Protection of Transmission Lines The probability of faults occurring on the lines is much more due to their greater length and exposure to atmospheric conditions. This has called for many protective schemes which have no application to the comparatively simple cases of alternators and transformers. The requirements of line protection are:- The protection of lines […]
3-Phase Transformer Protection Schemes Transformers are static devices, totally enclosed and generally oil immersed. Therefore, chances of faults occurring on them are very rare. However, the consequences of even a rare fault may be very serious unless the transformer is quickly disconnected from the system. This necessitates to provide adequate automatic protection for transformers against
Types of Functional Relays Most of the relays in service on power system today operate on the principle of electromagnetic attraction or electromagnetic induction. Regardless of the principle involved, relays are generally classified according to the function they are called upon to perform in the protection of electric power circuits. For example, a relay which
Types of Protective Relays In a power system consisting of generators, transformers, transmission and distribution circuits, it is inevitable that sooner or later some failure will occur somewhere in the system. When a failure occurs on any part of the system, it must be quickly detected and disconnected from the system. There are two principal
Bus Bar Arrangement in Substation When a number of generators or feeders operating at the same voltage have to be directly connected electrically, bus-bars are used as the common electrical component. Bus-bars are copper rods or thin walled tubes and operate at constant voltage. In this article, we shall discuss some important bus-bars arrangements used
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
Lightning or surge arresters serve the same purpose on an electric circuit or line as a safety valve on a boiler. A safety valve on a boiler relieves a high pressure by allowing steam to blow off until the high pressure is reduced to normal, at which time the safety valve closes again and is
Generally, it can be stated that a circuit breaker is intended to protect the electrical conductors in the circuit from overheating. It can also be stated that the equipment grounding conductor (EGC) is required by the NEC to be connected so that a low impedance fault current path is provided for the main purpose of