Electrical Measurements Practice Test 3

1. In the Owen’s bridge shown in below figure, Z₁ = 200∠60°, Z₂ = 400∠-90°, Z₃ = 300∠0°, Z₄ = 400∠30°. Then the _______

Bridge can be balanced, if Z₃ = 400∠0°

Bridge can be balanced, if Z₄ = 600∠60°

Bridge is balanced with given impedance values

Bridge cannot be balanced with the given configuration

2. Nominal ratio of an instrument transformer is defined as the __________

reciprocal of the rated primary value

ratio of rated secondary value to primary value

reciprocal of the rated secondary value

ratio of rated primary value to secondary value

3. The primary winding of a P.T. has _________

no turns at all

a larger number of turns

intermediate number of turns

a few turns

4. The Bridge shown in the below figure is ______________

Wien’s Bridge

Anderson’s Bridge

Hay’s Bridge

Maxwell’s Bridge

5. Moving coil instruments have a current and voltage rating of __________

75 nA and 100 μV

50 mA and 50 mV

25 μA and 75 V

100 A and 25 V

6. The four arms of an AC bridge network are as follows:

Arm AB: unknown impedance
Arm BC: standard capacitor C₂ of 1000pf
Arm CD: a non-inductive resistance of R of 100 Ω in parallel to a capacitor of 0.01 μF
Arm DA: a non-inductive resistance of 1000 Ω

The supply frequency is 50 Hz and connected across terminals B and D. If the bridge is balanced with the above value, determine the value of unknown Capacitance.

100 pf

500 pf

10 pf

1000 pf

7. The secondary leakage reactance of a C.T. ____________

increases the impedance of the circuit

decreases its ratio error

has no effect on its ratio error

increases its ratio error

8. The magnitude of stray capacitances is fixed.

False

True

9. Secondary and primary windings consist of ________

copper turns

laminations

14 S.W.G copper wire and copper strip respectively

iron coils wound around

10. A Schering bridge can be used for capacitance measurements at low voltages.

False

True