Graphs of Current through a Transformer

In summary, the conversation revolved around the creation of a make-shift transformer using a circular core and wire. The speaker had questions about the sharp spike in current observed when passing 220V AC current through one side of the transformer. They initially predicted that the induced current would also be a sine wave, but upon seeing the spike, they theorized that it was due to the changing magnetic field. It was then revealed that the speaker was actually measuring voltages and that the core flux was flat-topped, indicating saturation and high magnetizing current. The conversation ends with a warning about the dangers of playing with 220V mains voltage and the importance of proper supervision.
  • #1
lekh2003
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I have created a make-shift transformer using a circular core and some wire:
4efe9cf1-0016-4fe4-bac0-b0da846b6f48.jpg


It is quite basic, but I have some questions about the currents induced when one side of this transformer has a 220 V AC current passed through it.

I have an oscilloscope from which I have the graph:

41343cfc-2ce1-4acc-a93f-635bee6f3368.jpg

The perfect sine wave is the input current (220 V). I am just wondering why the induced current (the other side of the transformer) has such a sharp spike in the current. My initial prediction was that the induced current would also be a sine wave.

Then, when I saw the spike, I thought that there was a spike because the magnetic field is changing most when the current completely changes direction (When the sine wave intersects with x-axis). Am I right?
 

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  • #2
What did you connect across the secondary (i.e. the other side of the transformer)?
 
  • #3
Directly to the oscilloscope to check the voltage going through.
 
  • #4
lekh2003 said:
Directly to the oscilloscope to check the voltage going through.
You are actually measuring voltages here. The sinusoidal waveform is your mains voltage. From the secondary voltage graph (the spikey waveform), it appears that the core flux is flat-topped with a lot of harmonics.
If the core flux is flat-topped, the core is saturated and is drawing very high magnetizing current.

Check the resistance of the primary coil.
 
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  • #5
@lekh2003, your profile says you are only 14. I believe it is very dangerous for you to be trying anything on 220V ac mains.
Be very careful and do everything under proper supervision.
 
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  • #6
The thread will remain locked.

PF does not allow public discussion of dangerous topics. Playing with 220V mains voltage certainly qualifies as dangerous. The OP is encouraged to continue his curiosity, but to choose his experiments with safety foremost.
 
Last edited:
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Related to Graphs of Current through a Transformer

1. What is a transformer?

A transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction. It consists of two or more coils of wire, known as the primary and secondary windings, which are wrapped around a common iron core.

2. How does a transformer work?

A transformer works on the principle of electromagnetic induction. When an alternating current flows through the primary winding, it creates a changing magnetic field which induces an alternating current in the secondary winding. The ratio of the number of turns in the primary and secondary windings determines the output voltage and current.

3. What is the purpose of a graph of current through a transformer?

The graph of current through a transformer is used to visualize the relationship between the input and output currents in a transformer. It helps in analyzing the performance and efficiency of the transformer by showing the changes in current over time.

4. How does the current through a transformer vary with load?

The current through a transformer varies with load due to the ratio of the number of turns in the primary and secondary windings. As the load on the secondary side increases, the current also increases in order to maintain the same output voltage. This is known as the transformer's load regulation.

5. What factors affect the graph of current through a transformer?

The factors that affect the graph of current through a transformer include the number of turns in the primary and secondary windings, the frequency of the alternating current, the core material and design, and the load on the secondary side. These factors can affect the transformer's efficiency, voltage regulation, and current-carrying capacity.

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