Question

The primary of a transformer has 400 turns while the secondary has 2000 turns. If the power output from the secondary at 1000 V is 12 kW, what is the primary voltage?(a) 200 V(b) 300 V(c) 400 V(d) 500 V

Answer 1

Formula : N1/N2 =V1/V2 (Turns Ratio)

Where N is the number of turns in the coil and V is the voltage across the coil. Subscript 1 denotes primary side and subscript 2 denotes secondary side.

Therefore N2=N1*(V2/V1)

N2=1000*(400/250)

N2= 1600 turns.

1600 turns are required in the secondary coil to induce a voltage of 400V in the secondary side when the primary side voltage is 250V.

This is known as a step up transformer.

Answer 2

Answer:

Explanation:

Turns of the primary transformer = 400

Turns of the secondary transformer = 2000

The relation between voltage drop of a coil and number in terms is given as - N1/N2 =V1/V2

Where N is the number of turns in the coil = 400 and

V is the voltage across the coil = 2000.

Therefore,

1000/V2 = 2000/400

V = 200

Efficiency of transformer = 90%

Thus = Output power/input power = 0.9

= ( 200×I) × 0.9 = 12,000

= 12000/ 180

= 67 approx.

Thus, the primary voltage of the transformer is 200V