This Portion of Electrical andElectronic Measurements and Measuring instruments contains High Voltage Measurements and Testing MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.
This Section covers below lists of topics.
- Types of Tests
- Testing Apparatus
- Control Gear and Protective Devices
- Equipment for Voltage Measurement
- Low Frequency H.V Tests
- High Voltage D.C Testing
- High Voltage D.C Testing for Cables
- Localization of Faults in High Voltage Cables
- High Frequency High Voltage Tests
- Surge (Impulse) Testing
- Testing of insulating materials
- High Voltage Testing of cables
- High Voltage Tests on Porcelain insulators
- Testing of Electric Strength of insulating Oils
PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE
1. A.C transmission lines and cables are tested by using d.c
- They may be used for d.c if required
- They draw high values of charging current and hence would require a large sized h.v transformer if tested with a.c
- H.v testing transformers cannot be used for long times that required for testing
- All the above.
B. They draw high values of charging current and hence would require a large sized h.v transformer if tested with a.c
2. High frequency high voltage tests are carried out on porcelain insulators because
- They can withstand an a.c voltage at low frequency but fail to withstand that voltage applied at high frequency
- The insulators, though used on power frequency circuits, may be subjected to high frequency voltages on account of disturbances caused by switching which produce high dielectric loss and heating that may cause failure of insulator at a lower voltage
- The insulators may be used for communication purposes wherein the frequency may be of the order of MHz.
- All the above.
D. All the above.
3. If the sizes of power transformers and high voltage testing transformers of equal kVA rating are compared :
- The size of h.v testing transformer is greater than that of a power transformer
- The size of h.v testing transformer is smaller than that of a power transformer
- The size of h.v testing transformer is same as that of the power transformer
- None of the above
A. The size of h.v testing transformer is greater than that of a power transformer
4. Cascade connection of transformer is normally used when a single transformer cannot be used because the minimum testing voltage:
- Is about 100 kV
- Is about 500 kV
- Is about 1000 kV
- All the above.
B. Is about 500 kV
5. The voltage control circuit cannot use resistance potential dividers because:
- They involve a large power loss
- They cause distortion of waveform
- They do not give smooth variation of voltage
- They have non-linear characteristics
A. They involve a large power loss
6. Sphere gaps are used for measurement of :
- Instantaneous values of voltage
- R.m.s values of voltage
- Peak values of voltage
- Average values of voltage.
C. Peak values of voltage
7. A Cockroft Walton circuit for generation of high voltage d.c has n stages . if the voltage of secondary windings of the high voltage transformer is
- Vm the output voltage of the circuit is :nVm
- Vm the output voltage of the circuit is :2(n -1)Vm
- 2(n +1)Vm
- 2nVm
D. 2nVm
8. The impulse voltage wave shape is defined as t1 / t2 where :
- t1 = time taken by the impulse voltage to rise to its peak and t2 = time taken to fall to zero
- t1 = time taken by the impulse voltage to rise to its peak and t2 = time taken to fall to 50% of its peak
- t1 = time taken by the impulse voltage to rise to 50% of its peak and t2 = time taken to fall to zero
- none of the above
B. t1 = time taken by the impulse voltage to rise to its peak and t2 = time taken to fall to 50% of its peak
9. In a Marx’s circuit,
- The capacitors are charged in series and discharged in series
- The capacitors are charged in parallel and discharges in parallel
- Are charged in series and discharged in parallel
- Charged in parallel and discharged in series
D. Charged in parallel and discharged in series
10. The electric strength of new insulating oil should have a minimum strength (r.m.s) of
- 30 kV / mm
- 3 Kv/mm
- 50 kv/mm
- 5 kv/mm
B. 3 Kv/mm
