Transformer is a device used to step up and step down alternating voltages for our advantages. Transformers are the one of the most energy efficiency devices in the electrical world. When the transformer was discovered there were a lot of loops for energy losses. Since then there were researches on how to improve its efficiency. Transformer is an electrical device so there are chances for energy losses. Scientists have implemented different techniques and methods to improve its efficiency. Here we are going to discuss about different losses in a transformer and methods taken by scientists to increase transformer efficiency.
Losses in a Transformer
In a transformer there are different types of energy losses. Consider an ideal transformer. An ideal transformer is a transformer in which power in primary coil equals power in secondary coil.
Input power=output power
Vp Ip= Vs Is
But in actual practice input power slightly differes from the output power.
Different types of losses in a transformer
- Flux leakage
- Copper loss
- Eddy current loss
- Hysteresis loss
1. Flux leakage
We know that magnetic flux is the fundamental thing behind the working of a transformer. All the flux linked with the primary may not pass through the secondary coil. Thus energy losses in the form of leaked flux. We have to think how to reduce the energy loss due to flux leakage .It can be done by minimizing the flux leakage. That's why in some efficient transformers, primary coil and secondary coil winds one over the other. Thus almost all the flux produced by the primary coil will cut the secondary coil.
2. Copper loss
Every conductors ,even super conductors have certain amount of resistance at room temperature. Transformers uses copper wires, which causes some energy loss as heat.
There are two types of copper losses, primary coil loss and secondary coil loss. The power loss may be varied according to the load on the transformer.
3. Eddy current loss
When conductors are subjected to change in magnetic flux, induced currents are produced in them like circular loops termed as eddy current. The alternating magnetic flux induces eddy current in the transformer core. The circulating current produced in the transformer core do not contribute in output of the transformer and dissipated as heat on transformer core. Thus a large heat will generate at the core of the transformer.
4. Hysteresis loss
Some energy losses as heat during the magnetizing and demagnetizing process of the core. The core of the transformer is made of cold rolled grain oriented silicon steel. We know that steel is a good ferromagnetic material. Ferromagnetic materials have a property, that is they are very sensitive to magnetic field. If they are placed in a magnetic field the magnetic domains in the ferromagnetic material arrange themselves in parallel to the axis of applied field. After removing the external field maximum number of domains inside the material come to random positions. But because of some unchanged domains the core substance become slightly magnetized permanently. This remaining magnetism is known as spontaneous magnetism. To neutralize this spontaneous magnetism some opposite magneto motive force is required to be applied. Due to this domain reversal there will be extra workdone, which causes consumption of electrical energy and it is known as hysteresis loss.
Methods of reducing losses in a transformer
1. How to reduce the energy loss due to flux leakage?
Energy loss due to flux leakage has overcame by placing secondary coil above the primary coil. This ensures all the field lines from the primary coil will cut the secondary coil.
2. How to reduce copper loss?
It not easy to reduce copper loss. Because every materials have certain resistance. In transmission lines copper loss can be reduced by increasing the diameter of the wire used. But in a transformer it is not applicable.
3. How to reduce Eddy current loss?
It is possible to reduce energy loss due to eddy current by laminated core. The laminated core means the core is sliced and each piece is laminated from the next and it cuts the path of eddy current. Laminated core reduces the possibility for generating eddy current and heat dissipation.
4. How to reduce hysteresis loss in a transformer?
Hysteresis losses are depends on B max,frequency, and material. So it was hard to reduce hysteresis loss. Now a days there are modern transformers which uses amorphous form of silicon steel. In amorphous silicon steel metal grains are microscopic, which helps to keep hysteresis loss very low. That is the only way to reduce hysteresis loss is by changing the core material. Special allows known as "prem alloy" is also used to minimize transformer hysteresis loss.
By implementing such methods transformers are now listed in most efficiency devices. We can't imagine a day without transformers!!! Do you know why???