An audio product company needs a 50 Hz step down transformer with 125 kVA power in the primary winding. The voltage ratio of the transformer is 1100/220 V with 120 turns on its sec... An audio product company needs a 50 Hz step down transformer with 125 kVA power in the primary winding. The voltage ratio of the transformer is 1100/220 V with 120 turns on its secondary winding. Calculate the number of turns of the primary winding and the currents that would flow in both the windings when fully loaded.

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Understand the Problem

The question is asking to calculate the number of turns in the primary winding of a transformer and the currents that will flow in both windings when it is fully loaded, given certain parameters including power and voltage ratio.

Answer

The primary winding has \( N_p = 600 \) turns, with \( I_s \approx 568.18 \, A \) (secondary) and \( I_p \approx 113.64 \, A \) (primary).
Answer for screen readers

The number of turns in the primary winding is ( N_p = 600 ) turns. The currents flowing in the windings when fully loaded are ( I_s \approx 568.18 , A ) (secondary) and ( I_p \approx 113.64 , A ) (primary).

Steps to Solve

  1. Calculate the Turns Ratio The turns ratio of the transformer can be found using the voltage ratio. Given that the primary voltage ( V_p = 1100 , V ) and the secondary voltage ( V_s = 220 , V ), the turns ratio ( n ) is given by:

[ n = \frac{V_p}{V_s} = \frac{1100}{220} = 5 ]

  1. Calculate the Number of Turns in the Primary Winding The number of turns in the primary winding can be calculated using the turns ratio and the known secondary turns. Let ( N_s = 120 ) (turns in the secondary). The formula is:

[ N_p = n \times N_s = 5 \times 120 = 600 ]

  1. Determine the Current in the Secondary Winding First, we calculate the apparent power ( S ) in VA:

[ S = 125 , kVA = 125000 , VA ]

Next, calculate the secondary current ( I_s ) using the formula:

[ I_s = \frac{S}{V_s} ]

Substituting the values:

[ I_s = \frac{125000}{220} \approx 568.18 , A ]

  1. Determine the Current in the Primary Winding Using the transformer current relationship, we can find the primary current ( I_p ):

[ I_p = \frac{I_s}{n} ]

Substituting the values:

[ I_p = \frac{568.18}{5} \approx 113.64 , A ]

The number of turns in the primary winding is ( N_p = 600 ) turns. The currents flowing in the windings when fully loaded are ( I_s \approx 568.18 , A ) (secondary) and ( I_p \approx 113.64 , A ) (primary).

More Information

Transformers are essential in electrical systems, converting voltage levels while maintaining power. The turns ratio directly impacts the current in both windings.

Tips

  • Not accounting for the power factor when calculating currents: This problem assumes a purely resistive load for simplicity.
  • Confusing the roles of primary and secondary voltages, which can lead to incorrect calculations of turns and currents.

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