When One Ac Motor Drive Operates One Motor; When One Ac Motor Drive Operates More Than One Motor; When It Is Running Continuously; Appendix C How To Select The Right Ac Motor Drive - Delta Electronics AC Motor Drive VFD-G User Manual
Vfd-g series specific ac motor drives for plastic molding and air compressors machinery
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Appendix C How to Select the Right AC Motor Drive|
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=
⎛
×
k
N
⎜ ⎜
T
η
ϕ
×
×
973
cos
⎝
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
The starting capacity=
×
k
N
[
n
T
η
ϕ
×
cos
Acceleration time
The starting capacity=
×
k
N
[
n
T
η
ϕ
×
cos
2.2 The current should be less than the rated current of AC motor drive(A)
Acceleration time
⎡
+
+
n
I
1
M
⎢
T
⎣
Acceleration time
⎡
+
+
n
I
1
M
⎢
T
⎣
2.3 When it is running continuously
The requirement of load capacity should be less than the capacity of AC motor drive(kVA)
The requirement of load capacity=
×
k
P
M
≤
η
ϕ
×
cos
The motor capacity should be less than the capacity of AC motor drive
×
×
k
3
V
M
The current should be less than the rated current of AC motor drive(A)
×
≤
k
I
the
M
C-2
⎞
2
GD
N
⎟ ⎟
+
×
≤
×
1
5 .
L
375
t
⎠
A
≦
60 seconds
n
⎡
]
(
)
(
+
=
+
s
⎢
n
k
P
1
−
s
s
1
C
1
⎢
n
⎢
⎣
T
≧
60 seconds
n
⎡
]
(
)
(
+
=
+
s
⎢
n
k
P
1
−
s
s
1
C
1
⎢
n
⎢
⎣
T
≦
60 seconds
n
⎤
≤
×
k
1
1
5 .
the
⎛
⎞
S
−
⎜
S
⎟
⎥
n
⎝
⎠
⎦
T
60 seconds
≧
n
⎤
≤
k
1
the
_
rated
⎛
⎞
S
−
⎜
S
⎟
⎥
n
⎝
⎠
⎦
T
the
_
rated
_
capacity
−
×
×
3
≤
I
10
the
_
rated
M
_
rated
_
current
the
_
rated
_
capacity
⎤
)
≤
×
⎥
k
1
5 .
the
_
rated
−
s
1
⎥
⎥
⎦
⎤
)
≤
⎥
k
the
_
rated
_
capacity
−
s
1
⎥
⎥
⎦
_
rated
_
current
_
_
current
_
of
_
AC
_
of
_
AC
_
motor
_
_
capacity
_
of
_
AC
_
of
_
AC
_
motor
_
_
of
_
AC
_
motor
_
drive
_
capacity
_
of
_
AC
_
motor
_
of
_
AC
_
motor
of
_
AC
_
motor
_
drive
_
motor
_
drive
(
drive
(
kVA
)
_
motor
_
drive
(
kVA
)
drive
(
A
)
Revision July 2008, EG03, SW V1.06
(
kVA
)
_
drive
(
kVA
)
_
drive
(
kVA
)
(
A
)
A
)
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