The power lines that carry extremely high voltages have been certainly noticed by you. They can be seen as crisscross lines along the countryside. However, some are laid beneath city streets. Till now, you may have also learned that they carry electricity from power plants to our homes, offices, schools, banks, and factories.
It may come as a surprise to a few people but it is not an extraordinary thing for a power line to be rated at 400,000 to 750,000 volts. But, the appliances we use in our homes require only low voltages of about 110 to 250 volts, which are surely thousands of times less than the ones running through power lines.
So, how do we reduce electricity at such enormously high voltages to a lower level so that it is safe to operate appliances in our homes? The equipment that is used to accomplish this task is called an electrical energy transformer. Let’s explore this topic in detail.
Why such high voltages are transmitted by power plants if we need such small value of voltages?
This question obviously comes to your mind when you learn about the facts explained above. To understand this, first, you need to know how electricity travels.
As electricity flows down the metal wire, the electrons that carry this electrical energy have to face a lot of hurdles in their path. Their journey is not smooth and there are a lot of bumps, for instance, collision with each other and with the surface of the metal. Consequently, they waste a lot of energy while jiggling through a metal structure. This is why wires get hot when electricity travels through them. Even though this heat energy is quite a desired element when you use appliances like toasters, it is not useful when we need to transmit electrical energy.
Since it turns out that the higher the voltage electricity you use and the lower the current, the less electrical energy is wasted in transmission. So, power plants transmit electricity at higher voltages just to save energy.
There is also another reason. Manufacturing plants have huge machines that require a great amount of power to operate, which is not even near the power you need at home. The energy a machine use is directly proportional to the voltage it uses. So, these machines may require high voltages, for instance, 10,000-30,000 volts. On the other hand, smaller workshops and factories may need supplies of only 400 volts or so.
It means that in the real world, different electricity consumers have different requirements. So, it makes complete sense to supply high voltage electricity from the power station and then reduce it to lower voltages accordingly.
Now, the question arises –how does an electrical energy transformer work?
The working of a transformer is based on the principle that when fluctuating current flows through a wire, it generates a magnetic field, an invisible pattern of magnetism. The strength of magnetism is directly related to the amount of current. The bigger the current, the stronger the magnetic field.
Another interesting fact about electricity is that when a magnetic field fluctuates through a piece of wire, an electric current is produced too. So, when we pass an electric current (primary current) through one coil which is placed near another coil, it will create an electric current (secondary current) in the nearby coil too. The process is usually called electromagnetic induction because the current in the first coil causes current in the second coil.
We can pass electrical energy with more efficiency from one coil to another by wrapping them around a soft iron bar, also known as the core. The coil is made by simply curling the wire round into loops or turns. If both coils have the same number of turns, the same amount of current will produce in the secondary coil. However, if we have more or fewer number of turns in the second coil, we can make the secondary current and voltage higher or lower than the primary ones.
One more thing you need to note is that it works only when electric current fluctuates and therefore, we have to use a type of constantly reversing electricity called alternating current with electrical energy transformers. They don’t work with direct current. This is how this equipment works.