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As noted above, the world in its evolution has reached the stage that calls for the development of new global approaches to a solution of the most complicated current problems.

At present, the electric power is the product that is compelled to be consumed during manufacture.

The first chapter in this textbook should provide insights into the influence of power engineering on the present day civilization. It is through an understanding of the past developments and achievements we can understand our present and forge ahead to future advances.

Over the past century, the electric power industry continues to contribute to the welfare, progress, and technological advances of the human race.

The primary reason for big popularity of the conversion of heat to electric power (about 70% of the total electricity production) has been the relatively low cost of fossil fuel sources (oil, coal, and natural gas) and the reasonably high system efficiencies that can be achieved owing to the high temperature differentials created by fossil-fuel combustion. Numerous sources indicate that the use of fossil fuels for power production must reduce to the level of sustainability, which means that alternative sustainable and environmentally responsible methods must be investigated and commercialized.

The initial stages in the development of power transmission systems were discussed in Chap. 2. Here we briefly describe the steps of further development of these systems in the XXth century and in the first decade of the XXIst century and organizational problems appearing in this process.

Most research associated with alternative methods of power generation have concentrated on relatively high efficiency systems, as this makes commercial realization more readily achievable.

This chapter describes a brief perspective of development of electric power systems. This is not a detailed historical review, but rather it uses historical landmarks as a background to highlight the features and structure of the modern power systems discussed in the next chapters.

From a large variety of energy resources occurring in nature and mentioned in Chap. 1, we recognize the main resources used in large amounts for human needs.

Electrical breakdown of any dielectric medium, as with any material process, develops with limited velocity. Its development and completion require a characteristic time. If the voltage duration on a discharge gap is less than this time, the phenomenon of breakdown (discharge) delay is observed. Therefore, its implementation calls for the creation of high voltage difference between the electrodes. The dependence of the breakdown voltage of the discharge gap on the voltage duration (voltage-time curve) for different dielectric media is different. Furthermore, it depends on the configuration of the field, the shape of the applied voltage, the length of discharge gap, etc.

Operational conditions for HES insulation differ from those for insulating power and electrotechnical systems.

One of the main characteristics of insulation of high-voltage systems is the permissible working field strength. The permissible field strength is chosen based on static, voltage—time, and statistical characteristics. In Part 2, the experimental results were presented that mainly concerned the first two characteristics. In Chapter 11, methods for calculating these characteristics for various dielectric media are summarized, the statistical nature of breakdowns (the distribution function of U br) is analyzed, the necessity of its consideration in calculation and coordination of HES insulation is demonstrated, and methods for calculating the operating lifetime and reliability of insulation are also considered.

The electric strength of all dielectric media depends on pressure (or pressure and mechanical loads in solid dielectrics), although the nature of this dependence varies. For gases this dependence is due to variations in the number density of neutral particles that are ionized during initiation and evolution of a discharge. At very low residual gas pressures (i.e., in vacuum), the pressure variations can influence near-electrode processes relating to the initiation of vacuum breakdown. For a liquid—an essentially incompressible medium at pressures of tens of megapascals—the effect of pressure on electric strength can be attributed to gas contained in the liquid and concentrated at the electrodes before applying the electric field, newly nucleated bubbles, and products of conduction current electrolysis. An increase in pressure changes the conditions of gas formation, displaces the equilibrium between molecular dissolved gas and gas bubbles toward the former, reduces gas bubble size, and increases gas pressure inside bubbles, thereby hindering the ionization processes. Increased hydrostatic pressure can alter the electrophysical parameters of the leader channel (first and foremost, its electrical conductivity) and, as a consequence, the discharge parameters.

One often fails to achieve high electric strengths of vacuum, compressed gases and gas mixtures, and dielectric liquids to manufacture compact insulation equipment, because the electric strengths of insulation gaps considerably decrease when solid insulation is inserted into them. When solid dielectrics are used as barriers or parts of multilayer insulation systems, their surfaces are perpendicular to the electric field lines and hence the breakdown voltage increases. However, in spacers and base and through insulators, the dielectric surface is often parallel to the electric field vector, and the electric strength of a composite dielectric is much lower than that of individual dielectrics.

Electric field control is aimed at increasing the efficiency of insulation by improving electric field homogeneity. Homogenizing the electric field in the bulk of an insulator and on its surface enables the overall dimensions of insulation systems to be reduced. In this case, the electric field at a solid dielectric surface must not exceed its maximum value on the electrode surface without solid dielectric. This can be achieved by choosing an optimal insulator configuration and using a system of shields and other methods described in the present section.

Contamination of the interelectrode medium and electrodes by free or loosely bound particles reduces their electric strength via several effects, including: a microdischarge between the electrode and an oncoming particle which initiates breakdown between the electrodes in vacuum or gas the collision of a high-velocity particle with an electrode accompanied by the emission of vapor and liquid electrode and particle fragments and plasma structures in vacuum collisions of particles with electrodes that alter electrode microrelief, thereby producing field amplification centers single particles and particle bridges produced when particles enter the strong field region, which distort the field distribution impurity particles in insulating liquids, which influence electrohydrodynamic processes during long-term voltage exposure.

The most important characteristic of insulating materials and media is the short-term electric strength for different breakdown probabilities. Investigations of the short-term electric strength play an important role in optimization of insulation design, its rejection, and comparison of insulating properties of EIM and dielectric media. For single-pulse systems with a very short service lifetime, the short-term pulse electric strength test is the main type of testing. In this regard, it is natural to impose more stringent requirements on the accuracy of these tests, which depends on the optimal choice of electrode system configuration, electrode material and treatment technique, frequency of electrode and dielectric medium replacement, method of voltage application, and experimental data processing algorithm.

Gases, liquids, and solid and hybrid dielectrics in gaps with homogeneous electric fields have the highest breakdown voltages. The breakdown voltage decreases with increasing field inhomogeneity. Insulation gaps with a sharply inhomogeneous asymmetric field, such as tip—plane electrode gap, have the lowest breakdown voltages.

In connection with the fact that dielectric materials used to fabricate various parts of high-voltage electrical equipment systems, nuclear and thermonuclear reactors, and electronic devices often operate in ionizing radiation fluxes, problems of radiation resistance and charging of insulating materials and devices are urgent. The researchers involved in the development of accelerator technology and nuclear power engineering from the outset search for radiation-resistant insulation and structural materials, and develop ways to improve the radiation resistance of novel and conventional materials (by the radiation resistance of materials is meant their ability to maintain their basic properties during and after irradiation). Considerable attention has recently been paid to the study of physical processes in dielectrics, supporting the construction of empirical models and the development of engineering methods for predicting the behavior of dielectrics in ionizing radiation fluxes [168].