Question:

Transformers.?

A step up transformer has 5,000 turns in the secondary coil and 200 turns in the primary coil. The primary is supplied with alternating current with an effective voltage of 900V. (A) What is the voltage in the secondary coil? (B) If the current in the secondary coil is 20A, what current flows in the primary coil? (C) What power is developed in the primary coil? (D) What power is developed in the secondary coil?

Answer:

A step up transformer has 5,000 turns in the secondary coil and 200 turns in the primary coil. N1 200 turns N2 5000 turns The primary is supplied with alternating current with an effective voltage of 900V. V1 900V (A) V2 ? V2 N2 / N1 x V1 V2 5000 / 200 x 900 25 x 900 22,500V (B) I2 20A ; I1 ? V1 x I1 V2 x I2 I1 (V2 x I2) / V1 I1 (22500V x 20A) / 900V I1 500 A (C) P1 ? P1 V1 x I1 P1 900V x 500A 450,000W (D) P2 ? P2 V2 x I2 P2 22,500V x 20A 450,000W Yep, the power in the primary is equal to power in the secondary.
a) (5,000/200) x 900V 22,500V. (5,000/200) 25:1. b) (20 x 25) 500A. c) (900 x 500) 450,000W. (22,500 x 20) 450,000W. (450KW). Both must be the same, if no losses.

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