##### BOARD DIPLOMA EXAMINATIONS, (C-14)

DEEE-THIRD SEMISTER EXAMINATIONS

MODEL PAPER-I

ELECTRICAL CIRCUITS

SUB CODE:EE-303

##### Time: 3 Hours Total marks: 80

###### PART-A 10 X 3=30

**Instructions: 1) Answer all questions.**** 2) Each answer carries three marks.**** 3) Answer should be brief and straight to the point and shall not exceed **** five simple sentences.**

- Define (a) Active circuit (b) Passive circuit (c) linear circuit?
- State Kirchhoff’s laws?
- Define (a) Frequency (b) Form factor (c) Peak factor?
- Convert the rectangular form (10+j15) into polar form?
- Write an expression for RMS value and average value of full wave rectified sine wave?
- Define Q-Factor series resonant circuit?
- The current flowing through a pure capacitor is 23amps.Find the capacitance, when the voltage applied across the capacitor v=200sin314t.
- Define Resonance and write the equation for resonant frequency for parallel circuit?
- State the relation between the line voltage and phase voltage, line current and phase current in star connected network?
- (a) Define the term “Poly phase ”

(b) What is meant by phase sequence?

**PART-B 5 X 10=50**

**Instructions: 1) Answer any five questions.**

**2) Each answer carries ten marks.**

11.A wheat stone bridge ABCD is arranged as follows. AB=10 ohm, BC=10 ohm, CD=4 ohm, DA=50 ohm. A galvanometer of 20 ohm resistance is connected across BD. Calculate the current through the galvanometer when p.d of 10 volts is maintained across A&C.

12. Derive the formulas for star to delta transformation.

13. State and explain Maximum power transfer theorem and mention its applications.

14. (a) Define RMS value and Average value?

(b) A sinusoidal wave is represented by i=42.42sin628t. Determine its (a) RMS value (b) form factor (c) peak factor.

15. A coil of resistance 100 ohms and inductance of 0.318 H is connected in series with a capacitor across a 230 V, 50 Hz, AC Supply. If the current drawn is 1.15/͟60° amps. Calculate the capacitance of the capacitor, voltage across inductance and power consumed in the circuit.

16. A coil of resistance 2 ohms and inductance of 0.01 H is connected in series with a capacitor across 200 V supply. What must be the capacitor in order that maximum current occurs at a frequency of 50 Hz. Also find (a) maximum current (b) voltage across the coil (c) voltage across the capacitor.

17. A circuit of (10+j15) ohms is connected in parallel with another circuit of (6-j8) ohms this is connected across 220 volts, 50 Hz, AC supply. Find (a) total current (b) total power drawn by the circuit. Also draw the vector diagram.

18. A 3 phase 400 volts motor has a power factor of 0.4 lagging. Two watt meters are connected in the circuit to measure the input. They show that the input to be 30 kw.find the reading of each instrument.