Transformer : Equivalent Circuit

Equivalent circuit diagram of a transformer is basically a diagram which can be resolved into an equivalent circuit in which the resistance and leakage reactance of the transformer are imagined to be external to the winding. Where, R1 = Primary Winding Resistance. R2= Secondary winding Resistance.

1. Elementary Theory of an Ideal Transformer

2. E.M.F. Equation of a Transformer

3. Transformer on No-load  

4. as so so Transformer on load ‘

5. Transformer on load ‘          

6. Transformer on load so

7. Transformer with Winding Resistance but No Magnetic Leakage

8. Equivalent Resistance

9. Equivalent Resistance

10. A transformer with magnetic leakage is equivalent to an ideal transformer with inductive coils connected in both primary and secondary circuits Magnetic Leakage

11. Transformer with Resistance and Leakage Reactance leakage reactances can also be transferred from one winding to the other

12. Transformer with Resistance and Leakage Reactance

13. Prob : A 50-k V A, 4,400/220-V transformer has R 1 = 3.45 W , R 2 = 0.00 9 W . The values o f reactance s ar e X 1 = 5.2 W an d X 2 = 0.01 5 W . Calculat e fo r th e transforme r ( i ) equivalen t resis - tanc e a s referre d t o primar y (ii) equivalen t resistanc e a s referre d t o secondar y (iii) equivalen t reac - tanc e a s referre d t o bot h primar y an d secondar y (iv ) equivalen t impedanc e a s referre d t o bot h pri - mar y an d secondar y (v ) tota l C u loss , firs t usin g individua l resistance s o f th e tw o winding s and secondl y , usin g equivalen t resistance s a s referre d t o eac h side.

14. Equivalent Circuit   A: B: Equivalent circuit of A:   ;    

15. Equivalent Circuit Secondary Circuit Equivalent Primary values

16. Equivalent Circuit Exact equivalent Circuit Simplified circuit by transferring the exciting circuit across the terminal

17. Equivalent Circuit Further simplified by omitting  

18. Equivalent Circuit