A conventional two-winding transformer can be converted into an autotransformer as shown in the figures given below. It can be converted into a step-up autotransformer by connecting the two windings electrically in series with additive polarities. If the windings are connected electrically in series with subtractive polarities, then a step-down ... Read More

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 ... 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 ... 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 ... 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 ... 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 ... 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 ... 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 ... 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 ... 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 ... Read More