why electrical apllainces like TV FRIDGE work on AC current not DC current?

Question

why electrical apllainces like TV FRIDGE work on AC current not DC current?

Answer 1

The main reason is that the generation and distribution of AC is much easier / cheaper.



Electricity is distributed over long distances at a high voltage (to reduce losses in the transmission lines), and reduced to the normal household voltage using a transformer which will only work on AC.

Answer 2

It was decided many years ago (after a lot of argument) to distribute electricity as AC not DC. The reason was that if you want to send electricity a long distance, it's best to do it at high voltage and low current than low voltage and high current. High currents need thick cables, and copper is expensive.



OK, so if you are using high voltage transmission (many thousands of volts) you can't have that going into peoples' houses, you have to step down the voltage to a safer level for domestic and industrial use. To do that with DC is rather difficult; to do it with AC is very easy - you just need some coils of wire wrapped around a big lump of iron, otherwise known as a transformer.

Using AC also makes it easy to step down the voltage even further inside the appliance, you just use another transformer.

Answer 3

Because AC is what is available in your house, not DC.



Yes, you could build a fridge or TV that worked on DC, but where would you plug it in? (Although they do make appliances for 12 VDC, for trailers)





OR, are you asking why they don't work on both AC and DC?



because inside the appliance there are motors and transformers that work only on AC and not DC.



Yes, you could design an appliance that would work on 120 VAC and 120 VDC, either one, but it would add to the price, and The DC part would be useless, because, again, where would you plug it in.







OR, are you asking why AC power is distributed instead of DC power? The others have answered this possibility.



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Answer 4

AC power is able to be distributed from the generating station to you home will much less loss than DC power. AC voltage is easily stepped up and down in voltage through the use of transformers. The same amount of power can be sent across a wire at a very high voltage and lower current. Power losses are based upon the square of the currnt time the resistance. So if you double the voltage the current flow is cut in half to send the same amount of power (P = ExI) you then cut your power (P = IxIxR) losses by a factor of four.



As far as the power company is concerned then want to distriute power to home with as little waste (loss) as possible.



DC for electronics is provided by AC to DC power supplies or batteries.



There have been some attempt to establish a multi power standard for home wiring. But these have never taken off. mainly this is due to the expense of wiring a home with additional wiring. You also have the chicken and teh egg syndrome where you have a home wired with DC power as well but no devices that are wired to interface with it. Also many electronics use several different voltage levels (3,5,6,9,12,15,18,24 volts and positive and negative versions of these voltages)



Besides the economic factor of an additional distribution system or home wiring you have technical limitations placed on electronics design to use a standard DC voltage level. So it has been up to the electronics manufacturers to design the DC power adapters to provide what ever DC voltage their device needs.





AC powered homes also stand in teh way of home photovoltaic systems. Part of the large cost in a Solar PV system for home use is converting energy stored in batteries (DC) and converting by an inverter into clean AC for home use. It is cheaper and more efficient to use Solar generated DC directly for devices which do not require AC.



Solar PV lighting using DC power lights or using the DC power to charge batteries for an electric vehicle.



So consideration is now being given to wiring homes with a seperate DC wiring system for low voltage DC interior lighting to augment traditional AC lighting.



No of this stuff is impossible the stumbling block is cost. The economics of Solar power compared to low cost traditional power sources make for very long payback times. No one want to spend 30K on a system that will take decades to pay for itself in a home environment (not counting maintenance and repair costs either).

Answer 5

The answers that it is more efficient to transmit high voltage a.c. and to step it down at the load end are correct. Other considerations are that most d.c. motors require a commutator and brush rigging which require frequent maintenance and would penetrate hermetic seals such as are used in air conditioner and refrigerator compressors.