# High Voltage Engineering Questions and Answers – Generation of Impulse and Rectangular Current

This set of High Voltage Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Generation of Impulse and Rectangular Current”.

1. Wave shapes used in testing surge diverters are __________
a) 120/2500 μs
b) 4/10 μs
c) 8/20 μs
d) 4/10 μs and 8/20 μs

Explanation: Wave shapes used in testing surge diverters are 4/10 μs and 8/20 μs. These are the standard impulse waves used for testing. Rectangular waves of long duration are also often used for testing.

2. The electric arc studies involves the use of impulse current waveforms of magnitude __________
a) 10kA
b) 100kA
c) 1000kA
d) 5000kA

Explanation: The electric arc studies involves the use of impulse current waveforms of magnitude 100kA. Usually high current ratings are preferred. They are also used in research of non-linear resistors.

3. The basic research on non-linear resistors involves the use of impulse current waveforms of magnitude __________
a) 10kA
b) 100kA
c) 1000kA
d) 5000kA

Explanation: The basic research on non-linear resistors involves the use of impulse current waveforms of magnitude 100kA. Usually high current ratings are preferred.

4. The rise and fall time of rectangular waves should be less than __________ of their total duration.
a) ±1%
b) ±5%
c) ±10%
d) ±20%

Explanation: The rise and fall time of rectangular waves should be less than ±10% of their total duration. The duration of the rectangular wave is 0.5-5ms. Generally, the wave shape should be rectangular in shape.

5. What is the duration of the rectangular waves?
a) 2-5ms
b) 0.5-5ms
c) 10ms
d) 10-20ms

Explanation: The duration of the rectangular waves is 0.5-5ms. Generally, the wave shape should be rectangular in shape. The rise and fall time of these waves should be less than ±10% of their total duration.

6. High voltage impulses and high current impulses are involved in the lightning discharges on transmission lines.
a) True
b) False

Explanation: High voltage impulses and high current impulses are involved in the lightning discharges on transmission lines. Surge diverters or surge arrestors are used to discharge the lightning current without damage.

7. The circuit for producing impulse current wave is usually damped.
a) True
b) False

Explanation: The circuit for producing impulse current wave is usually undamped. A bank of capacitors connected in parallel are charged to a voltage and discharged in series through an R-L circuit.

8. A bank of capacitors connected in __________ are charged to a voltage and discharged in _____ through an R-L circuit for producing impulse current of high value.
a) series, series
b) series, parallel
c) parallel, parallel
d) parallel, series

Explanation: A bank of capacitors connected in parallel are charged to a voltage and discharged in series through a R-L circuit for producing impulse current of high value. The circuit for producing impulse current wave is usually undamped.

9. Identify the following figure.

a) Pulse waveform using pulse forming network
b) Pulse waveform using a coaxial cable
c) Impulse waveform
d) Square waveform

Explanation: The figure represents Pulse waveform using a pulse forming network. The duration of the rectangular wave is 0.5-5ms. Generally, the wave shape should be rectangular in shape. The rise and fall time of these waves should be less than ±10% of their total duration.

10. Identify the following figure.

a) Pulse waveform using pulse forming network
b) Pulse waveform using a coaxial cable
c) Impulse waveform
d) Square waveform

Explanation: The figure represents a pulse waveform using a coaxial cable. The duration of the rectangular wave is 0.5-5ms. Generally, the wave shape should be rectangular in shape. The rise and fall time of these waves should be less than ±10% of their total duration.

11. What is the duration of pulse waveform formed using a pulse forming network?
a) 1 μs
b) 1.5μs
c) 3 μs
d) 3.5μs

Explanation: The duration of pulse waveform formed using a pulse forming network is 3.5μs. The following figure represents a pulse waveform using a pulse forming network. The duration of the rectangular wave is 0.5-5ms. Generally, the wave shape should be rectangular in shape. The rise and fall time of these waves should be less than ±10% of their total duration.

12. The duration of pulse time in seconds of a rectangular wave is given by __________
a) 2n$$\sqrt{LC}$$
b) n$$\sqrt{LC}$$
c) 2(n+1)$$\sqrt{LC}$$
d) 2(n-1)$$\sqrt{LC}$$

Explanation: The duration of pulse time in seconds of a rectangular wave is given by 2(n-1)$$\sqrt{LC}$$. C is the capacitance per stage, n is the number of stages and L is the inductance per section. Artificial transmission lines are often used to produce the waveform.

13. What is the range of capacitors in an impulse current generator circuit?
a) 20-30nF
b) 10-100nF
c) 0.5-5μF
d) 1-10nF

Explanation: The range of load capacitors in an impulse generator circuit is 1-10nF. They are capable of giving high short circuit currents.

14. What is the surge impedance to produce a rectangular pulse?
a) Z=$$\sqrt{L/C}$$
b) Z=2$$\sqrt{L/C}$$
c) Z=2$$\sqrt{C/L}$$
d) Z=$$\sqrt{C/L}$$

Explanation: To produce a rectangular pulse, the surge impedance of the coaxial cable used is Z=$$\sqrt{L/C}$$. L is the inductance per unit length and C is the capacitance per unit length. Initially, the length of cable is charged to a dc voltage which is generally specified.

15. What is the duration of pulse waveform formed using a coaxial cable?
a) 1 μs
b) 1.6μs
c) 3 μs
d) 3.6μs

Explanation: The duration of pulse waveform formed using a coaxial cable is 3.6μs. The following figure represents a pulse waveform using a coaxial cable. The duration of the rectangular wave is 0.5-5ms. Generally, the wave shape should be rectangular in shape. The rise and fall time of these waves should be less than ±10% of their total duration.

Sanfoundry Global Education & Learning Series – High Voltage Engineering.

To practice all areas of High Voltage Engineering, here is complete set of Multiple Choice Questions and Answers.

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