Question

Describe any two energy losses occurring in transformers. How these can be minimized?
Why electric power is transmitted at high voltage upto large distances?

Answer 1

Transformer is a static device, i.e. we do not get to see any movements in its parts, so no mechanical losses exist in the transformer and only electrical losses are observed. So there are two primary types of electrical losses in the transformer:

1) Copper losses

2) Iron losses

1) Copper losses

These losses occur in the windings of the transformer when heat is dissipated due to the current passing through the windings and the internal resistance offered by the windings.

2) Iron losses

These losses occur in the core of the transformer and are generated due to the variations in the flux. These losses depend upon the magnetic properties of the materials which are present in the core, so they are also known as iron losses, as the core of the Transformer is made up of iron. And since they do not change like the load, so these losses are also constant.

The above losses can be minimized by,

1) It can be done by using superior quality material for CORE like CRGO STEEL,Si-Steel.This reduces the very high conductivity of core.Reason to reduce is eliminate unwanted eddy currents or circulating currents.

2) Maintaining the CONSTANT FLUX DENSITY in core,so that (v/f = constant ).

3) Consequences for change in freq are less compared to change in voltage.therefore when it is needed to change voltage it is manditory to change freq too.

4) Operating transformer near to ideal characteristics.

We need high voltage line because,

Wire resistance causes losses in eletric power transmission. If you keep resistance constant, losses are linearly proportional to voltage, but proportional to the square of the current. So if you double the voltage, for the same power you have half the current, and power dissipation is effectively halved for the same power.

Another important reason is weight. In order to transmit more current, and keep losses under control, one would need a bigger wire, with a larger sectional area. Such a wire would weight a lot more than the thinner wire that can transmit lower currents. Heavier cables use more metal, are more expensive, and limit the cable span (the distance between the towers), requiring more towers to be transmitted over the same distance.