电机学第一到四章自测题参考答案

（2）电磁功率Pem

Pem?P2?Pmec?Pad?PCu2?P2?Pmec?Pad?sNPem 所以 Pem?（3）转子铜损耗PCu2

PCu2=sNPem=0.05×103.3kW=5.3kW （4）输出转矩T2

P T2?2??NPN100?103?N?m?1005.2N?m nN9502?2?6060P2?Pmec?Pad100?0.7?0.3?kW?106.3kW

1?sN1?0.05（5）空载转矩T0

Pmec?Pad?0.7?0.3??103?N?m?10.05N?m T0?950?N2?60 （6）电磁转矩Tem

Tem?T2?T0??1005.2?10.05?N?m?1015.25N?m

3．一台三相笼型异步电动机，UN=380V，IN=35.5A，三角形联结。R1=0.7

''?0.4?,X2?3?,Rm?6?,Xm?75?。试用T形等效电路分析Ω，X1=1.7Ω,R2该电动机运行在s=0.04时是否过载。

解： Z1?R1?jX1??0.7?j1.7???1.84/67.64°Ω

'R2?0.4?'?jX2???j3???10.44/16.69°Ω Z?S?0.04?'2 Zm?Rm?jXm??6?j75???75.24/85.43°Ω 取定子额定相电压为参考相量，U1?380V，则定子相电流I1，为 I1?.??U1380380/0° ?A '75.24/85.43??rge??10.44/16.69?ZZ0.7?j1.7?75.24/85.43°×10.44/16.69° Z1?m2'6?j75?10?j3Zm?Z2. 17

?380/°0? 380/0380/0°A

0.7?j1.7?9.03?j3.967380/°0? 380° 380/0380/0A?A

9.73?j5.66711.26/30.220011.26/30.22° ? =33.75/-30.22°A 定子线电流为3?33.75A?58.45A，由于定子线电流远大于IN，故此时电动机处于过载状态。

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