Overvoltage Protection

When the voltage in a system, raised beyond its rated voltage, then it is known as overvoltage. This overvoltage may be of transient or persistent nature. The main cause due to which overvoltage is produced in the power system may be conveniently grouped into two categories, namely, internal and external. Internal overvoltage has got their …

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Power Factor

The power factor is defined as the ratio of the active power (P) and volt-amperes. The active power is the real power which is assumed in an AC circuit, whereas volt-amperes is the apparent power which is produced in the circuit when the waves of voltage or current are not in phase. For sinusoidal waveforms, …

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Power Factor Improvement

If the power factor is low or poor, it is necessary to improve or correct it. It may be improved by injecting a leading current into the circuit so as to neutralize the effect of lagging current. The power factor may be improved by using static capacitors or synchronous motors. Power factor correction by static …

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Solid Grounding

A power system is said to be effectively grounded or solidly grounded when the neutral of a generator, power transformer or grounding transformer are directly connected to the ground through a conductor of negligible resistance and reactance. A part of a system or system is said to be solidly grounded when the positive-sequence impedance of …

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Calculation of Sag & Tension

Calculation of sag and tension in transmission line depend on the span of the conductor. Span having equal level supports is called level span, whereas when the level of the supports is not at an equal level is known as unequal level span. The calculation of conductor at an equal level shown below. Consider a …

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Sag and Tension

For safety purpose, the ground clearance of the conductors at maximum temperature and minimum loading condition should be maintained. Analysis of the sag and tension is important in the transmission line for the continuity and quality of electrical services. If the tension of the conductor is increased beyond the limit, it may get broken, and …

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Swing Equation

The transient stability of the system can be determined by the help of the swing equation. Let θ be the angular position of the rotor at any instant t. θ  is continuously changing with time, and it is convenient to measure it with respect to the reference axis shown in the figure below. The angular position …

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Power System Stability

Power system consists some synchronous machines operating in synchronism. For the continuity of the power system, it is necessary that they should maintain perfect synchronism under all steady state conditions. When the disturbance occurs in the system, the system develops a force due to which it becomes normal or stable. The ability of the power …

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Power-Angle Curve

Consider a synchronous machine connected to an infinite bus through a transmission line of reactance Xl shown in a figure below. Let us assume that the resistance and capacitance are neglected. Equivalent diagram of synchronous machine connected to an infinite bus through a transmission line of series reactance Xl is shown below: Let, V = V<0⁰ …

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Capacity Factor

The capacity factor is defined as the ratio of the total actual energy produced or supply over a definite period, to the energy that would have been produced if the plant (generating unit) had operated continuously at the maximum rating. The capacity factor mainly depends on the type of the fuel used in the circuit. The capacity …

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