Thursday, 29 August 2013

Why Supply Frequency Is Either 50 Hz or 60 Hz ??

Ever wondered why the supply frequency is kept fixed at 50 Hz or at 60 Hz. yes the probably answer everyone would give is for the sake of uniformity, or it is adopted as a standard to have an understanding between the consumers and the generation side. Yes I agree completely, and I am giving a table of power frequencies used by some nations:

Here if you have observed the supply frequency is fixed to two values, either 50 or 60. The real question is why 50 or 60 only, why not 75 or 100 Hz??

The reason is because of the limitations of synchronous generators. We use synchronous generators (AKA turbo alternators) in thermal plants. The turbines of these turbo alternators have maximum efficiency at 3000 rpm to 3600 rpm. So when we calculate the frequency, (min of 2 poles) we get f= 50 or 60.

frequency, f = PNs / 120

P = no. of poles
Ns = Synchronous speed in rpm

The poles are suitably reduced to 2, because a large number of poles means, larger diameter of the rotor, which in turn means more centrifugal forces are developed during such high speed rotation.

And we all know most of the power plants are thermal based. 

Hence the power frequency is fixed at either 50 Hz or 60 Hz.

Wednesday, 7 August 2013

Michael Faraday

Michael Faraday is known as the father of electrical engineering because of his numerous contributions to the growth of the branch. If it wasn't for this man we wouldn't be having our induction generators, electrical energy meters, or even transformers or anything that works on the principle of induction.

This Michael Faraday was a third out of the four children in his family, received fairly little amount of education. But he had an enthusiasm to read while he was under the apprenticeship under a bookbinder. Then later on he worked at a chemistry lab, then in a physics lab. While working in the physics lab he accidentally noticed how a shock was felt when he moved a coil through the magnetic field, later the phenomenon was known as Mutual Induction (electromagnetism and Self-induction were known at the time ). Faraday made the first model of a generator, (which we learn in the seventh grade).

The unit of Capacitance is given as farad in honour of Faraday, as per Maxwell's words "Faraday was a mathematician of a very high level from whom the future mathematicians will learn much valuable and fertile methods".

Mr. Faraday also had contribution in chemistry discovering two new elements Carbon and Chlorine. He also developed a rough model of a Bunsen burner, compounds like Benzene. He has contributed much towards electrolysis and the properties of colloids.

Coming to the contributions in electricity and magnetism, he was the first one to notice diamagnetism.

Faraday also discovered that the plane of polarization of linearly polarized light can be rotated by the application of an external magnetic field aligned in the direction which the light is moving. This is now termed the Faraday effect. He wrote in his notebook, "I have at last succeeded in illuminating a magnetic curve or line of force and in magnetising a ray of light".