t
2
= 2.0[sec], t
3
= 3.0[sec]
() ()
30.220.08
30.30.083.0-83.22.00.30.080.32.83
2
2
2
2
++×
×+×+×+×+
=
rmsT
= 15.0[N⋅m] < T
s
× 0.9 = 30 × 0.9 = 27[N⋅m]
The α30/4000is can be used for operation.
Root-mean-square value of torque in a cycle in which the load varies
If the load conditions (cutting load, acceleration/deceleration
conditions, etc.) vary widely in a single cycle, write a time-torque
graph according to the operation cycle, as in above item. Obtain the
root-mean-square value of the torques and check that the value is
smaller than or equal to the torque at stall.
0
332211
2
...
222
t
tTtTtTtT
T
nn
rms
++++
=
t
0
= t
1
+ t
2
+ t
3
+. . . + t
n
NOTE
The motor actually rotates, but the determination
must be based on the stall torque.
When the motor is being operated at high speed for
a comparatively large proportion of the time, you
must take the rotating speed of the motor into
consideration and evaluate whether output can be
specified in terms of a continuous operation torque.