
3.SELECTING A MOTOR SPECIFICATIONS FOR THE βiS SERIES B-65302EN/01
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[Example of calculation for condition 5]
Root-mean-square value of the torques
β12/3000is ( T
s
= 1.4 [N⋅m] ), T
a
= 17.9 [N⋅m],
T
m
= T
o
= 1.4 [N⋅m], t
1
= 0.1 [sec], t
2
= 2.0 [sec], t
3
= 3.0 [sec]
() ()
3.00.220.1
3.04.10.11.4-17.92.04.10.1
2
2
2
2
4.19.17
++×
×+×+×+×
=
+
rmsT
= 3.8 [N⋅m] = 38.8 [kgf⋅cm] < T
s
× 0.9 = 11 × 0.9 = 9.9 [N⋅m]
= 101.0 [kgf⋅cm]
The β12/3000is 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.