电工电子技术习题答案第四章ppt课件VIP

.,1,41已知i=5.6sin(314t37)A,u=311sin314tV。,解：,Um=311V,Im=5.6A,u=i=314rad/sfu=fi=/2=50HzTu=Ti=1/f=0.02su=0i=37,(2),=ui=37u超前i37,(3),(4),.,2,42已知u1=100sin(t+/6)V,u2=60sin(t+)V,试求u=u1+u2在U为最大和最小时，=？Um=？,解：,当=/6时，Um最大，Um=100+60=160V,当=-5/6时，Um最小，Um=10060=40V,30,30,.,3,43已知电路中某元件u和i，试问是什么元件、元件的参数、储能的最大值、平均功率。,(1)u=100sin(314t)Vi=10cos(314t)A,=100sin(314t+180)V,=10sin(314t90)A,u超前i90，元件为电感XL1001010Q100102500VarP0,(2)u=282sin(314t+60)Vi=56.6cos(314t30)A,=56.6sin(314t60)A,u、i同相，元件为电阻R28256.65Q0P28256.627980.6W,(3)u=70.7cos(314t30)Vi=5sin(314t30)A,=70.7sin(314t+60)V,=5sin(314t150)A,U滞后i90，元件为电容XC70.7514.14Q70.752176.75VarP0,.,4,解：,XL2fL8Z6+j81053.13IU/z22A,44将电感L25.5mH，R=6的线圈接到f=50Hz，U=220V的电源上，求XL、Z、，画相量图。,53.13,设,.,5,C,u1,u2,R,45R100，u1的f500Hz，要求输出信号u2比输入信号u1超前60，求C？,XC=|Rtan|=173.2C12fXC=1.84F,设为参考正弦量,则的初相角为0,则的初相角为60,.,6,46已知i=5.6sin（314t17)A，u=314sin（314t+20)V，试求串联等效电路。,i,+,u,N,解：,串联等效电路R=zcos37=44.7X=zsin37=33.7,R=70.2X=93.2,并联等效电路,.,7,47已知İS20A,Z1=j5，Z2=(2+j)，Z3=(3+j4)，求各个电流及各个电压。,按分流公式：,.,8,R1,XL,XC,İ,İ1,İ2,45,作相量图：,İ1=1090A,İ=İ1+İ2100A,Uab=USU150V,a,b,48图中,=314rad/s,US=100V，R1=5，I1=10A，I210A，RL=XL，求I、RL、L、C。,RL,İ2=1045A,RL=XL,zL=Uab/I2=3.5,RL=XL=2.5L=2.5/314=7.96mHC=1/5314=0.637mF,设为参考正弦量,.,9,49电路如图，标出各表读数。,L,C,3A,5A,i1、i2反相I0I1I2532A,R,C,10V,10V,.,10,L,C,10A,R,100V,5,5,10,İ1=1090,İR=1045,İ0=İ1+İR=100,.,11,R,L,C,410电路如图，R=XL5，XC10，V1读数为10V，求各表读数。,I=V1/R=2AV2IXL10VV3IXC20VV4V3V210V,.,12,411已知U=220V,U1=120V,U2=130V,f=50Hz,R1=50,求RL和L。,L,U,U2,R1,U1,RL,解：,I=U1/R1=2.4Az=U/I=220/2.4=91.67,I,由已知可列方程组：,z2=(R1+RL)2+XL2,解得:RL=29.69XL=45.3L=XL/2f=0.144H,.,13,1,Z,Z,2,Z,412已知120,Z=（+j），Z1=(3+j4)，Z2=(44j)，求各个电流及各个电压。,.,14,R1,L,u,i,C,i2,i1,R2,解：,Z1=jXL+R1=j4+3=553.13Z2=R2jXC+=8j6=1036.86,XC=6,XL=4,.,15,İ=İ1+İ2=44j22=49.226.56,cos=cos26.56=0.9,P=UIcos=9741.6WQ=UIsin=4840.6VarS=UI=10824VA,.,16,414已知U=220V，I=4A，P160W,f=50Hz，试求R、L。,0.18,=79.5,UR=Ucos=40VRPI210,XL=Rtan=54LXL2f=0.172H,.,17,1,Z,R,2,Z,.,18,416图示正弦交流电路中,U=220V，U与I同相，R=XC，求UL、UC。,R,XL,XC,İ,45,作相量图：,UL=U=220V,.,19,R1,L,u,i,R,R2,i2,i1,设İ=100,按分流公式：,5,8,2,4,=453.13A,=8.2522.83A,=81.429V,P=UIcos9=81.42100.988=804.2W,.,20,R1,L,u,C,i2,i1,R2,418电路如图，R1=5,R2=3,XL2，XC3，V读数为45V，求A表读数。,A,V,I2=UR2=15A,设İ=150,İ=İ1+İ2=22.4628.9I22.46A,.,21,R1,L,u,C,i2,i1,R2,419R1=R2=30,XLXC30，,ab,i,İ=İ1+İ2=20,.,22,1,Z,2,Z,i2,i1,i,u,420u=220sin314tV，总的S=5KVA，Z1的cos1=1，Z2的cos2=0.5，电路总的cos=0.8，试求P1、P2。,PScos=4KW=P1+P2QSsin=3KVar=Q2,P2UI2cos2=1731.4WP1=PP2=2268.6W,.,23,421iR=2sin2000tA,R=200，L=0.1H,C=2.5F,求i1、iC、uR、UL、US、cos、P、Q、S,画相量图。,R,XL,XC,İ1,XC=200,XL=200,İR=10İC=190,cos=cos45=0.707,P=UIcos=200WQ=UIsin=200VarS=UI=282.84VA,.,24,R1,X1,u,XC,i,i1,R,422图示正弦交流电路中,U=120V,İ1超前于İ相位90,R+jX=11+j8,R1+jX1=30+j50,求XC。,X,1=(9036)=54,XC=