Protection of Transmission lines by Ground Wires The ground wire is a conductor running parallel to the power conductors of the transmission line and is placed at the top of the tower structure supporting the power conductors (Fig. 1). For the horizontal configuration of the power line conductors, there are two ground wires to provide […]
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Insulation coordination of Electrical Equipment Insulation coordination means the correlation of the insulation of the various equipment in a power system to the insulation of the protective devices used for the protection of those equipment against overvoltages. In a power system, various equipment like transformers, circuit breakers, bus supports, etc. have different breakdown voltages and
Overvoltage Protection by Lightning Arresters There are two sources of overvoltages in the power system: The system can be protected against external overvoltages using what are known as shielding methods which do not allow an arc path to form between the line conductors and ground, thereby giving inherent protection in the line design. For protection
Testing of Power Capacitors Power capacitors are an integral part of the modern power system. These are used to control the voltage profile of the system. The following tests are carried out on shunt power capacitors (IS 2834): Routine Tests Routine tests are carried out on all capacitors at the manufacturer’s premises. During testing, the
Testing of Circuit Breakers An equipment when designed to certain specifications and is fabricated, needs testing for its performance. The general design is tried and the results of such tests are conducted on one selected breaker and are thus applicable to all others of identical construction. These tests are called the type tests. These tests
Testing of Transformer A transformer is one of the most expensive and important equipment in the power system. If it is not suitably designed its failure may cause a lengthy and costly outage. Therefore, it is very important to be cautious while designing its insulation, so that it can withstand transient over voltage both due
Testing of Cables High voltage power cables have proved quite useful, especially in the case of HV d.c. transmission. Underground distribution using cables not only adds to the aesthetic looks of a metropolitan city but it provides better environments and more reliable supply to the consumers. Preparation of Cable Sample The cable sample has to
Testing of Overhead Line Insulators Various types of overhead line insulators are (i) Pin type (ii) Post type (iii) String insulator unit (iv) Suspension insulator string (v) Tension insulator. Arrangement of Insulators for Test The string insulator unit should be hung by a suspension eye from an earthed metal cross arm. The test voltage is
Applications of Insulating Materials Insulating fluids (gases and liquids) provide insulation between phases and between phase and grounded parts of electrical equipment. These also carry out heat from the windings of the electrical equipment. However, solid insulating materials are used only to provide insulation. While describing the dielectric and other properties of various insulating materials,
Properties of Insulating Materials The main requirements of the insulating materials used for power apparatus are: Vulcanized Rubber Rubber in its natural form is highly insulating but it absorbs moisture readily and gets oxidized into a resinous material; thereby it loses insulating properties. When it is mixed with sulfur along with other carefully chosen ingredients