B-65302EN/01 SPECIFICATIONS FOR THE βiS SERIES 3.SELECTING A MOTOR
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3.2.4.2 Calculating the torque required by the motor shaft in
acceleration
To obtain the torque required by the motor shaft (T), add the constant
load torque (T
m
) to the acceleration torque (T
a
).
ma TTT +=
T : Torque required by the motor axis
T
a
: Acceleration torque
T
m
: Constant load torque
[Example of calculation for condition 4-2] Acceleration torque
When T
m
is 1.4 [N⋅m] as calculated in example of calculation <1> and
T
a
is 14.6 [N⋅m] as calculated in example of calculation <4>-1, the
acceleration torque (T) is calculated as follows:
T = 14.6 [N⋅m] + 1.4 [N⋅m] = 16.0 [N⋅m]
The speed when the maximum torque is required (V
r
) is 2050 [min
-1
].
The speed-torque characteristics of the β8/3000is, given below, show
that the point of 16.0 [N⋅m]/2050 [min
-1
] is beyond the intermittent
operating zone of the β8/3000is (the torque is insufficient).
Speed - torque characteristics
0
2
4
6
8
10
12
14
16
0 1000 2000 3000
Speed (min
-1
)
Torque (N
⋅
⋅
⋅
⋅
m)
16.0[N⋅
⋅⋅
⋅m]
/ 2050[min
-1
]
Speed - torque characteristics for
β
ββ
β8/3000iS
If it is impossible to change the operation specifications of the shaft
(such as to increase the acceleration time), a larger motor must be
selected.
Select the β12/3000is (motor inertia (J
M
) = 0.00228 [kg⋅m
2
], 1.5 times
load inertia ratio) and calculate the acceleration torque again.
T
a
= 17.9 [N⋅m] = 182.5 [kgf⋅cm]
V
r
= 2050 [min
-1
]
T = 17.9 [N⋅m] + 1.4 [N⋅m] = 19.3 [N⋅m]