Booster Transformer

Booster transformer is one which is often used towards the end of a power line to raise the voltage to the desired value. It is used for controlling the voltage of a feeder at a point far away from the main transformer. The secondary of the booster transformer is connected in series with the line, …

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Static VAR Compensator

A static VAR compensator is a parallel combination of controlled reactor and fixed shunt capacitor shown in the figure below. The thyristor switch assembly in the SVC controls the reactor. The firing angle of the thyristor controls the voltage across the inductor and thus the current flowing through the inductor. In this way, the reactive …

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Potential Gradient

The potential gradient in a power system is defined as the rate of change of electric potential with respect to the distance from the base of the electrical structure. The resistance of the earth electrode is not concentrated at one point, but it is distributed over the soil around the electrode. When a fault current …

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Symmetrical Components

When the system is unbalanced the voltages, currents and the phase impedances are in general unequal. Such a system can be solved by a symmetrical per phase technique, known as the method of symmetrical components. This method is also called a three-component method. The method of symmetrical components simplified the problems of the unbalanced three-phase …

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Short Circuit Current

When two or more conductors of different phases come in contact with each other in a power line, power transformer or any other power element, then the part of the impedance is shunted out of the circuit due to which a large current flow in the un-faulted phases, such current is called the short circuit …

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Peterson Coil Grounding

Peterson coil is an iron core reactor connected between transformer neutral and ground. It is used for limiting the capacitance earth fault current which is flowing when the line ground fault occurs in the line. The coil is provided with the tapping so that it can be adjusted with the capacitance of the system. The …

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Zig-Zag Transformer

A zig-zag transformer is used for providing grounding on the transformer. It provides insulation between the ground and the component so that the system component may not be affected by the fault currents. Zigzag transformer terminates the harmonics of the power system. It also protects the power system by reducing the stress of the voltage under …

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Grounding Transformer

The grounding transformer is used to provide a path to an ungrounded system or when the system neutral is not available for some reason, for example, when a system is delta connected. It provides a low impedance path to the neutral and also limits the transient overvoltage when the ground faults occur in the system. …

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Line-to-Line Fault

A line to line fault or unsymmetrical fault occurs when two conductors are short circuited. In the figure shown below shows a three phase system with a line-to-line fault phases b and c. The fault impedance is assumed to be Zf. The LL fault is placed between lines b and c so that the fault …

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