why do different countries have different frequencies of electricity and why are the plugs shaped different?

Question

Are the shapes diff as a result of the frequencies? to differenciate? and what's the point of having different frequencies? is it a question of "newer" or more industrialized coutnries having lower frequencies or the other way around?

Answer 1

A number of reasons.

First, Thomas Edison practically invented the American electrical system, using Direct Current. For others to use his version of the light bulb, switches, etc they would either have had to license his designs or just steal them. It was easier to use the same ideas and modify them so much he could not claim patent infringement.

Second, when AC power was found to be much better than DC power, there was a debate as to what voltage to use.
The USA used 110 as it is pretty hard to kill yourself with it. Most of the world used 220 as it is far more efficient. To ensure people did not go plugging things into the wrong outlet, they made the plugs different.

Third, the USA used 60 cycle as that seemed logical. 1 Hour = 60 minutes, 1 Minute = 60 seconds, 1 Second = 60 cycles. Easy to do when you only get power out of 1/3rd of each cycle. Europe however was using 220 and thus getting power out of 2/3rds of a cycle. They found a slightly lower cycle rate worked better so went with 50 cycle.

Fourth, whoever helped a third world nation install their power grid tended to use what they had at home. That way they had an export market for their toasters and stuff..

Answer 2

I heard only about an American(110V-50Hz) and an European(220V-60Hz) systems....
Plugs are different from USA to Europe, but also in Europe there are differences........for example in UK plugs are different than the rest of Europe, and there are different kinds of plugs (Big, Small, shuko, CEE).
In Asia, Africa, Oceania plugs are different but I think they use 220V-60Hz like in Europe....I think!!

Answer 3

Good question...i'm going to stick around for some answers.

Answer 4

Very early isolated AC generating schemes used arbitrary frequencies based on convenience for steam engine, water turbine and electrical generator design. In the late 19th century, designers would pick a relatively high frequency for systems featuring transformers and arc lights, so as to economize on transformer materials, but would pick a lower frequency for systems with long transmission lines or feeding primarily motor loads or rotary converters for producing direct current. Frequencies between 16 2/3 Hz and 133 1/3 Hz were used on different systems. For example, the city of Coventry, England, in 1895 had a unique 87 Hz single-phase distribution system that was in use until 1906.

Once induction motors became common, it was important to standardize frequency for compatibility with the customer's equipment. Standardizing on one frequency also, later, allowed interconnection of generating plants on a grid for economy and security of operation.

Though many theories exist, and quite a few entertaining urban legends, there is little certitude in the details of the history of 60 Hz vs. 50 Hz. What is known is that Westinghouse in the US decided on 60 Hz and AEG in Germany decided on 50 Hz, eventually leading to the world being mostly divided into two frequency camps. Frequencies much below 50 Hz gave noticeable flicker of arc or incandescent lighting. Westinghouse decided on 60 Hz before 1892 and AEG decided on 50 Hz by 1899. Tesla is believed to have had a key influence in the choice of 60 Hz by Westinghouse. Use of 60 Hz allowed induction motors to operate at the same speeds as standardized steam engines common in the late 19th century.

However, the first generators at the Niagara Falls project, built by Westinghouse, were 25 Hz because the turbine speed had already been selected before alternating current power transmission had been definitively selected.

Westinghouse would have selected a low frequency of 30 Hz to drive motor loads, but the turbines for the project had already been specified at a speed which was incompatible with a generator designed for 30 Hz. Because the Niagara project was so influential on electric power systems design, 25 Hz prevailed as the North American standard for low-frequency AC.

A General Electric study concluded that 40 Hz would have been a good compromise between lighting, motor, and transmission needs. Some 40 Hz systems were built. A large interconnected 40 Hz network existed in north-east England (the Newcastle on Tyne Electric Supply Company, NESCO) until the advent of the National Grid (UK) in the late 1920's, and projects in Italy used 42 Hz. Although frequencies near 40 Hz found some commercial use, this frequency never overcame the "installed base" of 25, 50 and 60 Hz equipment. The oldest continuously-operating commercial hydroelectric power plant in the United States, at Mechanicville, New York, still produces electric power at 40 Hz and supplies power to the local 60 Hz transmission system through frequency changers.

Frequency changers used to convert between 25 Hz and 60 Hz systems were awkward to design; a 60 Hz machine with 24 poles would turn at the same speed as a 25 Hz machine with 10 poles, making the machines large, slow-speed and expensive. A ratio of 60/30 would have simplified these designs, but the installed base at 25 Hz was too large to be economically opposed.

AEG's choice of 50 Hz is thought by some to relate to a more "metric-friendly" number than 60. It may also have been an intentional decision to be incompatible, although since so many frequencies were used it may not have been clear that any one value was desirable. A plethora of frequencies continued in broad use (London in 1918 had 10 different frequencies), and it wasn't until after World War II with the advent of affordable electrical consumer goods that broader standards were enacted.

Other frequencies were somewhat common in the first half of the 20th century, and remain in use in isolated cases today, often tied to the 60 Hz system via a rotary converter or static inverter frequency changer. Because of the cost of conversion, some parts of the distribution system may continue to operate on original frequencies even after a new frequency is chosen. 25 Hz power was used in Ontario, Quebec, the northern USA, and for railway electrification. In the 1950s, many 25 Hz systems, from the generators right through to household appliances, were converted and standardized. Some 25 Hz generators still exist at the Beck 1 and Rankine generating stations near Niagara Falls to provide power for large industrial customers who did not want to replace existing equipment; and some 25 Hz motors exist in New Orleans' floodwater pumps.

In the United States, the Southern California Edison company had standardized on 50 Hz and did not completely change frequency of their generators and customer equipment to 60 Hz until around 1948. Some projects by the Au Sable Electric Company used 30 Hz at transmission voltages up to 110,000 volts in 1914.

Even by the middle of the 20th century, utility frequencies were still not entirely standardized at the now-common 50 Hz or 60 Hz. In 1946, a reference manual for designers of radio equipment listed the following now obsolete frequencies as in use. Many of these regions also had 50 cycle, 60 cycle or direct current supplies.

Frequencies in Use in 1946 (As well as 50 Hz and 60 Hz)

Cycles=Region
25=Canada(Southern Ontario), Panama Canal Zone(*), France, Germany, Sweden, UK, China, Hawaii, India, Manchuria
40=Jamaica, Belgium, Switzerland, UK, Egypt, West Australia(*)
42=Czechoslovakia, Hungary, Italy, Monaco(*), Portugal, Rumania, Yugoslavia, Libya (Tripoli)
43=Argentina
45=Italy, Libya (Tripoli)
76=Gibraltar(*)
100=Malta(*), British East Africa

Where regions are marked (*), this is the only utility frequency shown for that region.


As for the plugs, these are unique to prevent equipment from being connected to the wrong system.