đức anh đề cương máy điện

đề cương máy điện 2 bằng tiếng anh cho các kĩ sư clc outline machine 2 dành cho các bạn sinh viên nghành điện do nhóm sv trường đại học điện lực tự mày mò nghiên cứu,đề cương tuyển của đh điện lực dành cho sv khôi clc ôn tập thi kết thúc học phần đề cương chỉ gồm các bài lý thuyết được bọn mình tự làm bằng tiếng anh và có hình ảnh minh họa

1.a) What are the requirements of dc machine's armature windings?

b) Define the winding pitches, collector's segment and pole pitch?

c) Draw a figure of the winding pitches in case of simplex lap winding?

3 : Present the distributon of magnetic field on the armature surface when the brush is on the geometrical neutral axis and the main magnetic field is not

7) What are the reasons and conditions for establishing a replacement circuit of a transformer? Draw the equivalent circuit of transformer and explain the

parameters?

the magnetizing circuit parameter of the transformer

determine the primary and secondary circuit impedance of the transformer?

10: write the basic set of equations of an asynchronous machine in the case of a rotating rotor Draw the vector graph ?

11) write the basic set of equations of an asynchronous machine in the case of a rotating rotor? Draw the vector graph in motor mode and generator mode

12 Establish the equivalent circuit of induction machines in case of stationary rotor ?

13 : Draw the equivalent circuit of induction machines in the case of rotating

on? Which are the properties of amature reaction when working with capacitive load?

15: establish the equivalent voltage equation of syn.machine? in case of

unsaturated magnetic circuit, draw the vector diagram of synchronous generator salient pole? What’s comments from the vector graph?

B) draw curve of this power-angle characteristic?

1.a) What are the requirements of dc machine's armature windings?

b) Define the winding pitches, collector's segment and pole pitch?

c) Draw a figure of the winding pitches in case of simplex lap winding?

a) Requirements for winding:

- generate the necessary electromotive force such as: a passant current which produce the required torque, do not give the overheating

- ensure for a good changement of direction

- have a simple, sure are safe structure

-The mix winding pitch: is the distance between two fist working-edge of two adjacent elements

-The collector pitch yg=: is the distance between to winding-edge of one winding element

Y1= Y=YG=1

Y2=Y1-YG

c)

Uniform winding element

Level winding element

induced part and pole within one pole step

�� is scattered flux:

The magnetic flux linking the loop separately to each winding is called the flux magnetic flux, we have the stator magnetic flux, the only stator loops with the stator winding, the rotor flux magnetic floss loops with the rotor winding only Dissipation flux is characterized by dissipation resistance

3 : Present the distributon of magnetic field on the armature surface when the brush is on the geometrical neutral axis and the main magnetic field is not

considered

conductor per unit length equival

u i

=

is the current in conductor

D is the outer diameter of the armature (cm)

A is the number of branched part

- If the circuit is symetrical with the midpoint of two brushes, according to the law of total current, the magnetomotive force of armature part at a point x is

.2.

ux

F =A x

(A/pair of pole)

rotors, F uxis the magnetic force required to force the path through the two distance δ

is

uwx uwx.2

F =H δ

- The word bromide in the opening will be

in to the armature part by the brush as normal working condition

+ Collector is not consistant with the central axis

+ Rotating part is not well balenced

+ The surface of collector is not flat

+ Force on brush is inappropriate

+ The reactant of electromotive force does not remove completely the reversing electromotive force

+ The current’s distribation on the contact surface is not uniform

5 : Present the method of improving the reversing direction rectification in DC machineby using the auxiliary magnetic pole ?

magnetic field also knows as a reversig magnetic field at neutral zone by

placing auxiliary pole between the main pole

2) The magnetomotive force ( emf ) of auxiliary pole Ft must be :

a) Direction ,inverse with horizonal emf of induced part Fuq

auxiliary field to genenate the reversing emf epk

c) Therefore ,the auxiliary pole in the generator must be set to have do samepolarity as the main pole with the egles of the winding elememt at the auxiliary pole appwatching inverseinthe motor mode.

d) Due to the reactant emf epk=Iu and edc is proportial with Bdc ,so Bdc have

to be ratio with Iu

is changed only is a zone that auxiliary polr circuit is not saturated

pole and induced part gap The width of auxiliary pole =( 0,4 – 0,8 ) time the width of reversing director zone

auxiliary pole = number of main pole

- When the transformers works with load the total magnemotive force

(i1.w1+i2.w2) of the primary and secondary winding generated the main magnetic flux in transformers

- When the transformers works in the opens circuit case: the secondary winding is opened the current in primary winding is i0, the magnemotive force i0.w1

produces the main magnetic flux in transformers

7) What are the reasons and conditions for establishing a replacement circuit of a transformer? Draw the equivalent circuit of transformer and explain the

parameters?

Reason: In order to simplify the transformation of transformer and power system,

we replace the electric circuit and magnetic circuit of transformer to an equivalentcircuit This consist of resistance and reactance called an repalacement circuit of transformer

Condition: In the process of conversion It makes sure that the physical and energyprocess have not to change, such as transmission power, machine losses,etc… The Equivalent Circuit of Transformer:

the magnetizing circuit parameter of the transformer

open circuit experiment

I0 is the open circuit current

X0 is the open circuit reactance

Z0 is the open circuit inpedance

R0 is the open circuit resistance

9.Draw a short - circuited experiment diagram and introduce the pitches to

determine the primary and secondary circuit impedance of the transformer?

- The secondary winding is shorted Determine: Un, In, Pn

- The primary winding is applied Zn=

a low voltage for obtaining I1n= I1dm

-E1=I0 (rm+jxm) =I0 *Zm

Where

U1, E1, I1: voltage,emf and current of stator winding

r1, x1, Z1: resistance, reactance and impedance of satator winding

E’2, I’2:emf and current of rotor winding which area converted to stator windingr’2, x’2: resistance, rectane of rotor which are conveted to stator winding

s: coefficient of slide

rm: resitance of magnetic circuit which is characteristic for iron losses

stator and rotor

I0:current in magnectic circuit which produces the mmf F0

The vector graph

11) write the basic set of equations of an asynchronous machine in the case of a rotating rotor? Draw the vector graph in motor mode and generator mode.

Emf : electromotive force

Mmf :magnetomotive force

U1=-E1+I1(r1+jx1)=- E1+ I1Z1

0=E2'- I2'(r'2+jx2')= E2'- I2'(r'2+jx2'+ r2')

E2'= E1

I1+ I2'= I0

-E1= I0(rm+jxm)= I0 Zm

Where:

U1, E1, I1: voltage, emf and current of stator winding

r1, x1, Z1: resistance, reactance and Impedance of stator winding

E'2, I'2 : emf and current of rotor winding which are converted to stator windingr'2, x2' : resistance, reactance of rotor winding which are converted to stator winding

s : coefficient of slide

rm : resistance of magnetic circuit which is characteristic for iron losses

xm :reactance of magnetic circuit which presents the mutal inductance between stator and rotor

I0 : is current in magnetic circuit which produces the mmf F0

12 Establish the equivalent circuit of induction machines in case of stationary rotor ?

- When rotor is non-rotating : f2 = f1, so the voltage transform rotio :

Eσ1 : is dissipated emf induction in stator

I1r : is drop voltage in stator circuit

Z1=r1 + jx1 : is impedance of stator winding

is:

0 = -E2 + I2 .( r2 + jx2 ) = -E2 + I2Z2

r2 : rotor resistance

x2: dissipated reactance in rotor winding

Z2: impedance of rotor winding

-E1 = I0 Zm = I0 ( rm + j xm )

rm : resistance of magnetic circuit which is characteristic for iron losses

Xm: reactance of magnetic circuit which produce the mmf F1

- Converting the resistance due to losses is :m2I22 r2 = m1I2΄ 2 r2’

K=kike : is converted ratio of resistance, reactance and impedance

Conclusion: the final equation of induction machines in case of stationary rotor

U1 E1 I1 : voltage, emf, current of stator winding

r1 , x1, z1 : resistance, reactance, impedance of stator winding

E΄2 + I΄2 emf and current of rotor winding which are converted to stator windingr΄2, x΄2, Z΄2: resistance, reactance, impedance of rotor winding which are

converted to stator winding

rm: is resistance of magnetic circuit which is characteristic for iron losses

xm: is reactance of magnetic circuit which present the mutual inductance

between stator and rotor

I0: is current in magnetic circuit which produce the mmf Fo

The equivalent circuit

When rotor is non-rotating ( stationary rotor ) and rotor winding is shorted, for limiting the current I1 & I2 in stator winding and rotor winding to nominal value,

decreases → the main flux in machine decrease → the magnetomotive force ( mmf ) F0 very small → ignore

F1 + F2 = F0 ≈ 0 (1) → I1 + I2 (2)

With (1) & (2) we have:

I1 = U1/( Z1 + Z΄2 ) = U1 / Zn

Where: Zn = Z1 + Z΄2 = rn + jxn is short circuit impedance of IM

13 : Draw the equivalent circuit of induction machines in the case of rotating

14: What is an amature reaction of synchronous machine? Which does it depend on? Which are the properties of amature reaction when working with capacitive load?

- When a synchronous generator's rotor is spun, a voltage EA is induced in the generator's stator windings If a load is attached to the terminals ofthe

generator, a current flows But a three-phase stator current flow will produce a magnetic field of its own in the machine This stator magnetic field distorts the original rotor magnetic field, changing the resulting phase vo ltage This effect

is called armature reaction because the armature (stator) current affects the magnetic field which produced it in the first place

reaction depends on the power factor i.e the phase relationship between the terminal voltage and armature current

field flux and thereby increasing the electromagnetic force induced in the armature Therefore, when a synchronous generator is capacitively loaded, It’s terminal voltage will increase

15: establish the equivalent voltage equation of syn.machine? in case of

unsaturated magnetic circuit, draw the vector diagram of synchronous generator salient pole? What’s comments from the vector graph?

With symmetric load, the equation of phase the voltage is as follows

Where U: terminal voltage of generator

ru+jxσu : the resistance & the reactance of the armature winding

E� the emf of armature winding

• In case of unsaturated magnetic circuit: E� = E + Eu (2)

Combining the above two equations (1)&(2), we have:

U = E� +Eu– I(ru+jxσu)

Eu = -jIu U = E – jI(ru+jxσu) - I.ru = E – jIxdb - I.ru

Where: xdb = xu + xσu is the synchronous reactance of salient pole synchronous generator

Vector diagram of synchronous generator salient pole

Left – in case of inductive load

Right - in case of capacitive load

B) draw curve of this power-angle characteristic?

A) Active power –angle characteristic

-the active power-angle characteristic of synchronous machine is expressed by:

P=f (); when E= const, U= constWhere it the angle between to vectors of E and U

Ignoring rư since it is much smaller than Xđb, Xd and X, we obtain

P=m.U.I.cosa)in case of salient synchronous machine

Id= Iq=

With:

So P= m.U.I.cos = m.U.I.cos () = m.U.(Icos.cos

= m.U.(Iq.cos + Id.sin)

b) in case of non-sqliend synchronous machine: P=.sin