Protective Relaying Principles and Applications

The applications of the different types of protection systems for the protection of various types of equipment and transmission lines are described in this section. These discussions are confined to protection for the high-voltage, bulk-power system components. Generator Protection The protection system provided to the synchronous generator must be able …

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Swing Equation in Power System

Swing Equation The motion of a synchronous machine is governed by Newton’s law of rotation, which states that the product of the moment of inertia times the angular acceleration is equal to the net accelerating torque. Mathematically, this may be expressed as follows: $\begin{matrix}   J\alpha ={{T}_{a}}={{T}_{m}}-{{T}_{e}} & {} & \left( …

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Transient Stability in Power System

Power system stability refers to the ability of the various synchronous machines in the system to remain in synchronism or stay in step, with each other following a disturbance. Stability may be classified as steady-state, dynamic, or transient stability. Steady-state stability refers to the ability of the various machines to …

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Types of Protective Relays

The protective relay is the device that responds to signals from the transducers by quickly initiating or allowing a control action to be implemented in order to prevent damage to the faulted equipment and to restore service as soon as possible. The operating characteristics of the more commonly used protective …

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Power System Protection Components

power system protection components

The operation of a power system is affected by disturbances that could be due to natural occurrences such as lightning, wind, trees, animals, and human errors or accidents. These disturbances could lead to abnormal system conditions such as short circuits, overloads, and open circuits. Short circuits, which are also referred …

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Symmetrical Components in Power System

sequence components of voltages

The method of symmetrical components is used to solve power system problems involving unbalanced polyphase voltages and currents. It is analogous to the Fourier analysis of nonsinusoidal wave shapes wherein a non-sine wave is resolved into a number of sine waves of various frequencies. In symmetrical components, the unbalanced set …

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Electrical Power System Components

power system

The electrical power system can be divided into three major components: generation (G), transmission (T), and distribution (D) as shown in Fig. 1. The generating system provides the system with electric energy. Transmission and Sub-Transmission Systems The transmission and sub-transmission systems are meshed networks; that is, there is more than …

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Analog Multimeter Working Principle

Taking a reading with an analog multimeter

An analog multimeter is a meter that can measure two or more electrical properties and display the measured properties along calibrated scales using a pointer. Analog multimeter uses an electromechanical component called a D’Arsonval movement to move the pointer along the scales to display measured values when the test leads …

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Three-Phase AC Generator Working

3-phase revolving-armature generator

There are two basic types of 3-phase generators (alternating-current generators): (1) the revolving-armature type (Figure 1) and (2) the revolving-field type (Figure 2).  The 3-phase revolving-armature generator rotates the three single-phase windings, located 120 mechanical degrees apart on the rotor assembly, around the inside of a fixed or stationary electromagnetic …

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Three-Phase AC Power Calculation

Power relationships in an AC circuit

In a three-phase AC power distribution circuit, three single-phase AC sources are interconnected in either a wye or delta configuration to form a 3-wire supply in the alternator, transformer, or electric motor, and sometimes a 4-wire supply in the alternator or transformer. If the three single-phase AC sources were in-phase …

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Three-Phase AC Power: Star & Delta Connection

Generation of three single-phase AC

The most economical way to mass produce AC power is by steam turbines that drive large three-phase AC generators (alternators — Figure 1). Figure 1. Steam turbines drive large 3-phase AC generators This is why most electrical-utility power generating plants are located on a river that has been dammed to …

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Single-Phase AC Power

Generation of single-phase AC power

In a single-phase (or 3-phase for that matter) AC electrical power distribution system, both the load current (as electrical utilization loads are connected) and the applied voltage that causes it to flow are transmitted along the length of the circuit conductors varying in amplitude with time and periodically reverse between …

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