The current ratio in a transformer´s windings depends on the number of turns used in the windings according the next formula:
Formula 1
I1 / I2 = n2 / n1
Where:
I1 is the current flowing through the primary winding in amperes (A)
I2 is the current flowing through the secondary winding in amperes (A)
n1 is the number of turns of primary winding
n2 is the number of turns of secondary winding
Application Example:
Consider a transformer with a 100-turn primary and a 200-turn secondary. When a 100mA load is powered from the secondary, calculate the current flowing through the primary.
Data:
n1 = 100 turns
n2 = 200 turns
I2 = 100 mA
I1 = ?
Applying formula 1:
100/I1 = 200/100
I1 x 200 = 100 x 100
I1 = (100 x 100)/200
I1 = 10000/200
I1 = 50 mA
