Twin Electric

Why is a step-down transformer used instead of a resistor for reducing high voltage? For example: If input voltage is 230V and we have to step down the voltage, can we use a resistor instead of transformer? If we cant, can any one explain the drawbacks?

The first person to observe current eddies was François Arago (1786–1853), the 25th Prime Minister of France, who was also a mathematician, physicist and astronomer. In 1824 he observed what has been called rotatory magnetism, and that most conductive bodies could be magnetized; these discoveries were completed and explained by Michael Faraday (1791–1867).

Transformer Losses (Heat)

The thermal ratings of a transformer are determined by the following three factors:

1. The amount of heat produced in the wingdings and connections.
2. The amount of heat produced in the iron core.
3. How effectively the heat can be removed from the transformer when the thermal rating of the transformer is reached. At this point, the heat being produced must equal the heat being removed or dissipated – thermal equilibrium.

Varnishing ...

DO YOU KNOW ? WHY VARNISH IS USED ?

Fibrous material, such as paper, was traditionally used as the primary insulation on inductor coils. To improve the insulation properties of the coils without having to use wire with thicker insulation, a secondary insulation (i.e. impregnation resin) was used to "impregnate" the assembled coils of wire.

Primary insulation is considered impregnated when all the spaces and gaps between fibers are completely filled by the impregnation resin, which is why secondary insulation and impregnation resin are interchangeable terms. By this definition, a winding can be impregnated even if there are still spaces between coils--as long as the spaces between the fibers of the primary insulation are filled in.

Insulating varnish refers to the electrical insulation used for impregnating coils of wire, such as the inductor coils found in transformers. It is also known as impregnating or transformer resin.

Keep in mind that insulating varnish may refer to the primary insulation (wire enamel) used to initially coat a bare conductor, or it may refer to the secondary insulation that is applied to assembled windings of enameled wire.