8.17 Some Mechanical Principles Introduction Electric power can be transmitted or dis tributed either by means of underground cables or by overhead lines. The underground* cables are rarely used for power transmission due to two main reasons. Firstly, power is generally transmitted over long distances to load centres. Obviously, the installation costs for underground transmission will be very h...

Ignition phenomena of electric wires carrying short-term excess electric currents were investigated in microgravity with experiments and calculations. Microgravity experiments were conducted in 100 m and 50 m drop towers and calculations were carried out with a one dimensional cylindrical coordinate system. The experimental results showed that the limiting oxygen concentration (LOC) under a giv...

Tracking is the main factor which limits the safe working electric stress of insulation in power system applications. Polymer samples have been tested in laboratory conditions according to ASTM D2303 on accelerated inclined plane tracking test. In this paper, a model based on improved Weibull statistics is proposed for estimating the breakdown time of polymeric insulating materials with borax. ...

With the development of power modules for high voltage, temperature, and density, their size is becoming smaller, packaging insulation experiences higher electrical, thermal, mechanical stress. Packaging needs to meet requirement that internal electric field, stress should be as low possible. Focusing on coupling principles optimization design among stresses in module insulation, a multi-object...

Natural ester has been widely studied as an alternative dielectric liquid to mineral oil in recent years. Unsaturated triacylglycerol molecules are the main components of natural ester; therefore, in this paper, we investigate the molecular structure and electronic properties of the triolein molecule, an oleic-type triacylglycerol molecule, as a representative component of natural ester oils. T...

Power transformers are important and expensive components in the electric power system. The knowledge of the actual status of the transformer insulation behavior, load tap changer performance, temperature, and load condition is necessary in order to evaluate the service performance concerning reliability, availability and safety. Systems abnormalities, loading, switching and ambient condition n...

The objective of this paper is to present a simple sensor based on Faraday’s Law together with an integration and amplifying stage and used for measuring fast current pulses. Its behavior in time and frequency is tested by measuring Partial Discharges (PD) in electric insulation systems following the guidelines given in the standard IEC 60270. The measurements are also taken with two other sens...

This paper presents an outline of the handling and recycling of SF6 mixtures in electrical power equipment. It is based on the CIGRE Guide for SF6 mixtures and addresses the application fields of SF6 mixtures in electric power equipment, their insulation and switching performance, the evaluation of their environmental advantage, and the processes and equipment for their environmentally responsi...

the electric tension first overcomes the insulation of the dielectric, and proceeds from that point, in an apparently irregular path, so as to take in other weak points, such as particles of dust floating in air... ...These, and many other phenomena of electrical discharge, are exceedingly important, and when they are better understood they will probably throw great light on the nature of elect...

Similar to AC system, the insulation system of DC system also gets affected. The HVDC station is a challenging environment for measurement of partial discharge level due to very high interference levels caused from the switching of thyristor-controlled converters. There is also significant interference from external air-corona due to high electric stress at the surface of conductors and hardwar...