Found 1006 Articles for Electronics & Electrical

A full-load test on the large transformer is to be conducted to determine the maximum temperature rise of the transformer which is called as back-to-back test. The back-to-back test is also known as Sumpner’s test or regenerative test.In case of small transformers, the full-load test is conveniently possible, but for large transformers, full load test is very difficult. It is because, a suitable load to consume full-load power of a large transformer may not be available. It will also be very expensive as a large amount of energy will be wasted in the load during the test.The figure shows the ... Read More

Approximate Voltage Drop in a TransformerThe figure shows the approximate equivalent circuit of a practical transformer referred to secondary side.At no-load i.e. with I2= 0, the secondary terminal voltage is, $$\mathrm{V_{2}=KV_{1} .....(1)}$$When an inductive load of power factor cosφ2 (lagging) is connected across the secondary winding of the transformer, the secondary winding carries a current I2 and hence the voltage drops occur in $(R_{2} + K^2R_{1})$ and $(X_{2} + K^2X_{1})$. As a result, the secondary voltage drops from KV1 to V2 across the load terminals.By applying KVL to the circuit, we get, $$\mathrm{V_{2}=KV_{1}-I_{2}[(R_{2} + K^2R_{1})+J(X_{2} + K^2X_{1})]}$$$$\mathrm{⇒ V_{2}=KV_{1}-I_{2}(R_{02} +jX_{02}) = ... Read More

There are different types of DC generators are available for the various types of applications. The applications of various types of DC generators based on their characteristics are as follows −Applications of Separately Excited DC GeneratorsA separately excited DC generator requires an independent external DC source for the excitation of field winding. Thus, it is expensive and being rarely used. Following are some application of separately excited DC generators −These are able to produce a wide range of voltage output, they are primarily used in laboratory and commercial testing.These are used in speed regulation tests.These generators operate in a stable ... Read More

The currents induced in the armature winding of a DC generator are alternating in nature. The action of commutator (called commutation) involves the change from a generated alternating current to a direct current.ExplanationConsider a commutator consisting of a cylindrical metal ring cut into two segments C1 and C2 respectively separated by a thin sheet of mica. The commutator is mounted on the rotor shaft and insulated from it. The ends of the armature coil sides AB and CD are connected to the segments C1 and C2 respectively. Two stationary carbon brushes are placed on the commutator and carry current to ... Read More

Magnetic Leakage or Leakage FluxThe part of magnetic flux that does not follow the desired path in a magnetic circuit is known as leakage flux.In most of practical magnetic circuits, the path of a large part of the magnetic flux is through iron part of the magnetic circuit and the rest part of magnetic flux flows through air. The magnetic flux in the air gap is known as useful flux $(\varphi_{g})$ since it can be used for various useful purposes.Consider a magnetic circuit having an iron core with a coil wound on it and having a narrow air gap. The ... Read More

What is a Smart Grid?A smart grid is a digitally enabled electrical grid that collects, distributes and works on the information about the behaviour of all suppliers and consumers in order to improve the efficiency, reliability and sustainability of electricity service.Smart Grid = Information Technology + Electrical GridThe smart grid uses a two-way digital communication of technologies and computer processing which enables electricity industry to better manage energy delivery and transmission. It is capable of providing real time information and enable the nearby quick balancing of supply and demand.How does a Smart Grid Work?In addition to the traditional grid’s generating ... Read More

A singly-excited system is type of excitation system used in electromechanical energy conversion which requires only one coil to produce the magnetic field. In the singly-excited system, there is only one set of electrical input terminals and one set of mechanical output terminals. The examples of singly-excited system are electromagnetic relay, hysteresis motor, solenoid valve etc.In a singly excited system, a coil is wound around a magnetic core and is connected to a voltage source so that it produces a magnetic field. Due to this magnetic field, the rotor which is made up of ferromagnetic material, experiences a torque urging ... Read More

A DC generator is an electrical machine which converts mechanical energy into DC electrical energy. DC generators are classified into two types on the basis of their methods of field excitation as follows −Separately Excited DC GeneratorSelf-Excited DC GeneratorSeparately Excited DC GeneratorA separately excited DC generator is the one whose field winding is supplied by an independent external DC source (like a battery). The magnitude of generated voltage depends upon the speed of rotation of armature and the field current, i.e., greater the speed and the field current, higher is the generated voltage. In practice, the separately excited DC generators ... Read More

AC generators are commonly known as synchronous generators or alternators which convert mechanical power into AC power. The term alternator is used for AC generator because it produces AC power. Also, it is called synchronous generator because it must be driven at a constant speed (equal to synchronous speed) to generate AC power of the desired frequency.In general, two types of AC generators are used in practice −Single Phase AC GeneratorThree Phase AC GeneratorSingle Phase AC GeneratorA single phase AC generator is an electric machine that converts mechanical power into 1- phase electric power (AC) through the process of electromagnetic ... Read More

A device which converts electrical energy into mechanical energy or mechanical energy into electrical energy is known as electromechanical energy conversion device.The electromechanical energy conversion takes place through the medium of a magnetic field. The magnetic field is used as a coupling medium between electrical and mechanical systems. It is because the energy storing capacity of a magnetic field is very high. Therefore, an electromechanical energy converter has three main parts −Mechanical systemCoupling mediumElectrical systemThe electromechanical energy converters are of two types −Gross-motion devices − Such as electrical motors or generators.Incremental motion devices − Such as microphones, loudspeakers, electromagnetic relays ... Read More