Why electricity generate in multiples only 11(like that 110 , 220 vac 44o vac)?

Question

AC voltage 110 , 220 , 440 v 33 kva 110 kva 220 kva 440 kva

Answer 1

It simplifies the design of transformers.

High Voltage lines carry electricity at high voltages.  When it reaches your immediate neighborhood, it is stepped down to two wires each with 110 volts each and a third that is a ground.  That is the function of the canister high up on the pole.

Three wires go to your home, two with 110 voles out of phase with each other and the third a ground.  Typically the circuits in your home are divided into two different areas, each area for one of the "hot" 110 volt wires and the ground.  You also have a house ground, the third plug hole in the socket, not to be confused with the ground coming from the electric company.

Where you have appliances that require 220 volts the two wires are combined together.

If the line to your house get struck by lightening, as the line going to my house did six years ago, it is common for only one of the two "hot" wires to be wasted.  So you end up with half of your house receiving electricity and the other half not.  Until the repairman from the Electrical Company arrives and fixes things.

Answer 2

It's not.

120/240, (called 110/220),  is a common size for for

single phase center tapped residential service.

That's what you commonly see, but it's not how power

is generated or transmitted.

Most power is generated as three phase power where

the ratio is 1: Sq.Rt. 3  instead of  1:2.

(Eg. 120/208, 277/480, 2400/4160 .....)

Answer 3

First I want to disagree, electricity is not generated in multiples of 11. In truth, in the US AC power is generally produced in factors of 2, but do to resistance it is reduced to a factor lower that. How much lower depends on the resistance which found in the delivery system. For an AC current, electricity is transformed down to 120 volts but the 110 volt rating is used only as an average at which electricty is recieved and usable. and it varies between a useable factor of 100v and 120v.

As for why there is a factor of 2, it has to do with dual phase production of electricity and the devevery system. A single phase generator exists but is very inefficent in production. A dual phase generator is much more effectient and safer form of production and delivery. A dual phase generator produces opposing waves which serve as a damper to each other should a short occur (in-phase would amplify the voltage).

It also has to do with the transformation of electricity and the calculation of the charge rate (2 is a very simple number to work with).

There are many other factors involved with this and would require much more complex explanation.

Answer 4

Electricity is produced by generators as 3phase supply (in 3 phases). Each phase shifted by 120degress ahead or behind from each of the other two. Most small homes get supply from one phase; the 3 phases are distributed to (say) three blocks in city. Between any 2 phase wires the supply is 400 V (in India) or 200 V (in America). When supplied to a home, a pair of wires draws electricity; one connected to a 'phase' wire and the other a 'neutral' wire that is neutral between all the 3 phases.

The voltage across this phase and neutral is

400/ sqrt3 = 230 V (India),

200/ sqrt3 = 115 V (America).

It is kept not less than 220 V or 110 V by regulations. And hence the tag 220, 110 etc.