# Electrical Machines

## Shaft Torque

In a DC Motor, the complete electromagnetic torque (T) developed in the armature is not available on the shaft. This is so because a part of it is lost to overcome the iron and mechanical (friction and windage) losses. Therefore, shaft torque (Tsh) is somewhat less than the torque developed in the armature. Thus, in …

## Torque Equation of a DC Motor

When a DC machine is loaded either as a motor or as a generator, the rotor conductors carry current. These conductors lie in the magnetic field of the air gap. Thus, each conductor experiences a force. The conductors lie near the surface of the rotor at a common radius from its centre. Hence, a torque …

## Working Principle of a DC Motor

The DC motor is the device which converts the direct current into the mechanical work. It works on the principle of Lorentz Law, which states that “the current-carrying conductor placed in a magnetic and electric field experience a force”.  The experienced force is called the Lorentz force. The Flemming left-hand rule gives the direction of …

## Construction of a DC Generator

A DC Generator is an electrical device which converts mechanical energy into electrical energy. It mainly consists of three main parts, i.e. magnetic field system, armature and commutator and brush gear. The other parts of a DC Generator are magnetic frame and yoke, pole core and pole shoes, field or exciting coils, armature core and …

## DC Machine

A DC Machine is an electro-mechanical energy conversion device. There are two types of DC machines; one is the DC generator, and another one is known as DC motor. A DC generator converts mechanical power (ωT) into DC electrical power (EI), whereas, a DC motor converts d.c electrical power into mechanical power. The AC motor …

## Parallel Operation of a Single Phase Transformer

Parallel Operation of a Single Phase Transformer means that the two or more transformers having the same polarities, same turn ratios, same phase sequence and the same voltage ratio are connected in parallel with each other. The circuit diagram of two single-phase transformer A and B connected in parallel are shown below: Let, a1 is …

## Parallel Operation of a Transformer

The Transformer is said to be in Parallel Operation when its primary winding is connected to a common voltage supply, and the secondary winding is connected to a common load. The connection diagram of the parallel operation of a transformer is shown in the figure below. The parallel operation of a transformer has some advantages likes …

## Types of Transformer

There are various types of transformer used in the electrical power system for different purposes, like generation, distribution and transmission and utilization of electrical power. The different types of transformer are Step up and Step down Transformer, Power Transformer, Distribution Transformer, Instrument transformer comprising current and Potential Transformer, Single phase and Three phase transformer, Auto …

## Power Triangle

Power Triangle is the representation of a right angle triangle showing the relation between active power, reactive power and apparent power. When each component of the current that is the active component (Icosϕ) or the reactive component (Isinϕ) is multiplied by the voltage V, a power triangle is obtained shown in the figure below: The …

## Cooling of Transformer and Methods of Cooling

Cooling of Transformer is the process by which heat generated in the transformer is dissipated or treated to the safe value. This is achieved by various cooling methods of transformer available. The major factor for the generation of heat in the transformer is the various losses like hysteresis, eddy current, iron, and copper loss. Among …