Network Theory Practice Test 5

1. A 200/1 Current Transformer (CT) is wound with 400 turns on the secondary on a toroidal core. When it carries a current of 180 A on the primary, the ratio is found to be -0.5%. If the number of secondary turns is reduced by 1, the new ratio error (in %) will be?

2. Two coils are having self-inductance of 5 mH and 10 mH and a mutual inductance of 0.5 mH in a differential connection. The equivalent inductance of the combination is ___________

3. A three-phase balanced delta connected load of (4+j8) Ω is connected across a 400V, 3 – Ø balanced supply. Determine the phase current I_R. Assume the phase sequence to be R_YB.

4. The readings of polar type potentiometer are
I = 12.4∠27.5°
V = 31.5∠38.4°
Then, Reactance of the coil will be?

5. A symmetrical three-phase, three-wire 440V supply is connected to star-connected load. The impedances in each branch are Z_R = (2+j3) Ω, Z_Y = (1-j2) Ω, Z_B = (3+j4) Ω. Find Z_BR.

6. The CT supplies current to the current coil of a wattmeter power factor meter, energy meter and, an ammeter. These are connected as?

7. In wye or star connection _____________ of the three phases are joined together within the alternator.

8. The current through an electrical conductor is 1A when the temperature of the conductor 0°C and 0.7 A when the temperature is 100°C. The current when the temperature of the conductor is 1200°C is ___________

9. The average power absorbed by an impedance Z = 30 – j 70 Ω when a voltage V = 120∠0° is applied is _____________

10. In the Delta or Mesh connection, there will be __________ number of common terminals.