star delta transformation

eci subject

1. MICRO-PROJECT SUB:- ELECTRICAL CIRCUIT SUB TOPIC :- STAR DELTA TRANSFORMATION

2. Puranmal lahoti govt. polytechnic collage With the guidance of : proof. Shete D. mam Resource which is used in microproject : electrical circuit book Team discussion Use of internet Notes of provided by teacher. Roll no. Enrollment no. Student name:- 59. 2000160264 Tatphale gurunath maroti 56. 2000160266 Todkari ritesh ajaykumar 63. 2000160268 Waghmare shubham dilip

3. STAR – DELTA TRANFORMATION .

4. LEARNING OUT-COMES After completing this project unit. You will be able to understand followings:- 1. how to convert star –Delta transformation . 2.We known about the star and delta networks.

5. Introduction:- In electrical systems, we have to deal with resistances a lot, arranged in different patterns i.e. parallel, series, mesh etc . Simple single-phase resistive circuits, where resistances are present in parallel or series combination, can be solved by using series or parallel formulas of resistances, there are also few other techniques i.e. Kirchhoff's Laws, nodal analysis etc. to solve such circuits . But in the case of complex 3-phase resistive circuits, we can’t use these basic formulas & thus need better techniques. Star to delta transformation method is one of them.

6. The star to delta transformation can also be expressed as  Y-Δ transformation , it is a mathematical method used to solve complex resistive circuits in 3-phase electrical systems . Its name wye-delta is given to it because of its design. As shown in the figure, Star(wye) looks like Y, while Delta looks like  Δ .  This transformation technique from one form to another was given by  Edwin Kennelly in 1899 , who was an electrical engineer who belongs to the USA. Besides using in electrical circuitries star-delta transformation can also be used in math's to solve different planer graphs. In today’s post, we will have a look at its working, formula, equation, and uses. So, let’s get started with  what is star-delta transformation?

7. Any network can be reduced can be (converted) into two special type of network is known as star and delta networks.. Why star delta transformation ? We use Star-Delta transformation to simplify complex 3-phase circuits. These simplified versions are a lot easier to solve as compared to the original complex ones. So, such transformations actually save us from complex calculations, thus reduce errors & save time. Now let’s have a look at Star & Delta arrangements, one by one:

8. Star Network.

9. Above figure shows the T-Shaped Normal circuit and its equivalent Y-Shaped Connection: If all resistances are connected to a common point(also called Joint) from one end, while the other end(of the resistances) is open, this connection styling is termed as  Star Network or Y Connection (also called wye circuitry). Star Connection is also referred to as  open-loop  as there’s no loop in it. We haven’t performed any transformation in the above figure, instead, we have just draw a single circuit in two different styles, one is called  T-shaped , while the second one is  Y-shaped . In both of these forms, resistances are connected at a single common point called Junction/Joint, represented by J in the above figure. Now let’s have a look at How Delta Network looks like?

10. D elta Network.

11. Above figure shows the normal loop circuit and its equivalent Delta Circuit : If the resistances are creating a loop i.e. each end of resistance is connected to other resistance, such circuitry is termed as  Delta Circuitry ,  Delta Network  or  Delta Connection , denoted by  ∆ . Delta Connection is also referred to as a  closed-loop  as it involves a loop. Again we are not performing any transformation, instead, we are just displaying a single circuit in its two equivalent shapes. In both formats, resistances have created a loop and are connected to one another.

12. Star –delta transformation now , you must have understood the difference between Star & Delta Connection and if you are presented with a circuit, you can easily find whether its a Star or a Delta. Now let’s have a look at How to transform from one shape to another(i.e. Star to Delta & Delta to Star).

13. Transforming a circuit from Star Connection to Delta Connection is called  Star to Delta Transformation . As shown in the below figure, both connections have the same number of resistances but their values are different. So, if we want to convert a Star Connection into a Delta one, then we need to find the values of all Delta resistances i.e. R A , R B  & R C .

14. So, let’s have a look at How to drive equations for Star Delta Transformation.

15. Equation of Star Delta Transformation As shown in the above figure, we need to find the values of Delta resistances. In order to do so, let’s find out the resistance between nodes. Between N1 & N2 : In star connection, the resistance between N1 & N2 is equal to R 1  + R 2 . In Delta connection, resistance R A  is in parallel with R B  & R C , so the resistance between N1 and N2 will be equal to R A (R B  + R C )/(R A  + R B  + R C ).  (using resistance parallel formula) As both circuits are equivalent, so the resistance between similar nodes must be equal and will give us equation A, shown below:

16. Between N2 & N3 : The resistance between nodes N2 & N3 will give us equation B : Between N3 & N1: The resistance between nodes N3 & N1 will give us equation C:

17. Now let’s add Equations A, B & C and we will get equation D, as shown in the below figure : Now let’s subtract equations A, B & C from equation D and we will get values of R 1 , R 2  & R 3 , as shown in the below figure:

18. Now by using these values of R 1 , R 2  & R 3 , we can get the value of R A , R B  & R C , as shown in the below figure:

19. So, using these six equations, we can easily convert Star to Delta and Delta to Star

20. Example of Star Delta Transformation The star-∆ alteration complications are the finest samples to comprehend the idea of the circuitries. The resistance in a star system is represented with (X, Y, Z), which can be seen in the above diagram and the values of these resistances are (X= 80Ω), (Y= 120Ω), and (Z = 40Ω ).] A= (XY/Z) +Y+X) X = 80 Ω, Y= 120 Ω, and Z = 40 Ω By putting these parameters in the above formula we calculate the value of A. A = (80 X 120/40) + 120 + 80 )= (240 + 120 + 80 )= (440 Ω) As we have find value of resistance (B) which is ((ZX/Y) + X+Z). Now we put values in this equation to find the value of B.

21. B = ((40X80/120) + 80 + 40) = (27 + 120) = (147 Ω). Now we can calculate the value of resistance C by this equation C = ((YZ/X) +Z+Y) Putting value in this equation we get C.  ((120 x 40/80) + 40 + 120) = (60 + 160) = (220 Ω)