## Q Factor / Quality Factor of a Coil

The ratio of the inductance L to the resistance R of a coil remains constant for different winding arrangements in the same volume and shape. It makes sense to define this value as a figure of merit to distinguish different coil structures. The quality factor Q is defined by this ratio of L and R. … Read more

## Ward-Leonard Method of Speed Control

As discussed in the previous post “Speed Control of DC Motor”, speed of DC Motor can be controlled by varying the terminal voltage Vt of the DC Motor. Ward-Leonard Method is the application of this principle where the terminal voltage Vtof DC Motor is varied to control the speed of DC Motor. Ward-Leonard Method of … Read more

## Speed Control of DC Motor by Varying Field Flux

In previous post “Speed Control of DC Motor” we discussed the method of speed control of DC Motor by Armature Circuit Resistance Control Method. In this post we will discuss the method of speed control of DC Motor by varying the Field Flux which is known as Field Weakening Method. By Field Weakening Method of … Read more

## Two Wattmeter Method – Measurement of Three Phase Power

There are three methods which are used for the measurement of three phase power in three phase circuits. The three methods are: Three Wattmeter Method Two Wattmeter Method Single Wattmeter Method In this post, we will discuss the Two Wattmeter Method for power measurement. Two Wattmeter Method: In two wattmeter method, a three phase balanced … Read more

## Speed Control of DC Motor

DC Motor speed control means to have full control on the speed of DC Motor. The variation in speed of DC Motor because of variation in load is not the speed control. Therefore intentional variation in speed of DC Motor is called Speed Control. As we know that for a DC Motor having armature resistance … Read more

## Brushless Excitation System

Brushless Excitation System is a technology for providing the field current to the Synchronous Generator without using Slip Ring and Carbon Brushes. As this method of Excitation i.e. Brushless Excitation System do not use Carbon Brushes, therefore the losses because of contact resistance of carbon brushes is eliminated. Also, in case of initial start up … Read more

## Voltage Build up in DC Shunt Generator

In this post we will discuss how Voltage is Build up in DC Shunt generator at No Load. Consider a DC Shunt Generator at no load as shown in figure below. The switch in the field circuit is supposed open and the armature of DC Shunt Generator is driven at rated speed. Because of presence … Read more

## Why DC Series Motor should not be Started at No Load?

In this post we will discuss about the Speed Current Characteristics of DC Series Motor. After going through this post ask yourself the answer of the question “Why DC Motor should not be Started at No Load?” I am sure that you will be able to answer. In DC Series Motor the field winding remain … Read more

## Three Point DC Motor Starter

Three Point Starter for DC Motor have three point for electrical connection namely Line (L) to which positive / negative terminal of DC Voltage is connected, Field (F) which is connected to the field winding of DC Motor and Armature which is connected to the Armature of DC Motor. As it is having three points for … Read more

## Insulation Resistance Test and Polarization Index

Megger is an electrical device which is used to measure the Insulation Resistance by performing Insulation Resistance Test (IR Test). Basically Megger injects High DC Voltage across the Insulator and ground due to which leakage current flows through the Insulator to the ground. By measuring this Leakage Current, Megger calculates the Insulation Resistance. Suppose the … Read more