Appendix B How to Select AC Motor Drive |DD Series
B-2
B-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
375cos973
2
kVAdrivemotorACofcapacitythe
t
NGD
T
Nk
A
L
×≤
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
×+
××
×
ϕη
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=
()
[]
()
)(_____5.11
cos
111 kVAdrivemotorACofcapacitythek
n
n
Pknn
Nk
sCss
T
s
T
×≤+=+
×
×
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
−−
ϕη
Acceleration time
≧
60 seconds
The starting capacity=
()
[]
()
)(_____1
cos
111 kVAdrivemotorACofcapacitythek
n
n
Pknn
Nk
sCss
T
s
T
≤+=+
×
×
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
−−
ϕη
2.2 The current should be less than the rated current of AC motor drive(A)
Acceleration time
≦
60 seconds
)(______5.111 AdrivemotorACofcurrentratedthek
n
n
In
SM
T
S
T
×≤++
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛
−
Acceleration time
≧
60 seconds
)(______11 AdrivemotorACofcurrentratedthek
n
n
In SM
T
S
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=
)(_____
cos
kVAdrivemotorACofcapacitythe
Pk
M
≤
×
×
ϕη
The motor capacity should be less than the capacity of AC motor drive
)(_____103
3
kVAdrivemotorACofcapacitytheIVk MM ≤××××
−
The current should be less than the rated current of AC motor drive(A)
)(______ AdrivemotorACofcurrentratedtheIk M ≤×
