Data
Voltage Rating= 230 V/ 24 V
Frequency, f= 50 Hz
Power Rating= 100 VA
Assumptions
Flux density in the core, B = 1 wb/m2
Stacking factor for Core lamination = 0.9
Current Density in the winding, J= 2.3 A/mm2
Turns per Volt, Te = 4.6
Efficiency of the Transformer= 0.95
Core Design
Flux in the core, Øm =1/ (4.44 f Te) =1/ (4.44*50*4.6) =
9.7924 * 10-4 Wb
Net Core Area, Ai= Øm/Bm= 9.7924 * 10-4 /1=
9.7924 * 10-4 m2
Gross Core Area, AG = Ai/ Stacking factor = 10.8804
cm2
A= √AG = 3.2986 cm
A= 3.2986 cm ≈ 3.3 cm
D= A/2 = 1.6493 cm ≈ 1.65 cm
E=D ≈ 1.65 cm
C= 3A= 9.8958 ≈ 9.9 cm
F> E or D
F ≈ 1.8 cm
B= 2D+A+2F= 10.2 ≈ 10.2 cm
Window Area = ((B-2D-A)/2)*(C-2E) ≈ 11.88 cm2
Winding Design
Primary Current, Ip = VA/ (Eff.* Vp) = (100/0.95*230) =0.4577 A
Ap’=0.4577/2.3 = 0.199 mm2
dp’= √((4*0.199)/ᴨ) = 0.5035mm
Nearest Standard Wire Size, dp= 0.508 mm (25 SWG or 24 AWG)
Ap= (ᴨ*dp2)/4= 0.2026 mm2
Turns in Primary, Tp= Te* Vp= 4.6* 230= 1058 Turns
Turns in Secondary, Ts= Te* Vs= 4.6* 24= 110.4 = 111 Turns
5 % more turns for Secondary
Ts= 1.05 Vs* Te= 115.92= 116 Turns
Secondary Current, Is = VA/ Vs= 100/24 =4.1667 A
As’=4.1667/2.3 = 1.8116 mm2
ds’= √((4*1.8116)/ᴨ) = 1.5191 mm
Nearest Standard Wire Size, ds= 1.626 mm (16 SWG or 14 AWG)
As= (ᴨ*ds2)/4= 2.0754 mm2
Space required for Primary winding= (Tp*Ap)/Space factor
Space required for Secondary winding= (Ts*As)/Space factor
Total space= (Tp*Ap)/Space factor + (Ts*As)/Space factor
= (1058*0.2026)/0.8 + (116*2.0754)/0.8
= 568.8715 mm2
25 % additional space for insulation = 1.25*568.8715= 711.0894 mm2
= 7.111 cm2
No. of Stamping
= A/ Thickness of Stamping = (3.33 cm/
0.33 mm)
= 100.9090 = 101
Width of window on Core, W= Window area/ Length of winding
= 6.9488/ (C-2E) = 1.0774 cm
W/2= 0.5264 cm
Weight of Cu wire required = Mean length of turn * (Ap*Tp +As*Ts)*
Density of Cu
Mean length of turn, Tav = 4 (A+ (W/2) + (W/2))
= 17.5312 cm
Wcu = 175.312*(1058*0.2026+ 116*2.0754)* 0.0089
= 710.0776 gm= 750
gm
