Transformer question (between substation and home)

  • Thread starter Thread starter blooperkin
  • Start date Start date
  • Tags Tags
    Home Transformer
AI Thread Summary
To determine the turn ratio for an ideal step-down transformer delivering 100kW of power at 240V from a 10kV source, the primary current is calculated to be 10A, leading to a voltage drop of 100V across the resistance in the primary circuit. This results in a primary transformer voltage of 9900V. The power output at the secondary circuit is equal to the power input at the primary, calculated as 99000W. The discussion raises questions about the nature of the secondary coil's resistance and the load presented by the home, which is treated as a resistive element in the circuit. The key challenge lies in finding the potential difference across the secondary coil to apply the turn ratio formula effectively.
blooperkin
Messages
8
Reaction score
0

Homework Statement


A power station generates 100kW of power at a voltage of 10kV. Given that the connecting cables in the primary and secondary circuit each have a resistance of 10Ω, find the turn ratio required for an ideal step-down transformer to bring electrical energy to the home at 240V.

Homework Equations



Turn ratio:
Ns/Np = Vs/Vp = Ip/Is
(s- secondary coil, p- primary coil)

V = IR
P = V^2/R = IV = I^2R

The Attempt at a Solution


For the primary circuit,
Current = 100000/10000 = 10A
Potential difference across 10Ω resistance = 10*10 = 100V
Potential difference across primary transformer = 10000-100 = 9900VI know the power across both transformer coils must be equal, so:
Power output at secondary circuit = Power input at primary coil = 9900*10 = 99000W

- What does this 99000W refer to? The power across the secondary coil or the power across the whole secondary circuit?
- Or does the secondary coil act like cell in the secondary circuit? ie. Do I have to consider its resistance?
- Does the home act like a lightbulb in a circuit? So it has a resistance?

I'm stuck here because I can't find the potential difference across the secondary coil to use the turn ratio formula.

Diagram of secondary circuit:
fks0og.jpg
 
Physics news on Phys.org
The power is going somewhere, so yes, assume the home load (resistance) is R. What equations can you write down?
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...

Similar threads

Back
Top