Transmission and distribution of electrical energy involves the application of highvoltage
apparatus like power transformers, switchgear, overvoltage arrestors,
insulators, power cables, transformers, etc., which are exposed to high transient
voltages and currents due to internal and external overvoltages. Before commissioning,
they are therefore tested for reliability with standard impulse voltages or
impulse currents. Depending on the apparatus and the type of their proposed
application, one differentiates between various types of waveforms of test voltages
and test currents. These waveforms are defined by several parameters with tolerances
during generation and uncertainties during measurement. For data evaluation
of these waveforms, measured, as a rule, with digital recorders, partially
standardised evaluation procedures are applied. Thereby, experimental data
obtained from extensive investigations with respect to the evaluation of peak
oscillations, which are superimposed on a lightning impulse voltage, are taken into
account as a function of the oscillation frequency. In the second part of this
chapter, various circuits for the generation of high impulse voltages and impulse
currents will be discussed in principle