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Graph theory has many applications in several fields such as engineering, physical, social and biological sciences, linguistics etc. Any physical situation that involves discrete objects with interrelationships can be represented by a graph. In Electrical Engineering Graph Theory is used to predict the behavior of the network in analysis. However, for smaller networks node or […]

The dc generators and dc motors have the same general construction. In fact, when the machine is being assembled, the workmen usually do not know whether it is a dc generator or motor. Any dc generator can be run as a dc motor and vice-versa. All dc machines have five principal components viz (I) field

A system is single or polyphase depending upon whether the sources feeding it are single or polyphase. A source is single or polyphase according to whether there are one or several driving voltages associated with it. For example, a three-phase source is a source containing three alternating driving voltages that are assumed to reach a

In the event of failure or non-availability of the primary protection some other means of ensuring that the fault is isolated must be provided. These secondary systems are referred to as ‘back-up protection’. Back-up protection may be considered as either being ‘local’ or ‘remote’. Local back-up protection is achieved by protection which detects an un-cleared

WHAT IS POWER FACTOR Power factor (PF) is simply the relationship between the active and reactive power on an electricity distribution network and a measure of whether the system’s voltage and current are ‘in phase’. Take, for example, a frothy latte. The coffee body is the ‘active power’ that you can use to do work.

The stator winding of a synchronous motor is similar to that of a 3 phase induction motor. The rotor consists of salient poles excited by dc field windings like that of inward-projecting poles of a dc motor. The rotor field windings are energized by direct current passed through slip rings from an external source or

Single phase motors are manufactured in fractional kilowatt range to be operated on single phase supply and for use in numerous applications like ceiling fans, refrigerators, food mixers, hair driers, portable drills, vacuum cleaners, washing machines, sewing machines, electric shavers, office machinery etc. Single phase motors are manufactured in different types to meet the requirements

The direction of rotation of a universal motor can be changed by either: (i) Reversing the field connection with respect to those of armature; or (ii) By using two field windings wound on the core in opposite directions so that the one connected in series with armature gives clockwise rotation, while the other in series with the

The stator of a standard split phase motor has two windings viz., a main winding and an auxiliary winding. These two windings have different ratios of resistance to inductive reactance. The windings are connected in parallel across the single phase ac supply. The line current is thus split into two parts; one part flowing through

Capacitor type split phase motors are generally similar to the standard split phase construction except for the addition of capacitor and a slightly modified switching arrangement for the two value capacitor type motors. The three types of capacitor split phase motors have been shown in Figure. Figure: Three types of capacitor type split phase motors