Theory- 16 :- Transformer, Turn Ratio, Transformer Winding, Winding Machines

⚡ Transformers: The Basics

Imagine you have a toy car that needs a small battery (low voltage), but your wall socket gives out a lot of power (high voltage). You can't plug the car directly into the wall, right? You need something to "change" the power to the right level. A transformer is like that special charger for your toy car.   

A transformer is a device that changes the voltage of an electric current. It can either increase the voltage (step-up) or decrease it (step-down). The cool part is that it does this without any moving parts!    

How does it work? It works on a principle called mutual induction.

1. The Setup: A transformer has two sets of coiled wires, called windings, wrapped around a metal core (usually iron).

   • The Primary Winding is connected to the incoming power source.

   • The Secondary Winding is connected to the device you want to power.

2. The Magic: When AC (alternating current) electricity flows into the primary winding, it creates a changing magnetic field in the iron core.

3. The Transfer: This changing magnetic field then "induces" or creates a new electric current in the secondary winding.

Think of it like two people holding jump ropes next to each other. If one person starts swinging their rope (the primary winding's magnetic field), the air movement might cause the second person's rope (the secondary winding) to start swinging too, even without them touching.

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🔢 Turn Ratio: The Secret to Changing Voltage

So, how does a transformer know whether to step-up or step-down the voltage? The secret is in the number of turns in each winding. The Turn Ratio is simply the comparison between the number of turns in the secondary winding and the primary winding.

Let's say:

• Np = Number of turns on the Primary winding

• Ns = Number of turns on the Secondary winding

The rule is simple:

• To Step-Down Voltage (Decrease it): You need fewer turns on the secondary winding than the primary (Ns < Np). This is like a phone charger; it takes high voltage from the wall and steps it down to charge your phone.

  • Example: If the primary has 200 turns and the secondary has 100 turns, the voltage will be cut in half.

• To Step-Up Voltage (Increase it): You need more turns on the secondary winding than the primary (Ns > Np). This is used in power plants to send electricity over long distances at very high voltages.

  • Example: If the primary has 100 turns and the secondary has 200 turns, the voltage will be doubled.

An easy way to remember:

• More turns = More voltage

• Fewer turns = Less voltage

A key thing to remember is that while voltage changes, power stays almost the same. So, if voltage goes up, the current goes down, and vice versa. It's a trade-off!

$Voltage_{secondary} / Voltage_{primary} = Ns / Np$

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🧵 Transformer Windings: The Coils that Do the Work   

The windings are the insulated wires coiled around the transformer's core. They are the pathways for the electric current. The material and style of these windings are very important for the transformer to work well.

Winding Materials

• Copper: This is the best choice. It's a great conductor of electricity (like a super-smooth highway for electrons) and is very strong. You'll find it in most high-performance transformers.

• Aluminum: This is a lighter and cheaper option. It's not as good a conductor as copper, but it works well for many everyday transformers where cost is a factor.

Types of Windings

How you wrap the wire matters! Different styles are used for different jobs.

• Cylindrical/Layer Winding: This is the most common and simple type. Wires are wound in neat layers, one on top of the other, like thread on a spool. Good for low-voltage applications.

• Helical Winding: Imagine a spring or a helix. This style is used for transformers that handle high currents but at low voltage.

• Disc Winding: For very high-voltage transformers, the winding is made of several flat, disc-shaped coils stacked on top of each other. This helps to manage the high voltage safely and allows for better cooling.

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⚙️ Winding Machines: How Windings Are Made

You can't just wrap these wires by hand and expect them to work perfectly, especially for large transformers. Special machines are used to create precise and tight coils.

• Manual Winding Machines: A simple machine where an operator guides the wire onto the core, which is turned by a hand crank or a simple motor. It's good for making one-off transformers or for repairs.

• Automatic Winding Machines: These are computer-controlled machines. You just program the number of turns, the speed, and the spacing, and the machine does all the work perfectly every time. These are used in factories to make thousands of transformers quickly and accurately.