Fuji Electric FRENIC-Ace series - Page 591

10.3 Equations for Selections
10-9
SELECTING OPTIMAL MOTOR AND INVERTER CAPACITIES
Chap 10
(2) For a general rotating body
Table 10.3-1 lists the calculation equations of moment of inertia of various rotating bodies including the above
cylindrical rotating body.
Table 10.3-1 Moment of Inertia of Various Rotating Bodies
Shape
Mass: W (kg)
Shape
Mass: W (kg)
Moment of inertia:
J (kg·m
2
)
Moment of inertia:
J (kg·m
2
)
Hollow cylinder
ρ
π
= ••• − L)DD(
4
W
2
2
2
1
ρ= ••• LBAW
)DD(W
8
1
J
2
2
2
1
+= ••
)A+L(W
12
1
=J
22
a
••
)A
4
1
+L(W
12
1
=J
22
b
•••
)L
3
1
LLL(WJ
2
0
2
0c
•••
++≈
Sphere
ρ
π
= ••
3
D
6
W
2
DW
10
1
=J
••
Cone
ρ
π
= ••• LD
12
W
2
ρ
π
=
•••
LD
4
W
2
2
DW
40
3
J
•• =
)D
4
3
+L(W
12
1
=J
22
a
•••
)D
16
3
+L(W
3
1
=J
22
b
•••
)L
3
1
LLL(WJ
2
0
2
0c
•••
++≈
Rectangular prism
ρ= ••• LBAW
)BA(W
12
1
J
22
+=
••
Square cone (Pyramid,
rectangular base)
ρLBA
3
1
=W
••••
ρ=
••••
LBA
3
1
W
)B+A(W
20
1
=J
22
••
)A
4
1
+L(W
10
1
=J
22
b
•••
)L
5
3
LL
2
3
L(WJ
2
0
2
0c
•••• ++≈
Triangular prism
ρ= ••• LA
4
3
W
2
2
AW
3
1
=J
••
ρ
π
= ••• LD
12
W
2
Tetrahedron with an
equilateral triangular
base
ρ= •••
LA
12
3
W
2
)D
8
3
+L(W
10
1
=J
22
b
•••
)L
5
3
LL
2
3
L(WJ
2
0
2
0c
•••• ++≈
2
AW
5
1
=J
••
Main metal density (at 20°C) ρ(kg/m
3
) Iron: 7860, Copper: 8940, Aluminum: 2700