TRANSFORMERS

Question 1

generated emf of tranformer

Answer 1

Ep = 4.44f O Np
Es = 4.44f O Ns

Question 2

voltage, current, turns,frequency,apparent power relationship on a transformer

Answer 2

primary/secondary =primary/secondary except current which is secondary/primary

Question 3

weber to maxwell (lines of force) conversion

Answer 3

1 Wb = 1x10 ^ 8

Question 4

tesla to weber/m^2

Answer 4

1 T = 1 wb/m^2

Question 5

equivalent resistance referred to primary

Answer 5

Rep = Rp + [(a^2) (Rs)]

Question 6

equivalent reactance referred to primary

Answer 6

Xep = Xp + [(a^2) (Xs)]

Question 7

equivalent impedance

Answer 7

a^2 = Zp/Zs

Question 8

equivalent resistance referred to secondary

Answer 8

Res = [Rp / (a^2)] + Rs

Question 9

equivalent reactance referred to secondary

Answer 9

Xes = [Xp / (a^2)] + Xs

Question 10

effective resistance short circuit test

Answer 10

Re = Pcu/ Isc^2

Question 11

effective impedance short circuit test

Answer 11

Ze = Esc / Isc

Question 12

effective reactance short circuit test

Answer 12

Xe = sqrt (Ze^2 - Re^2 )

Question 13

hysteresis loss

Answer 13

Ph = Kf x f x B^1.6 x V

Question 14

eddy current loss

Answer 14

Pe = B x E^2

Question 15

transformer efficiency

Answer 15

po / po+pcu+pfe

Question 16

copper loss at fractional load

Answer 16

pcu fractional= X^2 (Pcu full load)

Question 17

step up autotransfomer current at common winding 2 formulas

Question 18

step down autotransfomer current at common winding 2 formulas

Question 19

loading of parallel transformers