Single Phase SystemInstantaneous PowerThe instantaneous power in an AC circuit is defined as the product of instantaneous voltage (v) across the element and instantaneous current (i) through the element and is denoted by lower case letter p.Instantaneous Power, $\mathrm{p=v\times\:i}$Since, the values of instantaneous voltage and instantaneous current changes from instant to instant, thus the instantaneous power changes with time. The instantaneous power (p) is measured in watts. The instantaneous power may be positive or negative. A positive instantaneous power means power flows from source to load whereas negative instantaneous power means power flows from load to source.Instantaneous Power FormulaCase 1 – ... Read More

The magnetic flux density is the measure of amount of magnetic flux in each square meter of the magnetic field. Therefore, the magnetic flux density is defined as the magnetic flux passing normally (at 90°) per unit area and is denoted by B, i.e., Magnetic flux density, $$B=\frac{\phi}{A}$$Where, Φ is the magnetic flux, A is area normal (or perpendicular) to flux.The magnetic flux density is a vector quantity i.e. it possesses both magnitude and direction.Unit of Magnetic Flux DensityAs we know, the magnetic flux density is$$B=\frac{\phi}{A}=\frac{Weber}{meter^{2}}=Wb/m^{2}=Tesla(T)$$Therefore, the magnetic flux density is measured 𝑊𝑏/𝑚2 or Tesla (T), named in honour of Nikola ... Read More

Capacitance - DefinitionThe ability of a capacitor to store charge is known as its capacitance. In other word, the capacitance can also be defined as the property of a material by virtue of it opposes the any change in voltage applied across it.Capacitance: FormulaExperimentally, it has been found that, the charge Q stored in a capacitor is directly proportional to the voltage across it, i.e.$$Q\propto\:V$$$$Q=CV$$Where, C is a constant and is called as capacitance of the capacitor.$$\Rightarrow\:C=\frac{Q}{V}$$Thus, the capacitance (C) of a capacitor can also be defined as the ratio of the charge on the either plate to the voltage ... Read More

Electromechanical RelayAn electromechanical relay is a type of relay which function using a magnetic field produced by an electromagnetic coil when a control signal is applied to it. It is called as electromechanical since it has moving contacts in the output circuit which are operated by applying an electrical signal.Electromechanical Relay: Working PrincipleAn electromechanical relay transfers signals between its contacts through a mechanical movement. It has three sections viz. input section, control section and output section.The input section consists of input terminals where a small control signal is to be applied. The control section has an electromagnetic coil which gets energised ... Read More

Electricity tariff is defined as the rate at which electrical energy is supplied to a consumer.Types of Tariff in ElectricityThe commonly used electricity tariffs are as follows −Simple Tariff – When there is a fixed rate per unit of energy consumed, it is known as simple tariff or uniform rate tariff. In case of simple tariff, the price charged per unit is constant i.e. it does not change with increase or decrease in number of units consumed.Flat Rate Tariff – When different types of consumers are charged at different uniform per unit rates, it is known as flat rate tariff. In ... Read More

An electrical power system is a network of interconnected electrical devices, which are used to generate, transmit, distribute and utilise the electrical power.A typical electrical power system has following main components −Generating StationTransmission SystemDistribution SystemElectrical LoadGenerating StationIn the single line diagram, the GS represents the generating station where electrical power is produced by three-phase parallel connected alternators. The usual generation voltage is 11 kV (in India). For economic considerations the generation voltage is stepped up to high voltages (say 132 kV) using 3-phase transformers for the transmission.Transmission SystemThe electrical transmission system is divided into two types depending on the voltage ... Read More

The voltage levels or voltage ratings are defined and classified by various national and international standards and also by some electrical utility companies.In general, an electrical professional comes across the terms LV / LT, MV, HV / HT, EHV / EHT and UHV in our day-to-day professional lives.Voltage Rating StandardsThe Indian Electricity Rules, 1956, the following were the voltage limits of power system and equipment −Low Voltage (LV) − Less than or equal to 250 V.Medium Voltage (MV) − Less than or equal to 650 V.High Voltage (HV) − Less than 33 kV.Extra-High Voltage (EHV) − More than 33 kV.However, ... Read More

What is a Distribution System?The part of the power system that distributes electric power for local use is called as distribution system. Generally, a distribution system is the electrical system between the substation fed by transmission system and the consumer’s meters. A typical distribution system is shown in the figure.Components of Distribution SystemDistribution Sub-Station – A distribution sub-station is the electrical system which transfers power from transmission system to the distribution system of an area.Feeders – A feeder is a conductor which connects the distribution sub-station to the area where power is to be distributed. The current in a feeder remains ... Read More

Capacitor & CapacitanceWhen any two conducting surfaces are separated by an insulating material, it called as a capacitor. The conducting surfaces are known as plates of the capacitor and the insulating material is known as dielectric.The ability of a capacitor to store charge is termed as capacitance of the capacitor. It is denoted by C and measured in Farad (F).By experiments, it has been found that charge (Q) stored in a capacitor is directly proportional to the potential difference across it, i.e., $$Q\varpropto\:V$$$$\Rightarrow\:Q=CV$$$$\Rightarrow\:C=\frac{Q}{V}\:\:\:\:...(1)$$Where, C is a constant, known as capacitance of the capacitor.Hence, the capacitance (C) of a capacitor is ... Read More

Capacitors can be classified depending upon their fixed or variable capacitance as follows −Fixed CapacitorsThose capacitors whose value of capacitance is fixed during the manufacturing and cannot be changed later are known as fixed capacitors. The symbol of the fixed capacitor is shown in figure.The fixed capacitors are classified into two categories as −Polarized CapacitorsNon-Polarized CapacitorsPolarized CapacitorsThose capacitors which are having the specified positive and negative polarities, are called as polarized capacitors. When these capacitors are used in the circuits, they should be connected in perfect polarities.Polarized capacitors are further classified as −Electrolytic CapacitorsThose capacitors in which some electrolyte is ... Read More