1. Government Engineering college, valsad .
Subject :- Elements of
Electrical
Design.

2. DESIGN PROCESS OF CHOKE

3. Submitted to:- prof-J.B patel
Submitted by:-
Jinish biju ( )
Nakum Nayan ( )
Patel Hardi ( )
Tandel Vandana ( )

4. Steps for designing choke
Design of choke is similar to design of small Transformers. In chokes the volume of copper required is half that of a corresponding transformer.Therefor a choke may be thought of a transformer having a rating of Q/2,Where Q=volt ampere rating .
Specifications:
(i) Rated voltage, V
(ii) Current carrying capacity, I in Amp.
(iii) Supply frequency f.

5. Step-1 Calculation of required core size Apparent power Q=VI
The choke may be thought of a transformer having rating of Q/2. Therefore , The value of turns per volt Te is selected corresponding to volt-ampere rating of Q/2 from the table of turns per volt.

6. ᶲm = 1/ 4.44 f Te Net area of core, AC= ᶲm/ Bm
Maximum flux in the core
ᶲm = 1/ 4.44 f Te
Net area of core,
AC= ᶲm/ Bm
Assume, maximum flux density Bm =1 Wb/m².
Gross area of core,
Agc =Ac/Ks
Where, Ks=stacking factor
=0.9

7. If we assume square cross section for the core then
Depth of core=Width of limb
Gross core area , Agc=A*A
So, Width of central limb, A=√Agc

8. Step=2 Design of winding Number of turns,N=V*Te
Area of conductor or wire a=I/δ
Where, δ=current density and its value is assumed between
2.2 to 2.5 A/mm².
Enamlled round conductor are used for the winding of choke.
a=π/4 (d²)
Diameter of conductor or bare wire
D=√4/π(a)

9. Step=3 Calculate the window area required
Window area required for the winding=Na/ Sf
Where, Sf =space factor =0.8(d/d1)²
Where, d=diameter of bare wire
Where,d1=diameter of insulated wire
In order to accommodate insulation between layers and
former in the window, actual window area required is about 20% more.
So , Total Window area required=1.2 Na/Sf

10. Step 4
EI,TU,JJ type lamination are used for the chokes. The dimention of EI and TU stamping are given in table E-I type stamping andT-U type stamping respectivly.
For a tube-light choks,J-J lamination are usually used.The dimension are use as shown in fig

11. 40 52 12 36 12 12 52 40 J-J stamping (All dimension are in mm)

12. Step 5 Impedance of choke coil ,
Z=voltage applied/current throuth the coil
=V/I
=N/TeI
Total MMF required for the choke coil
=MMF required for the iron part+MMF required
for air gap
Usually the MMF required for the iron part is very small as compared to the Mme required for iron part.
Neglecting MMF required for iron part.

13. total AT=MME rquired for air gap =ngatglg
Therefor ,
total AT=MME rquired for air gap
=ngatglg
where atg = Bm/√2
lg=length of each air gap
ng=number of air gaps in series in the flux path
Therefor,
I=Nagtglg/N
Substituting the value of current I in equation ,we get

14. Z=N/TI Z=N²/(Ngatglg) For EI,TU and JJ type lamination ,there are two air gap in series in the magnetic flux path

15. Thank you