What voltage is supplied to the primary winding of a transformer with 4000 turns, if the secondary winding has 100 turns and the load is supplied with a voltage of 20V at a current of 4A. Resistance of the secondary winding 0.5 Ohm.
W1 = 4000 turns – the number of turns in the primary winding of the transformer;
W2 = 100 turns – the number of turns in the secondary winding of the transformer;
U = 20 Volts – voltage supplied to the load;
I = 4 Amperes – current strength;
r = 0.5 Ohm – resistance of the secondary winding of the transformer.
It is required to determine U (Volt) – what voltage is supplied to the primary winding of the transformer.
Find the load resistance:
R = U / I = 20/4 = 5 ohms.
Then the EMF of the secondary winding is equal to:
e = I * (R + r) = 4 * (5 + 0.5) = 4 * 5.5 = 22 Volts.
The transformation ratio is:
n = W1 / W2 = 4000/100 = 40.
Then the voltage on the primary winding will be equal to:
U = e * n = 22 * 40 = 880 Volts.
Answer: the voltage on the primary winding is 880 volts.