Question

1. Two electrical loads are connected in parallel to a 380 V, 50 Hz, three phase supply. The first load consists of three identical impedance each 7 Ω resistance and 5Ω inductive resistance, connected in star. The second load consists of three identical impedances, each 12 Ω resistance and 8 Ω capacitive reactance connected in delta.

1. Sketch the arrangement described above
2. Calculate Z_ph1 and Z_ph2[Z_ph1= 8.6Ω 35.54°; Z_ph2= 14.42 Ω -33.69°]
3. Determine

1. I_ph1 and I_ph2[I_ph1= 25.51A -35.54°; I_ph2= 26.35A +33.69°]
2. I_L1 and I_L2[I_L1= 25.51A -35.54°; I_L2= 45.64A +33.69°]
3. Total current taken from the supply [I_T= 59.675A 10.137°]
4. Overall power factor of the two loads [0.98 leading]
5. Total electrical power, wattful power and reactive power taken from the supply [S= 39.3 kVA, P=38.66 kW, Q= 6.913 kVAR leading]

4. Sketch the

1. Phasor diagram in amps showing both loads and total current taken
2. Load diagram in S, P and Q, showing both loads and the total values

Answer 1

Ja 70 Phi amta 3804 sotz -j8 12 Ephi = 7+15) Zehr = 806 135:540 » 7 Izanil- 572+52 = 8.6 12ph.- ton($) -35.54. Eph2 = 12-j8 Zphy = 14.42 -3369 l Iphi a = 380 Le 28 6 (+35-39) 25.511-35.54 . E (the 2 the 380/0 BxZeb, 58 2ph2 Iphy = . 380 L 16.42 (-33.69 =26.35 (33.69, A for for star Load 0 delta Lood h = Dpb= 25.51 235.54 FL= (3x Iph = 45.64 [33-69 A It - ILI+ Izz = 25.514-35.54 + 45.64|33.69 If = 59.675 110.132° A e I 1. Us power factor= cosø= cos((0.137)= 0.98 leading (As It leads) Sa Bu_53x380x (52.675 L-60-131) - 38.6676-913 -- P+ja

phasor diagram FL= 26.35/33.610 9.675 10.137 A X 33.69 T0 1370 10.1370 vs 380 -35-54 _ 7=25.50 IL W Load diagram P= 38.66kw <) 10.139° S: 39.3KVA @=6.913 KUVA