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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Neutral Grounding

In neutral grounding system, the neutral of the system or rotating system or transformer is connected to the ground. The neutral grounding is an important aspect of power system design because the performance of the system regarding short circuits, stability, protection, etc., is greatly affected by the condition of the neutral. A three phase system …

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Resistance & Reactance Grounding

Resistance grounding In this type of  neutral grounding, the neutral of the system is connected to ground through one or more resistance. Resistance grounding limits the fault currents. It protects the system from transient overvoltages. Resistance grounding decreases the arcing grounding risk and permits ground-fault protection. The value of resistance used in the neutral grounding …

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Types of Electrical Insulator

Overhead line insulators are used to separate line conductors from each other and the supporting structures electrically. Permittivity and dielectric strength of the insulating material are very high so that it can withstand high electrical stress. Insulators protect the transmission line from overvoltages which occur due to lightning,  switching, or other causes under the severe …

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Tap-changing Transformers

The change of voltage is affected by changing the numbers of turns of the transformer provided with taps. For sufficiently close control of voltage, taps are usually provided on the high voltage windings of the transformer. There are two types of tap-changing transformers Off-load tap changing transformer On-load tap changing transformer Off-load tap-changing transformer In …

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