Depreciation of Power Station 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.Sinking Fund Method of DepreciationIn the sinking fund method of depreciation, a fixed depreciation charge is made every year and the interest is compounded on it annually. The constant depreciation charge is such that the sum ... Read More

Units of EnergyThe capability of an object to do work is called its energy. In electrical engineering, the most important forms of energy are electrical energy, mechanical energy and thermal energy. Different units of measurement are used for the various forms of energy. Although, the units of electrical, mechanical and thermal energies are interchangeable.The units of various forms of energy are described as follows −Mechanical EnergyThe mechanical energy is defined as the product of force and distance, i.e., $$\mathrm{\mathrm{Mechanical \:energy\:=\:Force\: in \:Newton\:\times \:distance\: in \:meters}}$$Therefore, the SI unit of mechanical energy is Newton-meter (Nm) or Joules (J).The mechanical energy of ... Read More

Advantages of High Transmission VoltageElectric power is transmitted at very high voltages due to some technical and economic reasons which are described as follows −1. Reduces the Volume of Conductor MaterialConsider the electric power being transmitting through the three-phase three-wire transmission system.Let, P = Power transmitted (in Watts)V = Line voltage (in Volts)$\mathrm{cos}\:\phi$ = Load power factorR = Resistance per conductor (in ohms)$\mathit{\rho}$ = Resistivity of conductor materiall = length of transmission line (in meters)a = cross sectional area of conductorTherefore, the load current is given by, $$\mathrm{\mathit{I}\:=\:\frac{\mathit{P}}{\sqrt{3}\mathit{V}\mathrm{cos\:\phi }}}$$And the resistance per conductor is$$\mathrm{\mathit{R}\:=\:\rho \:\frac{\mathit{l}}{\mathit{a}}}$$Thus, the total power loss in ... Read More

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., $$\mathrm{\mathrm{Power\: factor, }\:\mathrm{cos}\:\phi \:=\:\frac{\mathrm{Active\: power\: (in\: Watts)}}{\mathrm{Apparent\: power \:(in\: VA)}}}$$Where, $\phi$ is the power factor angle.In an AC circuit, there may be a phase difference ($\phi$) between voltage and current. The term cos $\phi$ is called the power factor of the circuit.When the given circuit is inductive, then the current lags behind the voltage and the power ... Read More

Connected LoadThe connected load is defined as the sum of continuous ratings of all the equipment connected to the electrical power station.An electric power station supplies the power to thousands of consumers. Each consumer has certain equipment in his premises. The sum of the continuous ratings of all the equipment in the consumer’s premises is the connected load of the consumer. The sum of the connected loads of all the consumers is called the connected load to the power station.Average LoadThe average load on a power station is defined as the average of loads occurring on the power station in ... Read More

A power plant converts one form of energy (for example, hydro, thermal, nuclear, etc.) to electrical energy. We can broadly classify the power plants as follows −Thermal Power PlantHydroelectric Power PlantNuclear Power PlantDiesel Power PlantIn addition, there can be other types of power plants such as Solar Power Plant and Wind Power Plant, but these type of power plants are so far insignificant in terms of capacity and utilization.In this article, we will compare and contrast the different attributes of thermal, hydroelectric, nuclear, and diesel power plantsThermal Power PlantA Thermal Power Plant is a generating station which converts heat energy ... Read More

The electric power can be transmitted either by using AC transmission system or DC transmission system. Each transmission system has its own advantages and disadvantages. Therefore, to choose the right system for electric power transmission, we need to compare the two systems.The following table compares and contrasts the AC transmission system and DC transmission system based on different parameters −ParameterAC Transmission SystemDC Transmission SystemDefinitionAn electric power transmission system that uses alternating current to transmit the power is called the AC transmission system.An electric power transmission system which transmits the electric power in the form of DC supply, is called the ... Read More

Cost of Electrical EnergyThe cost of electrical energy generated can be divided into three parts, viz −Fixed CostSemi-Fixed CostOperating or Running CostFixed Cost of Electrical EnergyThe cost of electrical energy generated which is independent of the units generated and the maximum demand, is known as fixed cost.The fixed cost of electrical energy is mainly due to the annual cost of central organisation, interest on capital cost of land and the salaries of high officials. The annual cost of the central organisation and the salaries of high officials is fixed, it is because, it has to be met whether the power ... Read More

Demand FactorThe demand factor of an electric power station is defined as the ratio of maximum demand on the power station to its connected load, i.e., $$\mathrm{Demand \:Factor\:=\:\frac{Maximum\: Demand}{Connected \:Load}}$$Generally, the value of demand factor is less than 1. It is because the maximum demand on the power station is usually less than the connected load to the power station. The knowledge of demand factor is important in determining the capacity of equipment of the power plant.Numerical Example (1)A generating station has a connected load of 50 MW and a maximum demand of 30 MW. Determine the demand factor of ... Read More

Units Generated per AnnumThe kWh generated per annum or the energy generated per annum by a power station is determined as follows −$$\mathrm{\because Load\: factor\:=\:\frac{Average\: load}{Maximum\: demand}}$$$$\mathrm{\therefore Average\: load\:=\:Maximum\: demand\:\times \:Load\: factor}$$Hence, the units generated per annum is given by, $$\mathrm{Units\: generated \:per \:annum\:=\:Average\: load \:in\: kW\:\times \:Hours \:in\: a\: year}$$$$\mathrm{=\:Maximum\: demand\: in\: kW\:\times \:Load\: factor\:\times\: 8760}$$$$\mathrm{\Rightarrow Units\: generated\: per\: annum\:=\:Maximum\: demand \:in\: kW\:\times \:Load\: factor\:\times \:8760}$$Plant Capacity FactorThe plant capacity factor of a power station is defined as the ratio of actual energy produced to the maximum possible energy that could have been produced during a given period, i.e., ... Read More