# Electrical Terms

## 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 …

## 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 …

## Two Wattmeter Method – Balanced Load Condition

The Two Wattmeter Method is explained, taking an example of a balanced load. In this, we have to prove that the power measured by the two wattmeter i.e. the sum of the two wattmeter readings is equal to root 3 times of the phase voltage and line voltage (√3VLIL Cosϕ) which is the actual power …

## Two Wattmeter Method of Power Measurement

Two Wattmeter Method can be employed to measure the power in a 3 phase, three-wire star or delta connected the balanced or unbalanced load. In two wattmeter method, the current coils of the wattmeter are connected with any two lines, say R and Y and the potential coil of each wattmeter is joined on the …

## Measurement of Three Phase Power: Three Wattmeter Method

Power measurement in an AC circuit is measured with the help of a Wattmeter. A wattmeter is an instrument which consists of two coils called Current coil and Potential coil. The current coil having low resistance is connected in series with the load so that it carries the load current. The potential coil having the …

## Star to Delta and Delta to Star Conversion

The conversion or transformation or replacement of the star connected load network to a Delta connected network and similarly, a delta connected network to a star network is done by Star to Delta or Delta to Star Conversion. Contents: Star to Delta Conversion Delta to Star Conversion Star to Delta Conversion In star to delta …