Capacity Formulas; When One Ac Motor Drive Operates One Motor; When One Ac Motor Drive Operates More Than One Motor - Delta Electronics AC Motor Drive VFD-EL User Manual

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
η
× ×
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
The starting capacity=
×
k N
η
×
cos
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)
n
+
n
T
C-2
⎛ ⎞
2
GD N
⎜ ⎜ ⎟ ⎟
+ × ≤
T
ϕ
L
375 t
⎝ ⎠
A
Acceleration time ≦
⎡
[ ]
( )
+ =
⎢
n n k P 1
−
s s 1 C 1
T ⎢
ϕ
⎢
⎣
Acceleration time ≧
n
⎡
]
( )
+ = +
⎢
n k P 1
−
s s 1 C 1
⎢
n
⎢
⎣
Acceleration time
≦
n
⎡ ⎤
+ + ≤
I 1 k 1
⎛ ⎞
S
−
⎟
M ⎢ ⎜ S ⎥
n
T
⎝ ⎠
⎣ ⎦
T
Acceleration time
≧
n
⎡ ⎤
+ ≤
I 1 k 1 the
⎛ ⎞
S
−
⎢ ⎜ ⎟ ⎥
M S
n
⎝ ⎠
⎣ ⎦
T
×
1 5 . the _ capacity _
60 seconds
n
⎤
( )
+ s ≤ ×
⎥
k 1 5 . the
−
s 1
⎥
n
⎥
⎦
T
60 seconds
⎤
( )
s ≤
⎥
k the _ capacity
−
s 1
⎥
⎥
⎦
T
60 seconds
×
1 5 . the _ rated _ current
60 seconds
_ rated _ current
of _ AC _ motor _ drive
_ capacity _ of _ AC _
_ of _ AC _ motor
_ of _ AC _
_ of _ AC _ motor
Revision August 2008, 2ELE, V1.02
( kVA )
motor _ drive ( kVA )
_ drive ( kVA )
motor _ drive ( A )
_ drive ( A )