10/1 step down tranformer, resistance, power loss of secondary coil

In summary, the problem involves finding the resistance of the secondary coil and the power loss in the secondary coil of a 10/1 stepdown transformer with a full load secondary current of 50A and a rating of 30kVA. The copper loss at full load is 280W and the primary winding has a resistance of 0.25ohms, while the core losses are 120W. To calculate efficiency at the rated load with a power factor of 0.92, the formula is Efficiency = (Power Output / Power Output + Copper Loss + Core Loss) x 100. The first step is to determine the power output using the definition of power (P = V x I). Then, the power loss in
  • #1
whitelockben
5
0

Homework Statement



A 10/1 stepdown tranformer has a full load secondary current of 50A and is rated 30kVA. The copper loss at full load is 280W. The primary winding has a resistance of 0.25ohms. The core losses are 120W.

Find the resiatance of the secondary coil and the power loss in the secondary coil. Calculate the efficience at the ratedl oad when a power factor of 0.92 exists.


Homework Equations



Have no got a clue but during a search of the internet I found this which I am not sure is correct ...

Efficiency = Power Output
------------------------------------ x 100
Power Output Copper Loss Core Loss

The Attempt at a Solution



have no got a clue..



Hi there, I'm just hoping some one has time to post a solution to this problem and all show the working, I'm sure I would be able to work out what has been done if the working is shown..
Thanks in advance

Ben
 
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  • #2
whitelockben said:

Homework Statement



A 10/1 stepdown tranformer has a full load secondary current of 50A and is rated 30kVA. The copper loss at full load is 280W. The primary winding has a resistance of 0.25ohms. The core losses are 120W.

Find the resiatance of the secondary coil and the power loss in the secondary coil. Calculate the efficience at the ratedl oad when a power factor of 0.92 exists.


Homework Equations



Have no got a clue but during a search of the internet I found this which I am not sure is correct ...

Efficiency = Power Output
------------------------------------ x 100
Power Output Copper Loss Core Loss

The Attempt at a Solution



have no got a clue..



Hi there, I'm just hoping some one has time to post a solution to this problem and all show the working, I'm sure I would be able to work out what has been done if the working is shown..
Thanks in advance

Ben

Well, we sure as heck do not do your homework for you here. Take a shot at using what you are given... You are given some voltages, currents, resistances, powers, etc. What is the definition of power in terms of V and I? And overall efficiency is power out divided by power in. What are the different sources of loss, and what order are they in (first, second, etc.)?
 
  • #3
jamin



Hello Benjamin,

Thank you for reaching out for assistance with this problem. Let's work through it together and hopefully I can provide some clarity for you.

First, let's define some of the terms given in the problem:

- Stepdown transformer: This is a type of transformer that decreases the voltage from the primary winding to the secondary winding. In this case, the ratio is 10/1, meaning the secondary voltage is 1/10th of the primary voltage.

- Secondary coil: This is the winding of the transformer that receives the power at a lower voltage.

- Resistance: This is the measure of how much a material resists the flow of electric current. In this problem, we are given the resistance of the primary winding and we need to find the resistance of the secondary winding.

- Power loss: This is the amount of power that is lost due to various factors, such as resistance and core losses.

Now, let's work through the problem step by step.

1. Find the resistance of the secondary coil:

To find the resistance of the secondary coil, we can use Ohm's law: R = V/I, where R is resistance, V is voltage, and I is current. We are given the full load secondary current (50A) and the rated power (30kVA). We can calculate the voltage using the formula P = VI, where P is power, V is voltage, and I is current. So, V = P/I = 30,000/50 = 600V.

Now, using the given resistance of the primary winding (0.25ohms) and the voltage ratio (10/1), we can use the formula R2/R1 = (V2/V1)^2 to find the resistance of the secondary coil. Plugging in the values, we get R2 = (600/10)^2 * 0.25 = 90ohms.

2. Find the power loss in the secondary coil:

To find the power loss in the secondary coil, we can use the formula P = I^2R, where P is power, I is current, and R is resistance. We are given the full load secondary current (50A) and the resistance of the secondary coil (90ohms). Plugging in the values, we get P = (50)^2 * 90 = 225,000W or 225kW.

3. Calculate the efficiency:

To calculate
 

1. What is a 10/1 step down transformer?

A 10/1 step down transformer is a type of electrical transformer that has a lower number of turns in the secondary coil compared to the primary coil. This results in a lower output voltage than the input voltage.

2. How does a step down transformer work?

A step down transformer works by using electromagnetic induction to transfer energy from the primary coil to the secondary coil. The primary coil is connected to an alternating current (AC) power source, which creates a changing magnetic field. This changing magnetic field induces a current in the secondary coil, resulting in a lower output voltage.

3. What is the purpose of a step down transformer?

The purpose of a step down transformer is to decrease the voltage of an AC power source to a level that is suitable for use in electronic devices. This is necessary because most electronic devices operate on lower voltages than the standard voltage of AC power sources.

4. How does resistance affect a step down transformer?

Resistance affects a step down transformer by causing power loss in the secondary coil. This is because resistance converts electrical energy into heat, resulting in a decrease in the efficiency of the transformer. Lower resistance in the secondary coil will result in less power loss and more efficient operation.

5. What is power loss in a step down transformer?

Power loss in a step down transformer refers to the amount of energy that is lost during the transformation process. This can be caused by various factors, such as resistance in the secondary coil, eddy currents, and hysteresis. Minimizing power loss is important for improving the efficiency and performance of a transformer.

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