Deepakkumar Yadav
Resonant Transformers Q. Describe the principle of operation of a resonant transformer ? How to advantageous over the cascade connected transformers ? Resonant transformer work on the principle that the load capacitance is variable and for certain loading when the capacitance is equal to inductance of the circuit resonance may occur. Under this condition then, … Read more
Cascade Transformers Q. What is Cascaded Transformer? Explain why cascading is necessary? With neat diagram, explain a three stage Cascaded transformer system. Necessity of Cascade Transformers : For higher voltage greater than 700 kV` single unit constructions becomes difficult and costly due to insulation problems. Figure A Also, transportation and erection of large transformers become difficult. The … Read more
Types of Devices to Measure High Currents Use of co-axial park’s shunt Squirrel cage shunt. Use of Rogowski coils Use of magnetic links Faraday’s ammeters C.R.O.
Use of Current Transformer (CT) for High Current Measurement Difference in Use of CT and Shunt Sr. No. CT Shunt 1. Power loss in measuring is very small or Nil. Power loss is more when shunt is used for H. V. Current measured. 2. Electrical isolation from High voltage circuits in power system. Electrical isolation … Read more
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