Delta Electronics VFD-M Series, User Manual

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Appendix CHow to Select the Right AC Motor Drive
|
C-2 Revision May 2008, ME14, SW V3.04
C.1 Capacity Formulas
1. When one AC motor drive operates one motor
The starting capacity should be less than 1.5x rated capacity of AC motor drive
The starting capacity=
) ( _ _ _ _ _ 5 . 1
375 cos 973
2
kVA drive motor AC of capacity the
t
N GD
T
N k
A
L
× ≤
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
× +
× ×
×
ϕ η
2. When one AC motor drive operates more than one motor
2.1 The starting capacity should be less than the rated capacity of AC motor drive
„ Acceleration time ≦ 60 seconds
The starting capacity=
( ) [ ] ( )
) ( _ _ _ _ _ 5 . 1 1
cos
1 1 1
kVA drive motor AC of capacity the k
n
n
P k n n
N k
s C s s
T
s
T
× ≤ + = +
×
×
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
− −
ϕ η
„
Acceleration time
≧
60 seconds
The starting capacity=
( )
[ ]
( )
) ( _ _ _ _ _ 1
cos
1 1 1
kVA drive motor AC of capacity the k
n
n
P k n n
N k
s C s s
T
s
T
≤ + = +
×
×
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
− −
ϕ η
2.2 The current should be less than the rated current of AC motor drive(A)
„
Acceleration time
≦
60 seconds
) ( _ _ _ _ _ _ 5 . 1 1 1 A drive motor AC of current rated the k
n
n
I n
S M
T
S
T
× ≤ + +
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛
−
„ Acceleration time ≧ 60 seconds
) ( _ _ _ _ _ _ 1 1 A drive motor AC of current rated the k
n
n
I n
S M
T
S
T
≤ + +
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛
−