Generating Voltmeter (GVM) Principle of Operation Generating Voltmeter (GVM) : The generating voltmeter comprises essentially of an insulated stator mounted facing the high voltage terminal. It is periodically shielded from this high voltage terminal by the rotation of a grounded sectored disk at a constant speed. The stator to terminal capacitance is thus caused to vary periodically … Read more

Electrostatic Voltmeter Q. Explain with neat diagrams the principle of operation of an electrostatic voltmeter Discuss its advantages and limitations for high voltage measurements. Principle : In electrostatic fields the attractive force between the electrodes of a parallel plate condenser is given by, F = I – 𝛿ws /ds I = I 𝛿 / 𝛿S  (1 / … Read more

High DC Voltage Measurement The general objectives of D.C voltage measurements are : To measure the arithmetic mean value of the voltage , typically with an error of not more than 3%. To measure the ripple amplitude, typically with an error of not more than 10% of the actual ripple amplitude or not more than … Read more

Sphere Gap Meter Q. Explain how a sphere gap can be used to measure the peak value of voltages. What are the parameters and factors that influence such voltage measurement ? It is one of the standard method for measurement of peak value of DC, AC and impulse voltage and used for checking the voltage … Read more

Peak (Amplitude) Reading Voltmeter In some cases such as lightning discharges, electric arcs, post arcs in circuit breakers, study of plasma physics, it becomes necessary to determine the peak (amplitude) and wave forms of rapidly varying high currents. The current amplitude may range from few amperes to few hundred kilo amperes. Rate of rise of … Read more

Testing Transformers High Voltage power frequency test transformers are required to produce single phase very high voltages. Their continuous current ratings are very low, usually ≈ 1A. Even 1A is a very high current rating. This is because a HIV test transformer has to supply only the capacitive charging current to the capacitance formed by the dielectric … Read more

Electrostatic Generator  Q. How does an electrostatic generator work?  Q. What is a large electrostatic generator called?  Q. Electrostatic generator working principle The drawbacks of Van de Graaff generators are that these are essentially high voltage but low power devices, and their power rating seldom exceeds few tens of kilowatts. Therefore, electrostatic generators which effectively … Read more

Van de Graaff Generator Q. With a neat sketch, explain the working of a Van-De-graff generator. What are the factors that limit the maximum output voltage obtained ? A Van de Graaff generator is a device that creates high electric potential. The Van de Graff generator was invented by Robert J. Van de Graaff, and … Read more

Electrostatic Machines Two kinds of electric energy : Static electricity and Current electricity. When an electrostatic force acts between charged particles , assign an electric potential energy, U. The difference in U of the system in two different states, initial i and final f, is ∆U = Uf  – Ui Reference point : Choose U = … Read more

Cockroft Walton Voltage Multiplier Circuit Q. Why is Cockcroft-Walton circuit preferred for voltage multiplier circuits? Explain its working with a schematic diagram. Q. Derive an expression for ripple voltage of a Multistage Cock Croft-Walton circuit. It is possible to generate very high DC voltages from single supply transformers by extending the voltage doubler circuit. This … Read more