典型例題變壓器

1、典型例題（變壓器）臺(tái)單相變壓器，SN=20000kVA , U 1N /U220/11kV , fN=50 赫，線圈為銅線?？蛰d試驗(yàn)（低壓側(cè)）：短路試驗(yàn)（高壓側(cè)）：為 150C）:（1）折算到高壓側(cè)的“U0=11kV、I0=45.4A、P0=47W；Uk=9.24kV、lk=157.5A、Pk=129W;試求（試驗(yàn)時(shí)溫度T”形等效電路各參數(shù)的歐姆值及標(biāo)么值（假定 rk1 =2 = ,X1 = X2 =2 2 ）;（2）短路電壓及各分量的百分值和標(biāo)么值;Xk（3）在額定負(fù)載，coS*2 二1、cos/ =0.8但2 M）和 cos2 =0.2 0）時(shí)的效率;（5）當(dāng)cos2 =0.8（2 A0）

2、時(shí)的最大效率。Uo 11咒10Zm =解：（1）低壓側(cè)勵(lì)磁阻抗i；=115T = 242-29rm低壓側(cè)勵(lì)磁電阻低壓側(cè)勵(lì)磁電抗Xm= 7zm2-rm2 =242.292 -22.82 = 241.210220廠=11.547變比 U 2N11折算到高壓側(cè)的勵(lì)磁電阻rm= K 2rm = 11.5472 X 22.8 = 30400折算到高壓側(cè)的勵(lì)磁電抗Xm = K 2Xm = 11.5472 X 241.21 = 32161.3QZk高壓側(cè)短路阻抗9 24 X103=9.24 10 = 58.670157.5UkIkrk 牛12高壓側(cè)短路電阻|k157.5高壓側(cè)短路電抗 Xk = Jzk2 -

3、k2 = J58.672 -5.22 =58.440折算到75oC時(shí)短路電阻rk7523rk=3 = 6.448。235+15235+15折算到75oC時(shí)短路阻抗Zk75c +Xk2 = J6.4482 +58.442 = 58.80T型等效電路原副邊的電阻口 =2rk75oC6=3.224T型等效電路原副邊的電抗Xk58.44Z1NU 1NU12n基準(zhǔn)阻抗I 1NSNrmrm勵(lì)磁電阻標(biāo)幺值Z1 N/3勵(lì)磁電抗標(biāo)幺值短路電阻標(biāo)幺值短路電抗標(biāo)幺值=29.22Q（220x10；）（/73）2 4 2320000 X103XmXm32161.3 =39.87Z1Nrk75oC =rk75oC6.44

4、8 =0.008乙NXk =XkZlN58.44 =0.0 7 2 42420T型等效電路原副邊電阻的標(biāo)幺值rk75oC啤=0.004T型等效電路原副邊電抗的標(biāo)幺值XiXk0.0724短路電壓的標(biāo)幺值I1NZk75oCZk75oCU1NZ1N-Zk75oC短路電壓有功分量的標(biāo)幺值Uka短路電壓無功分量的標(biāo)幺值短路電壓的百分值Ukr-X2 - 2= 0.036258.8 =0.0729I1N rk75oC k75oCU1NZ1 N=rk75oC= 0.008I 1N XkXkU 1 NZ1N=Xk=0.0724uk(%) = IJNZwc 如00(%) = zK75o100(% 7.29(%)1

5、N 厶k75oCU 1N短路電壓有功分量的百分值1 1 Nk 75。c*Uka(%)=咒 100(%) EC 000(%)=0.8(%)U 1NI1N Xk短路電壓無功分量的百分值ukr(%) =X100(%) =Xk X100(%) =7.24(%)U 1 N(3)額定負(fù)載時(shí),負(fù)載系數(shù)0 i cos2 i時(shí),sin護(hù)2 =0電壓變化率和二次端電壓分別為:iu = P(rk COSW2 +XkSin 徨)=1x0.008x1 =0.008U2 =(1-Au)U2n =(1 -0.008)x11 =10.912kV cos2 =0.8(2 0)時(shí),sin2 =0.6電壓變化率和二次端電壓分別為u

6、 = P(r； cos2 +xksin 護(hù)2) =1x(0.008x0.8+0.0724x0.6) =0.04984U2 =(1-也u)U2n =(1 -0.04984)x11 =10.452kV cos2 =0.8(2 0)時(shí)，sin2 =-0.6電壓變化率和二次端電壓分別為u = P(r； co2 +xksi門2)=1x(0.008 咒0.8-0.0724 咒 0.6) = -0.03704U2 =(1 -也 u)U2n =(1 +0.03704)X11 =11.407kV3(4) 一次側(cè)額定電流l1寶二000“U1N 220X1072 2于是滿載時(shí)的銅損耗Pkn =l1NrK75oC =

7、157.5 6.44159.9507kW效率n =(1 - P0 中 B Pkn_pc 100(%)PSn COS2 +P0 +P2Pkn2=(1 廠)x 100(%) =98.7(%)1x 20000 咒 0.8 +47 + 1 x 159.9507P（5）最大效率時(shí),負(fù)載系數(shù)為 最大效率為Po47UPKT *159.9507 0.5422P0XSNCO化 +2P0）伽（）2x47八0.542偵。心+丄川叫）%）47 +1 X 159.9507?習(xí)題教程中的重點(diǎn)習(xí)題? CH1 : 2,3,4,6,7,9,10,12? CH21,2,4,5,6,11,15,16,19,25,26,27,29,31,32,33,36,40,42,47? CH3: 2,3,5,9,10,11,15,16,24,34,35? CH4: 1,2,3,16,1