Found 1006 Articles for Electronics & Electrical

Power FactorThe cosine of angle between voltage and current in an AC circuit is called the power factor of the circuit. In other words, the power factor is defined as the ratio of active power to the apparent power in the circuit, i.e., $$\mathrm{Power\: factor, cos\:\phi\:=\:\frac{Active\: power\: (in \:Watts)}{Apparent\: power\: (in\: VA)}}$$Where, $\phi$ is the power factor angle.Causes of Low Power FactorFrom the economic point of view, the low power factor of the load connected to a power system is undesirable. The main causes of low power factor are given as follows −The AC electric motors consist of inductive winding. ... Read More

The useful output of a power generating station is the kW output which is delivered by the station to the electrical supply system. Sometimes, a power generating station needs to deliver more kW to meet the increased power demand. This can be achieved by any of the following two methods −By increasing kVA capacity – In this method, the kVA capacity of the power generating station is increased at the same power factor to meet the increased kW demand. Although, this causes extra cost to increase the kVA capacity of the power station.By improving power factor – In this method, ... Read More

Most Economical Power FactorThe value to which the power factor should be improved so as to have maximum net annual saving is called the most economical power factor.When a consumer improves the power factor, it results in reduction in his maximum kVA demand. Consequently, there will be an annual saving over the maximum demand charges. Although the power factor improvement involves the capital investment on the power factor correction equipment, the consumer will draw expenditure every year in the shape of annual interest and depreciation on the investment made over equipment used for power factor correction. Hence, the net annual ... Read More

Depreciation of Power Plant EquipmentThe reduction in the value of the equipment and other property of the power station every year is known as depreciation. Therefore, a suitable amount, called depreciation charge, must be set aside annually so that by the time the life span of the power plant is over, the collected amount equals to the cost of the replacement of the power plant.Straight Line Method of DepreciationIn the straight line method of calculating depreciation, a constant depreciation charge is made every year on the basis of total depreciation and the useful life of the equipment or other property. ... Read More

The cost of conductor material required for designing a transmission line is a very considerable part of the total cost of a transmission line. Therefore, the determination of proper size of the conductor for the transmission line is very important. The proper size of the conductor for transmission line is determined by the Kelvin’s law (given by Lord Kelvin in 1881).The Kelvin’s law states that the most economical area of conductor is that for which the total annual cost of transmission line is minimum.The total annual cost of the transmission line can be divided into two parts viz. −Annual charges ... Read More

Depreciation of Power Plant EquipmentThe reduction in the value of the equipment and other property of the power station every year is known as depreciation. Therefore, a suitable amount, called depreciation charge, must be set aside annually so that by the time the life span of the power plant is over, the collected amount equals to the cost of the replacement of the power plant.Diminishing Value Method of DepreciationIn the diminishing value method for calculating the depreciation, the depreciation charge is made every year at a fixed rate on the diminished value of the equipment, i.e. the depreciation charge is ... Read More

Overhead DC Transmission SystemThe overhead transmission system is the one in which the conductors are hanged with the help of pole supports. When the transmission lines carry direct current, then the system is called the DC transmission system.There are three types of overhead DC transmission systems viz. −Two wire DC system with one conductor earthedTwo wire DC system with mid-point earthedThree wire DC systemConductor Material Required in Two-Wire DC System with One Conductor EarthedConsider a two wire DC system with one conductor earthed as shown in Figure-1. Here, one is the positive wire and the other is the negative wire ... Read More

Two Phase AC Transmission SystemWhen the transmission system consists of two line conductors for the transmission of AC electric power from generating station to the substations for its distribution, it is called the two phase AC transmission system.Depending upon the number of conductors used, the two phase AC transmission system is of two types, viz. −Two Phase Three Wire AC SystemTwo Phase Four Wire AC SystemConductor Material Required in Two Phase Three Wire AC SystemConsider a two-phase three-wire AC system as shown in Figure-1.There are two line conductors and one neutral wire is taken from the junction of two-phase windings ... Read More

Power Plant or Power StationA power plant or power station or generating station is an industrial facility for the generation of electrical power.A typical generating station or power plant consists of a prime mover (ex. steam turbine, water turbine, etc.) which is coupled to an alternator. The prime mover converts the energy from some source (ex. coal, water, radioactive materials, etc.) into mechanical energy. The alternator converts mechanical energy of the prime mover into electrical energy. The electrical energy produced by the alternator is transmitted and distributed with the help of conductors to the consumers.Apart from the prime mover and ... Read More

Load CurvesThe graph which shows the variation of load on the power station with respect to time is called the load curve of the power station.The load on a power station does not remain constant; it changes from time to time. These changes in the load on a power station during whole day (i.e. for 24 hours) are recorded half-hourly or hourly and are plotted with respect to time on the graph. The obtained graph is called the daily load curve of the power plant.The daily load curve shows the variation of load with respect to time during the day. ... Read More