The Emf per turn of a single phase 20KVA 2200 / 220 V , 50 Hz transformer is 20V. Max Flux Density 1.5 T. Primary turn of this transformer is

A. 120

B.130

C.140

D.110

Ans: D. 110 

Explanation :

Here is given that E1 = 2200 & E2 = 220V 

Frequency F = 50Hz 

Emf per turn = 20V 

Max flux Density = 1.5 T

Primary turn N1 = ?

Formula for Number of primary turn N1 = E1 / Emf per turn 

                                                                          = 2200 / 20

                                                                          = 110 turns 

So primary winding turns is 110 .

for More Under standing here we found Secondary turn 

Formula for Number of secondary turn N2 = E2 / Emf per Turn 

                                                                               = 220 / 20 

                                                                               = 11

So Secondary winding Turn are 11.

Now we find value flux 

Formula for value flux = Emf per Turn / 4.44 f 

                                          = 20 / 4.44 * 50

                                          = 20 / 222

                                          = 0.090 Weber

Here Maximum value of Flux is 0.090 weber.

Now Find Cross Sectional Area of Core 

Formula for cross sectional area of flux = Maximum value of flux / Maximum flux density 

                                                                        = 0.090 / 1.5 

                                                                        = 0.06 Meter Square 

Here Cross sectional area of core is 0.06.