C.1 capacity formulas – Delta Electronics AC Motor Drive VFD-EL User Manual
Page 203
Appendix C How to Select the Right AC Motor Drive|
C-2
Revision August 2008, 2ELE, V1.02
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
Ч
≤
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
Ч
+
Ч
Ч
Ч
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
Ч
≤
+
=
+
Ч
Ч
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
−
−
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
≤
+
=
+
Ч
Ч
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
−
−
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
≤
+
+
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛
−