Restriking Voltage Transient: Electrically a power system is an oscillatory network so that it is logical to expect that the interruption of fault current will give rise to a transient, whose frequency depends on the constants of the circuit. It has been pointed out earlier that this transient voltage is referred to as Restriking Voltage […]
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Recovery Voltage: Recovery Voltage – While closing or opening the circuit breaker, the circuit constants play an important role. It was noticed in practice a circuit breaker that would operate satisfactorily at one point on a system may not do so at another, showing that the circuit conditions have some influence on the circuit breaker
Circuit Breaker Rating: The ratings of a circuit breaker refer to the characteristic values that define the working conditions for which the circuit breaker is designed and built. Circuit breakers must be capable of carrying continuously the full load current, without excessive temperature rise, and should be capable of withstanding the electrodynamic forces. The circuit
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Arc Interruption Methods in Circuit Breakers: The two modes of Arc Interruption Methods in Circuit Breakers are: high resistance interruption, and low resistance or current zero interruption. High Resistance Interruption: In this case the arc is controlled in such a way that its effective resistance increases with time so that the current is reduced to
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Arc Properties: The manner in which the are medium is made to conduct has already been studied. A plot of instantaneous values of voltage eB between the electrodes of a burning arc against the corresponding values of current gives the Arc Properties. With the increase of arc current the temperature rises and the process of ionization
Arc in Circuit Breaker: Discharge in a.c. circuit breakers, generally in the form of an arc, occurs in two ways. When the contacts are being separated arcing is possible even when the circuit emf is considerably below the minimum cold electrode breakdown voltage, because of the large local increase in voltage due to the circuit
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Static Distance Protection Relay: Static Distance Protection Relay are characterized by having two input quantities respectively proportional to the voltage and current at a particular point in the power system, referred to as the relaying point. The ideal forms of such relays have characteristics which are not dependent on the actual values of voltage and
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Differential Protection Relay in Power System: A Differential Protection Relay in Power System scheme compares quantities derived from the input and output currents of the protected circuit in such a manner that, for all healthy system and through fault conditions, the quantities balance and the protection is inoperative, while for internal fault conditions the balance
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Overcurrent Protection Relay in Power System: The technique of Overcurrent Protection Relay in Power System is still widely used as a means of detecting faults on distribution system and on transmission lines fed from one end. In the case of lines fed from both the ends it is used along, with directional relays. Overcurrent Protection
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Basic Elements of Static Relay: The basic elements of a static relay are namely, Input Element: Mixing circuits are needed to sum the input signals in a convenient form. Semiconductor circuits are suited to the use of summing junctions, well-known in the analog computing field. Use of operational amplifier as a summer or mixer has
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