Electromagnetic torque , Electrical Engineering

Assignment Help:

Electromagnetic torque 

The torque is given by the force on the armature winding multiplied by its radius. Force on a conductor in magnetic field B is: 

F=B.I.L

so, T=B.I.L.R

The torque opposes the mechanical rotation of the rotor and so the mechanical torque turning the generator must do work against the electromagnetic torque in order to generate the voltage (and current) supplied to the electrical load connected to the generator. Therefore energy conversion occurs from mechanical energy to electrical energy.The flux density B webers/m  can be expressed in terms of the flux per pole, φ,  to give a relation between the electromagnetic torque to be overcome and current produced.

T=Cm.Ø.Ia

C=machine constant

The equivalent circuit representation of an electrical generator is:

 

 

478_Electromagnetic torque.png

 

The generator itself provides the source tosupply the field current I . Residualmagnetism will provide a small generatedcurrent at first that then builds up as thefield current grows, producing moregenerated current, etc. [NB leaving analternator open circuit will cause thevoltage to build up to the point wherediodes used to rectify the output voltagecan be damaged. Never operate an alternator without an electrical load connected. The output voltage is slightly less than the generated voltage due to the volt drop across the armature winding resistance when current flows. The arrangement of connecting the field winding in parallel with the armature is known as a shunt connected machine. The alternative is to connect the field winding in series with the armature, in which case it as known as a series connected machine.

Reversibility principle of electric machines

An electric machine can be operated as a generator or motor depending on the operation conditions. This is known as the reversibility principle of electric machines. For example, if the generator above is supplied from an electrical source, it will operate as a motor

 

 


Related Discussions:- Electromagnetic torque

Avalanche breakdown region, Avalanche breakdown region: Even though th...

Avalanche breakdown region: Even though these regions are well described for sufficiently large applied voltage, they overlap somewhat for small (less than a few hundred milli

Features of tariff policy, Features of tariff policy: For projects who...

Features of tariff policy: For projects whose tariff is determined by performance- based cost of service regulation, the advantages of decreased tariff after full depreciation

Show transformer equivalent circuits, Q. Show Transformer equivalent circui...

Q. Show Transformer equivalent circuits? Transformers come in various sizes, from very small, weighing only a few ounces, to very large, weighing hundreds of tons. The ratings

Prepare the equation for drift velocity and mobility, Question 1: (a) O...

Question 1: (a) Outline the architecture of MIT's iLabs. Design a diagram supporting your explanation. (b) Give advantages/disadvantages of the MIT Microelectronics iLabs wi

What can explain failure of relative ppp to hold in reality, Q. What ...

Q. What can explain the failure of relative PPP to hold in reality? Answer: Government procedures of the price level differ from country to country. One cause for thes

Decision making, Decision  Making The rhombus diamond symbol  is used...

Decision  Making The rhombus diamond symbol  is used to represent  the decision making  process  as shown  below.                                          Figure  De

How can we prove that radio waves are sine waves, What makes them sine? ...

What makes them sine? Ans) Fourier tells that only a sine wave has no harmonic content. The math works out that if you have any wave shape other than a sign wave, you can brea

Eletronic circuits, compensation techniques and biasing arrangements of q-p...

compensation techniques and biasing arrangements of q-point

Zero-bias equilibrium, Zero-Bias Equilibrium In a p-n junction, with n...

Zero-Bias Equilibrium In a p-n junction, with no an external applied voltage, an equilibrium condition is arrived at in which a potential variation is formed across the juncti

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd