Apparatus Protection in Power System

Bus Zone Protection

Bus Zone Protection: Bus Zone Protection includes, besides the bus itself the apparatus such as circuit breakers, disconnecting switches, instrument transformers and bus sectionalizing reactors, etc. Although bus zone faults are rare, experience shows that bus zone protection is highly desirable in large and important stations. Bus zone is more vulnerable to the effects of …

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Direct Connected Generator Protection

Direct Connected Generator Protection: Direct connected generators are normally of smaller ratings and a typical scheme of Direct Connected Generator Protection for a 30 MW generator is shown in Fig. (6.21). It consists of the following protections: Unbiased differential protection. Backup overcurrent protection. Negative phase sequence protection. Standby earth fault. In addition to these protections …

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Overload Protection Relay

Overload Protection Relay: Overload Protection Relay – Continuous balanced overloading of a machine causes overheating in the stator winding. An obvious solution to this is the application of overcurrent relays; but this is not usually provided because this discriminates by time, it must be arranged to discriminate with the slowest relay on the system which …

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Unbalanced Loading Protection of Generator

Unbalanced Loading Protection of Generator: Unbalanced Loading Protection of Generator – Whatever be the cause of the unbalance it is obvious that the negative phase sequence current will result in heating of the stator. In case of high-speed turbo-generators, the continuous current which can be carried is usually between 10 and 15% of the positive …

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Loss of Excitation Protection

Loss of Excitation Protection: Two distinct effects of Loss of Excitation Protection are that the machine starts drawing magnetizing current of large magnitude from the system, and the slip frequency emfs induced in the rotor circuit; both of them cause over¬≠heating of the rotor. Loss of Excitation Protection can be detected by measuring the reactive …

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Generator Faults

Generator Faults: Generator faults can be considered under the following heads. (a) Stator Faults: These include the following: Phase-to-earth faults. Phase-to-phase faults. Inter-turn faults. Most faults occur in the stator windings and their connections and majority of these are earth faults. Phase faults and inter-turn faults an less common, these usually develop into an earth …

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