Step Down Transformer Working Principle: In our house, we use 120V-240V lines. The standard home supply voltage is 220V. If you have an electricity distribution idea, I guess you know electricity transmission requires high voltage-low current transmission for proper efficiency.
The maximum transmission voltage is 33KV (33000Volt). This is huge, right? Meanwhile, we are using 220V at our home! How are we actually able to do that? Here is the thing, we use a transformer to do that.
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What Is Step Down Transformer
If you already know what Transformer is, then it will be easy to understand Step Down Transformer. Step Down Transformer is an electrical device that reduces electrical voltage using electromagnetic induction. There are two winding in a step-down transformer: primary winding, secondary winding. In a step-down transformer, primary winding has fewer coils turns than secondary winding.
How A Step-Down Transformer Works
Usually, transformers work following mutual induction theory that follows a standard flux between two or more magnetic circuits. If two coils are placed on a magnetic core, one is the primary coil, and the other is the secondary coil.
When we supply AC voltage to the primary coil, following the Electromagnetic induction rule, the flux will move between the cores from the primary to the secondary winding. The power we get from the secondary winding to the secondary coil is our output.
Step Down Transformer Working Principle
Now, if there is another coil on that core, this moving flux will cut it, and the voltage will be absorbed in that coil, whose value is N (the number of turns of the coil). We have learned from the principle of electromagnetic induction and Faraday that only when there is relative motion between the magnetic field and the conductor or coil, that is, when the flux is cut in the conductor, the voltage in the conductor or coil is absorbed.
Here the relative motion of the magnetic field is not caused by the physical movement but by the AC supply, which is creating a variable magnetic field, cutting another coil, and absorbing voltage and current in it.
The first coil produces a moving or variable flux with AC supply voltage (Vp), which cuts the second coil and absorbs the voltage (Vs) between the second coil. The first coil is called the primary coil, and the second coil is called the secondary coil.
There is no electrical connection between the primary and secondary coils. How much voltage will be absorbed in the secondary coil depends mainly on the number of turns of the coil!