Demagnetizing and cross magnetizing effects , Electrical Engineering

Assignment Help:

Q. What do you understand by demagnetizing and cross magnetizing effects of armature reaction in a d.c. machine. Derive the expression for calculation of demagnetizing and cross magnetizing ampere - turns when brushes are given a shift from geometrical neutral axis.

Sol.  Let the brushes be given a forward shift in a generator or backward shift in a motor, so that brushes axis is now along the magnetic neutral axis (MNA). In other words, the brushes are given a shift through an angle θ and occupy a position BQ. The armature flux Φa = OB must be along the brush axis. Flux Φa can now be decomposed into two components; OC and OD. The component OC = Φa sinθ is opposing the main field Φf. Therefore, Oc has a demagnetic effect on the main field flux. The other component Od, being perpendicular to the main flux Φf, is the cross magnetizing armature flux. Note that the resultant flux ΦR is obtained from the phasor sum of Φf and Φa, i.e. ΦR = Φf + Φa. It is observed that the brush shift, the resultant flux gets reduced from its no - load value even if there is no magnetic saturation.

 

Draw RS making an angle θ with respect to GNA and on the other side of brush shift. The total ampere turns can now be divided into two groups. The conductors shown in angle ROP and QOS or the conductors lying in angle 4θ for every 360o electrical (or 2θ for every 180o electrical) are producing a flux opposite to the main field - flux. This can be verified by the right - hand grip rule. Hence the ampere turns due to the conductors contained in 4θ degrees for every 360o electrical are demagnetizing in nature.

 

 

 


Related Discussions:- Demagnetizing and cross magnetizing effects

Electronics, Let me know if you can help during the test

Let me know if you can help during the test

Adc instruction, ADC   Instruction This instruction is used to add th...

ADC   Instruction This instruction is used to add the contents of any register of any register  memory location and carry  flag with the  contents of accumulator  and result  i

Theoretical circuit, Theoretical Circuit The theoretical circuit is ava...

Theoretical Circuit The theoretical circuit is available in form 1.Passive materials with mediocre dimension is used by the manufacturer. In order to make a theoretical circuit

What do you mean by signal processing, Q. What do you mean by Signal Proces...

Q. What do you mean by Signal Processing? The essential feature of communication, control, computation, and instrumentation systems is the processing of information. Because of

Explain in brief the functions of clock generator chip, Explain in brief th...

Explain in brief the functions of the clock generator chip, 8284. 8284 Clock generator: The 8284 is an ancillary element to the microprocessors. Without any clock generato

Pop instruction, POP Instruction This instruction  copies the contents ...

POP Instruction This instruction  copies the contents  of the top  two locations  of the  stack into the  specified  register pair. The  contents  of stack pointer register are

Decimal to binary conversion, Decimal  to binary Conversion To conver...

Decimal  to binary Conversion To convert a decimal  number to binary  any one  of the followings  two methods  can be used. Methods1 : This  is very common  methods of co

Potentiometers , Which potentiometer do I need to control; 6v 2amps dc?

Which potentiometer do I need to control; 6v 2amps dc?

Unijunction transistor, UniJunction Transistor: (abbreviated as UJT)...

UniJunction Transistor: (abbreviated as UJT), also called the double base diode, is a 2 layer, 3 terminal solid state switching device. The device has a unique characteristi

Alioni Alex

6/25/2013 3:43:32 PM

your service is clearly the definition of education for this little boy you should be happy see how your service is useful to world and you I apreciate .Thanks; to be continued

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