2、
电动机频繁启动
S
km
=S
rT
/(x
T
+S
rT
/S")=14 (MVA)
(1) 选用电机为37KW三相鼠笼异步电机(S
qM
=0.322 MVA)。
X
l
=(0.07+6.3/185)*0.5*0.15+(0.07+6.3/25)*0.05=0.031+0.016=0.047
S
q
=1/(1/S
qM
+X
l
/U
2
m
)=0.292
Q
fh
=0.302
u
qm
=(S
km
+Q
fh
)/(S
km
+Q
fh
+S
q
)=14.302/14.594=0.980
u
qM
=0.98*S
q
/S
qM
=0.98*0.292/0.322=0.89
(2) 选用电机为30KW三相鼠笼异步电机(S
qM
=0.263 MVA)。
X
l
=(0.07+6.3/185)*0.5*0.15+(0.07+6.3/16)*0.05=0.031+0.023=0.054
Q
fh
=0.302
S
q
=1/(1/S
qM
+X
l
/U2m)=0.239
u
qm
=(S
km
+Q
fh
)/(S
km
+Q
fh
+S
q
)=14.302/14.541=0.984
u
qM
=0.984*S
q
/S
qM
=0.984*0.239/0.263=0.90
故电机功率为30KW三相鼠笼异步电机可直接启动。
工厂配电设计手册150页表6-16，钢铁手册下册193页表23-4