Exploring Transformers: I^2R Power Losses

In summary, the conversation discussed how transformers can minimize power losses in transmission cables by stepping up voltages and stepping down currents. The concept of V2/R and its relation to power losses was also clarified, with the understanding that the voltage drop across the wires is proportional to the current flowing through them. This understanding is important when considering the power loss in transmission lines.
  • #1
aznking1
16
0

Homework Statement


Ok so i was doing my revision for my exams and i was reading on transformers and they said that stepped-up Voltages and stepped-down currents minimizes for tranformers I^2R power losses in the transmission cable. I know that current is decreased, but a higher voltage, by V^2/R, would also mean a greater power loss?

The Attempt at a Solution


I know there have been similar questions like this one below.

physicsforums. com/showthread.php?t=227834( there's a space at the .com cause i can't post links yet)

But i do not understand their reasoning. For example stewartcs said that problem with this line of reasoning is that P = IV is the power delivered by an electrical energy source not the power dissipated by it.

Also the person who asked the question said that he was mixing up the supplied nominal V of the power lines with the V lost by the resistance.

i do not really understand what both of them are saying. can anyone explain it to me? thanks!
 
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  • #2
V2/R means the voltage drop at the resistor/appliances NOT the supply voltage.
Less current means less voltage drop whereas the resistance remained.
 
  • #3
azizlwl said:
V2/R means the voltage drop at the resistor/appliances NOT the supply voltage.
Less current means less voltage drop whereas the resistance remained.

no but if u increase the supply voltage won't the voltage drop across the wires also increase? Like for example you increase the voltage of a battery the voltage drop across the resistor increases
 
  • #4
aznking1 said:
no but if u increase the supply voltage won't the voltage drop across the wires also increase? Like for example you increase the voltage of a battery the voltage drop across the resistor increases

No, not if you step up the voltage for transmission and step it down again at the other end for delivery to the load; The majority of the voltage drop appears across the transformer windings at each end of the transmission loop. The power lost is the power dissipated in the transmission wires due to the current flowing through the resistance of the transmission wires.

Yes this current produces a voltage drop in that transmission wire resistance, but due to Ohm's Law that voltage drop is proportional to the current: V = IR. If the current is smaller, then the voltage drop will be smaller. You could use this transmission line voltage drop to calculate the power loss with V2/R, but since this voltage drop is due to the CURRENT flowing in the transmission lines, it's more natural to work with the I2R form.
 
  • #5
gneill said:
No, not if you step up the voltage for transmission and step it down again at the other end for delivery to the load; The majority of the voltage drop appears across the transformer windings at each end of the transmission loop. The power lost is the power dissipated in the transmission wires due to the current flowing through the resistance of the transmission wires.

Yes this current produces a voltage drop in that transmission wire resistance, but due to Ohm's Law that voltage drop is proportional to the current: V = IR. If the current is smaller, then the voltage drop will be smaller. You could use this transmission line voltage drop to calculate the power loss with V2/R, but since this voltage drop is due to the CURRENT flowing in the transmission lines, it's more natural to work with the I2R form.

oh ok thanks for your help i get it now!
 

Related to Exploring Transformers: I^2R Power Losses

1. What are I^2R power losses in transformers?

I^2R power losses, also known as copper losses, are the energy losses that occur in a transformer due to the resistance of the transformer's windings. These losses are caused by the flow of current through the windings and result in the generation of heat.

2. How do I^2R power losses affect transformer efficiency?

I^2R power losses decrease the efficiency of a transformer by converting electrical energy into heat energy instead of delivering it to the load. This heat must be dissipated by the transformer, which can lead to overheating and potentially damage the transformer if not properly managed.

3. What factors contribute to I^2R power losses in transformers?

The two main factors that contribute to I^2R power losses in transformers are the resistance of the windings and the magnitude of the current flowing through them. Other factors include the design and construction of the transformer, as well as the quality of the materials used.

4. How can I reduce I^2R power losses in transformers?

I^2R power losses can be reduced by using materials with lower resistance for the transformer windings, such as copper instead of aluminum. Proper design and construction techniques can also help to minimize these losses. Additionally, using a transformer with a higher efficiency rating can help to reduce I^2R power losses.

5. Why is it important to consider I^2R power losses in transformer design?

Considering I^2R power losses in transformer design is important because it directly affects the efficiency and performance of the transformer. High power losses can lead to overheating, decreased efficiency, and potential damage to the transformer. By minimizing these losses, the transformer can operate more efficiently and reliably.

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