SRM University 2007 B.Tech Electronics and Communications Engineering BANK : CIRCUIT THEORY UNIT -I - Question Paper

56) State the relation ranging from the line and phase volumes of a balanced 3-phase wye connected system.
57) Write the expression for the wattmeter readings connected to measure the total power in a 3-phase balanced circuit.
58) When does 1 wattmeter learn zero in the two-wattmeter method of 3-phase power measurement?

PART-B
1. Write the mesh equations for the circuit shown in the figure and solve the current in the 12-ohm resistor.
2. Write and solve the equations for the mesh currents in the network in the figure

3.Frame the nodal equations of the network of the figure and hence determine the node voltages V1 & V two . Determine also the total power consumed by the network.



4. Obtain the currents in all the branches of the network shown beneath by a) Mesh method b) Nodal method
5. Determine the voltage 0V which causes the current through 6ohm resistor to be zero for the circuit shown in the figure using mesh analysis.

6. Determine the power dissipated by 5ohm resistor in the circuit shown beneath


7. Find the power delivered by 5A current source in the circuit by nodal method

8. Using mesh analysis, determine the voltage Vs which provide a voltage of 30V across the 30? resistor shown in the figure.




9. In the network shown in the figure obtain the node voltages and also the current supplied by the source.





10. Using nodal analysis, obtain the currents through the 4? resistor in the circuit shown in figure.

11. Apply the mesh method and determine currents through the resistors of the network shown in the figure.

12. A capacitor having a capacitance of 10µF is connected in series with a non-inductive resistance of 120 ? across 100V, 50Hz. compute the current, power and the phase difference ranging from current and supply voltage.

13. For the circuit provided beneath obtain the magnitude of current in every branch and the total current. What is the phase angle ranging from the applied voltage and total current?




14) Determine the total impedance, total current and phase angle for the circuit.





15)A symmetrical 3-phase, 3-wire 440V supply is connected to a star-connected load as shown in the figure. The impedances in every branch are ZR = (2+j3) ,ZY =(1-j2),
ZB =(3+j4). obtain the equivalent delta-connected load. The phase sequence is RYB


16) A Star connected load with neutral isolated, has impedances of ZA = 15 ?-300 ?,
ZB = 10 ?300 ?, ZC = 15 ?00 ?. The supply voltage is 230V, ABC system.
Taking EBC as reference, determine the line currents and the voltage across the load
impedances.

17) A 3- phase, 440V supply feeds an unbalanced, delta connected load in which
ZRY = 20 ?300 ?, Z YB = 20 ?00 ?, Z BR = 20 ?-300 ?. Phase sequence is RYB.
Determine the readings of 2 wattmeter’s which are placed in R and Y lines for
measurement of three phase power.

18) A balanced star connected load of (8+j6) ?/ phase is connected to a three phase, 230V,
50c/s supply. obtain the line current, power factor, power, reactive volt amperes and
total volt amperes.

19) 3 identical coils every having a resistance of 20 ? and a reactance of 20 ? are connected in i) star ii) delta across 440V, three phase supply. compute for every case, line current and studying in every of the wattmeters connected to measure power.

Earning:   Approval pending.