# transformer

Discussion in 'General Electronics Chat' started by butobhones, Jul 14, 2005.

1. ### butobhones Thread Starter New Member

Jul 14, 2005
1
0
220v +/- 10% 3A

bridge full wave 5A idc

0 220 50/60 hz
0 12 12
0 26 26
6 0 20

i need to compute that given can anyone help me to compute pls give email me the computation neilgarettadeva@yahoo.com or post here so that i can study what wrong in my computation........ thanks a lot!!!!!!

DESIGN FORMULAS FOR FULL WAVE EI CORE TRANSFORMER

I. computation of DC output voltage across secondary
Es = 2.35 * Edc
2.35 = twice the ratio of the RMS to the average value + 5% regulation

II. DC current (Idc) computation
Is = K * Idc = Is = 0.707 * Idc

non-bridge bridge
full wave 0.707 1.06
half wave 1.40 2.20

III. Output power computation: (Pout)
Pout = Es * Is Pout = Es1 * Is1 + Es2 * Is2 (this is used in multi-tap)

IV. Power input in Volt-ampere (VA) comp.
VA = Pout/ efficiency %

V. Tongue Area (A) comp. in sq. inch
A = sq. root of VA / 5.58 (5.58 is a given factor)

VI. Tongue Area (A), tongue width (tw), stacking height (g) computation:
g = tw = sq. root of A
Note: get the next highest value if sq. root of A is higher than standard

VII. Window width (W), tongue lenght (tl), in relation to tongue width (tw)
W = 0.5 * tw tl = (3/2) * tw

VIII. Primary (Np) & Secondary (Ns) turns comp.
Np = 3.49 * Ep * l^6 / f * B * A Ns = 1.05 * Np * Es / Ep

Note: 3.49 & 1.05 are given factors, f = frequency A = standard tw
B = flux density in gauss

IX. Magnetic wire size comp & Ip comp;
Ip = VA / source line (Eac)

dp = 1.13 * [(sq root of Ip / 2470 - 585) * (log VA)]

ds = 1.13 * [(sq. root of Is / 2470 - 585) * log VA)]

Note: diameter result refer to commercial size & use the next highest size if not of same value

X. Winding lenght (wl) comp;
wl = tl - (2 * 0.125) - (2 * 0.032)

XI. turn / layer (T/L) & # of layers (L#) comp.
T/L = wl / dp (w/insulation)
T/L = wl / ds (w/insulation)

L# p = Np / (T/L)
L#s = Ns / (T/L)

XII. Winding build - up (WB) comp.
WBp = L#p * (dp + 0.002)
WBs = L#s * (ds + 0.002)
WBtotal = 1.1 [(0.095 + WBp + WBs + (2 * 0.002)]

Note: compare WBtotal against Window width (W). it should not exceed 90% of W

XIII. Lenght (L) of magnet wire to be used for computation thru mean lenght of turn (MLT) of each winding
MLTp = 2 (tw + g + 4b) + (pi * WBp)
MLTs = 2 (tw + g + 4b) + [pi * (2WBp + WBs)]
Lp = MLTp * Np Ls = MLTs * Ns

XIV. Wire weight (Ww) comp.
Wwp = (Lp / 12) * (f/1000)
Wws = (Ls / 12) * (f / 1000)

Note: f = weight in pounds / 1000 ft.
all weight results should be rounded off to the next highest weight in terms of 1/8, 1/4, 1/2, 3/4, 1, 1 1/8 etc.

XV. computation of coild resistance (Rl), copper losses (Lcu), Core loss (Lc), voltage drop (Vdp)
Rlp = (Lp/12) * (R / 1000)
Rls = (Ls / 12) * (R / 1000)

Note: R is resistance / 1000 ft.

Lcup = Ip squared * Rclp Lcus = Is squared * Rcls

Core loss (Lc) = (Approximate core loss) * (Core weight) / lb.
Lc = (w/lb) * (lb.) / lb.

Voltage drop prim. (Vdp) = Ip * Rclp Vds = Is * Rcls

XVI. Efficiency (n) & voltage regulation (Vr) comp.

n = Pout / Pout + Lc + Lcu

Vr = (Is * Rls) + [(Ns + Np)squared] * Rlp / Es

thanks again....................................................................

2. ### n9xv Senior Member

Jan 18, 2005
329
1
UUUHHH!

What was the question?

3. ### mozikluv AAC Fanatic!

Jan 22, 2004
1,437
1
hi

the formulas you have qouted are from my post at the transformer subforum. you can still use those for a center tap transformer.

your 12v-0v-12v is just like building a 0v-24v transfo. except you are placing the ground point at the center of the winding. in a 24v the start of your winding is you ground point and the end of your winding is your 24v output. if you put a center tap, your start and end will become your 12v and your center tap is your ground point.