Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
Q. Find the line current after the addition of capacitor bank? A 60-Hz, three-phase motor draws 25 kVA at 0.707 lagging power factor from a 220-V source. It is desired to impro
describe the circuit and working of a q meter?
Vital parameters of regulator quality: 1. The output voltage's temperature coefficient of is the change in output voltage with temperature (perhaps averaged over a certain tem
What is the desirable properties of an insulation material? Insulation materials have the desirable properties are as follows: 1. Very fine dielectric strength such as of mi
Q. A balanced delta-connected load has a per-phase impedance of 45 60° . It is connected to a three-phase, 208-V, 60-Hz supply by a three- phase feeder that has a per-phase impeda
A 4000-V, 5000-hp, 60-Hz, 12-pole synchronous motor, with a synchronous reactance of 4 per phase (based on cylindrical-rotor theory), is excited to produce unity power factor at
FET operation: Figure: I-V characteristics and output plot of a JFET n-channel transistor. The FET manages the flow of electrons (or electron holes) from the sourc
compensation techniques
Explain the Power Transmission Lines Transmission and distribution of electric power is accomplished by using overhead lines or underground cables. Overhead lines are normally
Load Stack Pointer This instruction loads the stack pointer register with the 16 - bit data specified in the instruction. The 16 - bit data. When stored in sp registe
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
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!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd