# High Voltage Engineering Questions and Answers – Impulse Voltage Measurement

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

1. For measuring only the peak measurements _________ are used.
a) sphere gaps
b) series capacitance voltmeter
c) capacitance Potential Dividers
d) capacitance voltage transformers

Explanation: Sphere gap is used for the measurement of peak value of ac, dc and impulse voltage. It is also used for the checking of voltmeters. It finds a major use in high voltage testing devices. It is mainly used for calibration purposes too.

2. Which among the following is the oldest device for ac measurements?
a) Sphere gaps
b) Series capacitance voltmeter
c) Capacitance Potential Dividers
d) Potential transformers

Explanation: Magnetic potential transformers are the oldest devices for ac measurements. They can be designed for any voltage and they are simple in construction. Cascading of transformers is done for very high voltage.

3. _________ is the impulse voltage developed without causing puncture or flashover.
a) Normal impulse voltage
b) Chopped impulse voltage
c) Full impulse voltage
d) Clean impulse voltage

Explanation: The full impulse voltage is the impulse voltage developed without causing puncture or flashover. It is characterized by its two time intervals and the peak value. The time intervals are wave front time and wave tail time.

4. An impulse voltage is a unidirectional voltage.
a) True
b) False

Explanation: An impulse voltage is a unidirectional voltage. It does not have much oscillations. It rises to a peak value and decays to more or less a zero value.

5. What is the type of voltage dividers used for the impulse voltage measurement?
a) damped capacitor type
b) resistor type
c) inductive type
d) damped capacitor type or resistor type

Explanation: The type of voltage dividers used for the measurement is damped capacitor type or resistor type. Oscilloscopes are used for recording the voltage and sometimes sphere gaps are used for calibration process.

6. Peak voltmeters and sphere gaps can be used for impulse voltage measurements.
a) True
b) False

Explanation: Peak voltmeters and sphere gaps can be used for impulse voltage measurements. Sphere gap is used for the measurement of peak value of ac, dc and impulse voltage. It is also used for the checking of voltmeters. It finds a major use in high voltage testing devices. Peak voltmeters are used to measure the peak value of impulse voltages.

7. __________ form a voltage generating system.
a) Voltage generator
b) Test object
d) Voltage generator, test object and lead

Explanation: Voltage generator, test object and lead form a voltage generating system. The voltage divider used for impulse voltage measurement testing requires a special design. The lead L consists of a lead wire and resistance to damp oscillations.

8. What is the clearance between the top electrode and ground (in voltage dividers) for lightning impulse voltage?
a) 2-2.5m/MV
b) 3m/MV
c) 5m/MV
d) 10m/MV

Explanation: The clearance between the top electrode and ground (in voltage dividers) for lightning impulse voltage is 2-2.5m/MV. The height of the divider becomes large for voltage of megavolt range. The height is also dependent on the flashover voltage.

9. What is the clearance between the top electrode and ground (in voltage dividers) for switching impulse voltage?
a) 1m/MV
b) 2m/MV
c) 3m/MV
d) above 4m/MV

Explanation: The clearance between the top electrode and ground (in voltage dividers) for switching impulse voltage is more than 4m/MV. The height of the divider becomes large for voltage of megavolt range. The height is also dependent on the flashover voltage.

10. The length of the voltage divider depends on __________
a) maximum voltage to be measured
b) resistance
d) maximum voltage to be measured, resistance and surface flashover gradient

Explanation: The length of the voltage divider depends on maximum voltage to be measured, resistance and surface flashover gradient. The resistance of the potential divider must be matched with the equivalent resistance of a given generator to obtain a given wave shape.

Sanfoundry Global Education & Learning Series – High Voltage Engineering.

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