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一台单相变压器电压为220V/110V。当在高压侧加220V电压时,空载电流为I0,主磁通为。试问: (1)
一台单相变压器电压为220V/110V。当在高压侧加220V电压时,空载电流为I0,主磁通为
。试问: (1)若U2与u1连在一起,在U2-u2端加330V电压,此时空载电流和主磁通各为多少? (2)若U2与u2连在一起,U1-u2端加110V电压,则空载电流和主磁通又各为多少?
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(1)UU1U2=4.4fN1=220V
因为U1和u1为同名端U2与u1连接在一起为顺串若此时主磁通为
则
即主磁通保持不变而
=F0/Rm由于磁阻Rm相同故磁动势F0相同即
(2)此时绕组为反串因此
UuU1u1=UU1U2一Uu1u2
=4.4f(N1一N2)
=110V
(1)UU1U2=4.4fN1=220V因为U1和u1为同名端,U2与u1连接在一起为顺串,若此时主磁通为,则即主磁通保持不变,而=F0/Rm,由于磁阻Rm相同,故磁动势F0相同,即(2)此时,绕组为反串,因此UuU1u1=UU1U2一Uu1u2=4.4f(N1一N2)=110V
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