Problem solving 1-5 1. Two coils A and B known to have the same resistance are connected in series across a 110 – V, 60

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Problem Solving 1 5 1 Two Coils A And B Known To Have The Same Resistance Are Connected In Series Across A 110 V 60 1 (54.67 KiB) Viewed 29 times

Problem solving 1-5 1. Two coils A and B known to have the same resistance are connected in series across a 110 – V, 60 Hz line. The current and power delivered by the source are respectively 12.3 A and 900 W. If the voltage across the coil A is three times that across coil B, give the ratio of the inductance of coil A to the inductance of coil B. 2. A single phase load takes 75 kW at 75% p.f. lagging from a 240 V, 60 Hz supply. If the supply is made 50 Hz, with the voltage twice, what will be the kW load at this rating? Give also the complex expression of the impedance. 3. A non-inductive resistance of 15 ohms in series with a condenser takes 5 A from 220 – V,60 Hz mains. What current will this circuit take from 220 - V, 25 Hz supply? 4. An industrial coil has a resistance of 64 ohms and a reactance of 48 ohms and rated 440 V at 60 Hz. A factory will connect the coil to a 440 V, 50 Hz supply. How much percentage over current will the coil suffer? 5. A coil (RL) is connected in series with a capacitor across a 220 V, 60 Hz AC supply. The circuit is designed such that the voltage across the coil is half of that capacitor. If the circuit operates at 0.80 leading power factor, determine the magnitude of the voltage across the coil and of that capacitor. 6. Show that lave =0.6366Im. GIVE THE SOLUTION Answer Key: 1. Ratio = 2.472 2. P = 346.45 kW 3. 12 = 2.19 A 4.% overcurrent = 6 % 5. EL= 254 cis 46.15 V; Ec= 127 V 6. Derivation