# DC Machines

## Commutation in DC Machine

The currents induced in the armature conductors of a DC generator are alternating in nature. The change from a generated alternating current to the direct current applied involves the process of Commutation. When the conductors of the armature are under the north pole, the current which is induced flows in one direction. While the current …

## Types of DC Motor

A Direct Current Motor, DC is named according to the connection of the field winding with the armature. Mainly there are two types of DC Motors. One is Separately Excited DC Motor and other is Self-excited DC Motor. The self-excited motors are further classified as Shunt wound or shunt motor, Series wound or series motor …

## Compound Wound Generator

In a Compound Wound Generator, there are two sets of the field winding on each pole. One of them is connected in series having few turns of thick wire, and the other is connected in parallel having many turns of fine wire with the armature windings. In other words, the generator which has both shunt and …

## Types of DC Generator – Separately Excited and Self Excited

The DC generator converts mechanical power into electrical power. The magnetic flux in a DC machine is produced by the field coils carry current. The circulating current in the field windings produces a magnetic flux, and the phenomenon is known as Excitation. DC Generator is classified according to the methods of their field excitation. By …

## Back EMF in DC Motor

When the current-carrying conductor placed in a magnetic field, the torque induces on the conductor, the torque rotates the conductor which cuts the flux of the magnetic field. According to the Electromagnetic Induction Phenomenon “when the conductor cuts the magnetic field, EMF induces in the conductor”. The Fleming right-hand rule determines the direction of the …

## What is a DC Motor

A Motor is a machine that converts electrical energy into mechanical energy. There is no difference between a DC motor and DC generator from a construction point of view. The only difference is that the generators are usually operated in more protected locations and, therefore, their construction is generally of the open type. On the …

## Emf Equation of a DC Generator

As the armature rotates, a voltage is generated in its coils. In the case of a generator, the emf of rotation is called the Generated emf or Armature emf and is denoted as Er = Eg. In the case of a motor, the emf of rotation is known as Back emf or Counter emf and …

## 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 …