ECE 22 Electrical Power - AC Parallel Circuits - Part 2 Q&A | ECE 22 De La Salle University - Dasmariñas

ECE 22 Electrical Power - AC Parallel Circuits - Part 2 Q&A | ECE 22 De La Salle University - Dasmariñas A resistance of 20 W and a coil of inductance 31.8 mH and negligible resistance are connected in parallel across 230 V, 50 Hz supply. Find (i) The line current (ii) power factor and (iii) The power consumed by the circuit. 2. Two impedances Z1 = (150 + j157) ohm and Z2 = (100 + j 110) ohm are connected in parallel across a 220-V, 50-Hz supply. Find the total current and its power factor. 3. Two impedances (14 + j5) Ω and (18 + j10) Ω are connected in parallel across a 200-V, 50-Hz supply. Determine (a) the admittance of each branch and of the entire circuit; (b) the total current, power, and power factor and (c) the capacitance which when connected in parallel with the original circuit will make the resultant power factor unity.4. A parallel circuit consists of two branches A and B. Branch A has a resistance of 10 Ω and an inductance of 0.1 H in series. Branch B has a resistance of 20 Ω and a capacitance of 100 μF in series. The circuit is connected to a single-phase supply of 250 V, 50 Hz. Calculate the magnitude and the phase angle of the current taken from the supply. Verify your answer by measurement from a phasor diagram drawn to scale. 5. Two circuits, the impedances of which are given by Z1 = (10 + j15) Ω and Z2 = (6 −j8) Ω are connected in parallel. If the total current supplied is 15 A, what is the power taken by each branch? 6. A voltage of 240 V is applied to a pure resistor, a pure capacitor, and an inductor in parallel. The resultant current is 2.3 A, while the component currents are 1.5, 2.0 and 1.1 A respectively. Find the resultant power factor and the power factor of the inductor. 7. Two parallel circuits comprise respectively (i) a coil of resistance 20 Ω and inductance 0.07 H and (ii) a capacitance of 60 μF in series with a resistance of 50 Ω. Calculate the current in the mains and the power factor of the arrangement when connected across a 200-V, 50-Hz supply.