Answer to Question #239636 in Electricity and Magnetism for Arvin Shopon

Question

The primary winding of the welding transformer has 1000 turns and the secondary winding 110 turns. It is connected to the mains at a voltage of 230 V, giving a secondary current of 120 A. Assume an ideal welding transformer.

a) What is the primary current? How big a fuse should there be behind the socket to which the welding transformer is connected - which of the 10 A, 16 A or 20 A fuses is large enough?

b) What is the secondary voltage?

c) Why is the secondary current in the welding transformer desired high?

Answer 1

Gives

$N_1=1000\\N_2=110\\V_1=230V$

$I_2=120A$

Part(b)

$\frac{V_1}{V_2}=\frac{N_1}{N_2}\\V_2=\frac{N_2}{N_1}\times V_1$

$V_2=\frac{110}{1000}\times 230$

V₂=25.3V

Part(A)

$I_1=\frac{N_2}{N_1}\times I_2$

$I_1=\frac{110}{1000}\times 120=13.2A$

Part(c)

big a fuse should there be behind the socket to which the welding transformer is connected 10 Amp

$I_2=120A$ then turn $N_2=110$

High current flow in low turn transformer

$I\alpha \frac{1}{N}$

Current inversely proportional to turns