Category: Generation of High Voltage and Currents

Cascade Transformer Connection

Cascade Transformer Connection: Figure 6.10 shows the Cascade Transformer Connection units in which the first transformer is at the ground potential along with its tank. The second transformer is kept on insulators and maintained at a potential of V2, the output voltage of the first unit above the ground. The high voltage winding of the […]

Tripping of Impulse Generators

Tripping of Impulse Generator: In large impulse generator, the spark gaps are generally sphere gaps or gaps formed by hemispherical electrodes. The gaps are arranged such that sparking of one gap results in automatic sparking of other gaps as overvoltage is impressed on the other. In order to have consistency in sparking, irradiation from an […]

Generation of Impulse Currents Waves

Generation of Impulse Currents Waves: Lightning discharges involve both high voltage impulses and high current impulses on transmission lines. Protective gear like surge diverters have to discharge the lightning currents without damage. Therefore, generation of impulse currents waveforms of high magnitude ( ≈ 100 kA peak) find application in test work as well as in […]

Generation of Switching Surges

Generation of Switching Surges: Nowadays in extra high voltage transmission lines and power systems, switching surges is an important factor that affects the design of insulation. All transmission lines rated for 220 kV and above incorporate switching surge spark overvoltage for their insulation levels. A switching surges is a short duration transient voltage produced in […]

Multistage Impulse Generator Circuit

Multistage Impulse Generator Circuit: In the early discussion, the generator capacitance C1 is to be first charged and then discharged into the wave shaping circuits. A single capacitor C1 may be used for voltages up to 200 kV. Beyond this voltage, a single capacitor and its charging unit may be too costly, and the size […]

Series Inductance in Impulse Generator Circuit

Series Inductance in Impulse Generator Circuit: Often Series Inductance in Impulse Generator Circuit are required to test equipment with large inductance, such as power transformers and reactors. Usually, generating the impulse voltage wave of proper time-to-front and obtaining a good voltage efficiency are easy, but obtaining the required time-to-tail as per the standards will be […]

Circuits for Producing Impulse Waves

Circuits for Producing Impulse Waves: A double exponential waveform of the type mentioned in Eq. (6.15) may be produced in the laboratory with a combination of a series R-L-C circuit under over damped conditions or by the combination of two R-C circuits. Different equivalent circuits that produce impulse waves are given in Figs 6.15a to […]

Standard Impulse Wave Shapes

Standard Impulse Wave Shapes: Transient overvoltages due to lighting and switching surges cause steep build-up of voltage on transmission lines and other electrical apparatus. Experimental investigations showed that these waves have a rise time of 0.5 to 10 μs and decay time to 50% of the peak value of the order of 30 to 200 […]

Generation of High Frequency AC High Voltage

Generation of High Frequency AC High Voltage: High Frequency AC High Voltage are required for rectifier d.c power supplies. Also, for testing electrical apparatus for switching surges, High Frequency AC High Voltage damped oscillations are needed which need high voltage high frequency transformers. The advantages of these high frequency transformers are: the absence of iron […]

Resonant Transformers

Resonant Transformers: The equivalent circuit of a high voltage testing Resonant Transformers consists of the leakage reactance of the windings, the winding resistances, the magnetizing reactance, and the shunt capacitance across the output terminal due to the bushing of the high voltage terminal and also that of the test object. This is shown in Fig. […]