ٽرانسفارمر ٺاهڻ لا فارمولا جو استعمال۽ ضرورت

[Sindhi Media]

ٽرانسفارمر ٺاهڻ لا فارمولا جو استعمال۽ ضرورت

There are two approaches used in designing transformers. One uses the long formulas, and the other uses the Wa product. The Wa product is simply the cores window area multiplied by the cores area. Some say it simplifies the design, especially in C-core (cut core) construction. Most manufacturers of C-cores have the Wa product added into the tables used in their selection. The designer takes the area used by a coil and finds a C-core with a similar window area. The Wa product is then divided by the window area to find the area of the core. Either way will bring the same result.

 

[Sindhi Media]

توهان ڏٺو ته ٽرانسفارمر ڊزائين لا ٻه اپروچون استعمال ڪيون وانديون آهن۔ هڪ اپروچ (فارمولا جي مدد سان) ته ٻي (وا پروڊڪٽ) جي وسيلي۔ وا پروڊڪٽ محض هڪ ڪور جي ونڊيوايري آهي جنهنکي ڪور ايري سان ضرب ڪري حاصل ڪيو ويندو اهي۔ اسپيشلي (سي ڪور) يعني (ڪٽ ڪور ) ۾ ڪن چواڻي ته اهو ڊزائين کي آسان ٺاهي ٿو۔ اڪثر (ڪٽ ڪور يا سي ڪور) جا مينيوفيڪچرر (وا پروڊڪٽس کي تيبل ۾ رکي پيش ڪن ٿا ۽ پو ٽيبل مان ان سليڪشن کي حاصل ڪن ٿا۔ ڊزئينر ڇا ڪندا آهن جو ڪوائل جيڪو ڪور استعمال ڪندو آهي ان جي ايريا وٺي ۽ ان جي سي يا ڪٽ ڪور معلوم ڪن ٿا ساڳئي ونڊو ايريا مطابق۔ پو وا پروڊڪٽ کي ونڊو ايريان سان ونڊ ڪري ڪور جي ايريا معلوم ڪبي آهي۔ رزلٽ ٻنهين طريقن سان ساڳي حاصل ٿيندي آهي۔
For a transformer designed for use with a sine wave, the universal voltage formula is:]
هڪ ٽرانسفارمر جي ڊزائن سائن ويو جي يونيورسل وولٽيج لاِ هي فارمولو هوندو آهي۔

اهڙي طرح

جتي,

E is the sinusoidal rms or root mean square voltage of the winding,

• f is the frequency in hertz,
• N is the number of turns of wire on the winding,
• a is the cross-sectional area of the core in square centimeters or inches,
• B is the peak magnetic flux density in Teslas or Webers per square meter (MKS meas. sys.), gausses per square centimeter, or lines (maxwells) per square inch (cgs meas. sys.).
• P is the power in volt amperes or watts,
• W is the window area in square centimeters or inches and,
• J is the current density.
• Note: 10 kilogauss = 1 Tesla.

This gives way to the following other transformer equations for cores in square centimeters (cgs meas. sys.):

The derivation of the above formula is actually quite simple. The maximum induced voltage,

, is the result of N times the time-varying flux:

If using RMS voltage values and E equal the rms value of voltage then:

and

Since the flux is created by a sinusoidal voltage, it too varies sinusoidally:

where

= area of the core

Taking the derivative we have:

Substituting into the above equation and using

and the fact that we are only concerned with the maximum value yields

 

[Sindhi Media]

آسان فارمولو
Simpler formulae]
A shorter formula for the core area (a) and the turns per volt (T) can be derived from the long voltage formula by multiplying, rearranging, and dividing out. This is used if one wants to design a transformer using a sine wave, at a fixed flux density, and frequency. Below is the short formulas for core areas in square inches having a flux density of 12 kilogauss at 60 Hz (see note 2):

And for 12 kilogauss at 50 Hz:

 

[Sindhi Media]

Equation notes

• Note 1: The factor of 4.44 is derived from the first part of the voltage formula. It is from 4 multiplied by the form factor (F) which is 1.11, thus 4 multiplied by 1.11 = 4.44. The number 1.11 is derived from dividing the rms value of a sine wave by its average value, where F = rms / average = 1.11.

• Note 2: A value of 12 kilogauss per square inch (77,400 lines per sq. in.) is used for the short formulas above as it will work with most steel types used (M-2 to M-27), including unknown steel from scrap transformer laminations in TV sets, radios, and power supplies. The very lowest classes of steel (M-50) would probably not work as it should be run at or around 10 kilogauss or under.

• Note 3: All formulas shown are for sine wave operation only. Square wave operation does not use the form factor (F) of 1.11. For using square waves, substitute 4 for 4.44, and 25.8 for 28.638.

• Note 4: None of the above equations show the stacking factor (Sf). Each core or lamination will have its own stacking factor. It is selected by the size of the core or lamination, and the material it is made from. At design time, this is simply added to the string to be multiplied. Example; E = 4.44 f N a B Sf