Electromagnetic torque , Electrical Engineering

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

 

 

Posted Date: 8/23/2012 12:40:40 AM | Location : United States







Related Discussions:- Electromagnetic torque , Assignment Help, Ask Question on Electromagnetic torque , Get Answer, Expert's Help, Electromagnetic torque Discussions

Write discussion on Electromagnetic torque
Your posts are moderated
Related Questions
under three phase 4 wire load unbalanced distribution network how to calacualte the voltage across the load when no load resistance is specified, however the real and reactive powe

how many points are required to make an parabola in offset method when vertical point has 4 points


V- I Characteristics The operation of the  diac can be explained by imagining it as two diodes connected  in series. When  applied voltage in either polarity is small ( less t


Sign flag Since D 7  bit in the  results is 0sign flag is reset. This also  shown that the results is positive.

Ask question #Minimukkgkmm 100 words accepted#

Algorithm  pseudo code and flow  charts Algorithm:   before  writing  the program  the programmer must understand  the problem  for which are  program is to  be written. Then

Seal Management - Meter Field Testing For an effective seal management system it is necessary that: i) The  seals  used  are  tamper  proof,  that is they  cannot  be  remo

Q. What do you mean by sub address? A sub address, though a part of the ISDN address, isn't considered as an integral part of the numbering scheme. Sub address is carried in a