Transformers Coursework- Interpretation?

[kisqwer]

did an investigation on Transformers- something I thought would be a good idea. The aim was to find out how the amount of resistance put onto the transformer affects the power loss. By having a step-up transformer 300 turns on the primary and 600 turns on the secondary, then by connecting a resistor to the secondary coil (this was the independent variable and was changed: 1, 2, 5, 10, and 200 Ohms). I measured the Voltage and current on the primary coil, and the voltage and current of the secondary coil.

The following were the recorded measurements (the units are Ohms, Volts, Amperes):

Resistor Ohm| Primary volt| Primary current| Secondary volt| Secondary current
5 | 5.43 | 0.43| 1.16| 0.2
10 |5.42 |0.42| 2.24| 0.2
1 |5.42 |0.43| 0.27| 0.21
2 |5.44 |0.44| 0.5| 0.21
200 |5.42 |0.08| 10.15| 0.03

So I calculated the Power in, Power Out- and therefore the amount of power in percentage still present after the transformation
P in P out Pin/Pout *100
2.3349 0.232 9.936185704
2.2764 0.448 19.6801968
2.3306 0.0567 2.43284991
2.3936 0.105 4.386697861
0.4336 0.3045 70.22601476

My question is how do I interpret these results... (as now I am in doubt as if they make an y sense at all). As theoretically the current should decrease, and the voltage should increase in an up-step transformer. However the results suggest that as the resistance on the secondary coil is increased...the voltage increases..however the current stays the same (except at 200 Ohm resistance). I tried looking for some theory and equations on this topic but couldn't find anything. The results also suggest that as the resistance is increased the power loss is decreased. So if anyone could give me any pointers, explanations or just any input.

By the way when the secondary voltage was measured with no resitor connected it came out to be: 10.46V so about double of the input voltage of about 5V.

 

[jbsteele]

A good way to interpret these results is to look at the Power in and Power out values. The power in is the ratio of the voltage and current multiplied together on the primary coil. The power out is the ratio of the voltage and current multiplied together on the secondary coil. By dividing the Power in by the Power out and multiplying by 100, you can get a percentage of how much power was lost in the transformation. Since this is an up-step transformer, the voltage should increase and the current should decrease when resistance is added. This is what we can see in the results. As the resistance increases, the power loss decreases. The highest power loss occurs when no resistor is connected, with a 70.23% power loss, and the lowest power loss occurs when 200 Ohms of resistance is connected, with a 2.43% power loss. Another way to interpret these results is to look at the voltage and current values on the primary and secondary coils. As the resistance increases, the voltage on the secondary coil increases and the current on the primary coil stays the same. This means that more energy is being transferred from the primary coil to the secondary coil, and less energy is being lost.

 

[nlightner]

I would first like to commend you for conducting this investigation on transformers. It is a complex and important topic in the field of electrical engineering.

From your results, it seems that there is a relationship between the amount of resistance on the secondary coil and the power loss in the transformer. As the resistance increases, the power loss decreases. This can be seen in the calculated values of Power In/Power Out percentage, which decreases as the resistance increases.

One possible explanation for this is that as resistance is added to the secondary coil, it limits the flow of current through the coil. This results in a decrease in the amount of power lost in the form of heat. This is known as the "load effect" in transformers.

Additionally, your results also show that as the resistance increases, the secondary voltage also increases. This is expected in a step-up transformer, as the voltage on the secondary coil is proportional to the number of turns on that coil. The increase in voltage can be seen in the last row of your table, where the secondary voltage is almost double the primary voltage.

It is also important to note that your results may vary depending on the quality and type of transformer used. Theoretical predictions may not always match experimental results due to factors such as resistance in the wires, losses in the core material, and other practical considerations.

In terms of further research, you could explore the relationship between the resistance on the secondary coil and the efficiency of the transformer. This could provide a better understanding of how different resistances affect the overall performance of the transformer.

Overall, your results suggest that there is a correlation between the amount of resistance on the secondary coil and the power loss in the transformer. Further investigation and analysis can help to better understand this relationship and its implications.