Example: If VL=380V, Z,=4.5+j692, ZL=1.5+j2 Q2. Find (1)Ia4, IbB, Icc and IAB, IBC, ICA; (2)PI load Solution. L Vant L n 380 P (1 let van ∠0°=220∠0° 十 ad =44∠-53.1°A Z./3 Z,+Z/3 L Z./3 AB ∠30°=25.4∠-23.1°A 3×2×R Z.13 =3×25.42×4.5=8710W
Example: If VL=380V,Zp =4.5+j6Ω, ZL =1.5+j2 Ω. Find a b c n • V bn • + + + − − − A B C Z p Z p Z p V an • V cn • ZL ZL ZL (1) I aA,I bB ,I cC and I AB ,I BC ,I CA; • • • • • • ( ) P . 2 load Solution: ( ) let V an V 0 220 0 3 380 1 = = • A Z Z V I L p a n a A 44 53.1 / 3 = − + = • • − + • V an − + • V bn − + • V cn ZL ZL ZL / 3 Z p n N a A / 3 Z p / 3 Z p − + • V an N a A ZL / 3 Z p A I I aA AB 30 25.4 23.1 3 = = − • • . . W ( ) Pload I p Rp 3 25 4 4 5 8710 2 3 2 2 = = =
The three-phase circuits analysis 1. a balanced three-phase circuit (1)The balanced three-phase system=>Y-Y (2) Draw a phase circuit(a phase), then find voltages and currents of a phase(a phase); (3)Direct write other two phase(B, c) voltages and currents from the balanced relationship; (4)Find voltages and currents of the original circuit from the y-4 transformation
The three-phase circuits analysis 1. A balanced three-phase circuit (1) The balanced three-phase system => Y-Y; (2) Draw a phase circuit (A phase), then find voltages and currents of a phase(A phase); (3) Direct write other two phase(B,C) voltages and currents from the balanced relationship; (4) Find voltages and currents of the original circuit from the Y- transformation