原创问题：中美电压差异问题

新用户

我们知道在中国，欧洲以及其他绝大多数国家，民用交流电电压为220伏。www.ddhw.com

 

但是在美国，日本和其他一些少数国家却是110伏！www.ddhw.com

 

请问，为什么？为什么美国不是220？

www.ddhw.com

 

花心石

How values were selected The type of electricity delivered to homes and businesses was first direct current (DC) but then changed to AC electricity. The standard voltage level started at 110V, went to 240V, back to 110V, and then to 220V. The frequency started at 60Hz and then went to 50Hz in most areas.www.ddhw.com Tesla starts AC Early in the history or electricity, Thomas Edison's General Electric company was distributing DC electricity at 110 volts in the United States. Then Nikola Tesla the devised a system of three-phase AC electricity at 240 volts. Three-phase meant that three alternating currents slightly out of phase were combined in order to even out the great variations in voltage occurring in AC electricity. He had calculated that 60 cycles per second or 60Hz was the most effective frequency. Tesla later compromised to reduce the voltage to 110 volts for safety reasons.www.ddhw.com Europe goes to 50Hz With the backing of the Westinghouse Company, Tesla's AC system became the standard in the United States. Meanwhile, the German company AEG started generating electricity and became a virtual monopoly in Europe. They decided to use 50Hz instead of 60Hz to better fit their metric standards, but they kept the voltage at 110V.www.ddhw.com Unfortunately, 50Hz AC has greater losses and is not as efficient as 60HZ. Due to the slower speed 50Hz electrical generators are 20% less effective than 60Hz generators. Electrical transmission at 50Hz is about 10-15% less efficient. 50Hz transformers require larger windings and 50Hz electric motors are less efficient than those meant to run at 60Hz. They are more costly to make to handle the electrical losses and the extra heat generated at the lower frequency.www.ddhw.com Europe goes to 220V Europe stayed at 110V AC until the 1950s, just after World War II. They then switched over to 220V for better efficiency in electrical transmission. Great Britain not only switched to 220V, but they also changed from 60Hz to 50Hz to follow the European lead. Since many people did not yet have electrical appliances in Europe after the war, the change-over was not that expensive for them.www.ddhw.com U.S. stays at 110V, 60Hz The United States also considered converting to 220V for home use but felt it would be too costly, due to all the 110V electrical appliances people had. A compromise was made in the U.S. in that 220V would come into the house where it would be split to 110V to power most appliances. Certain household appliances such as the electric stove and electric clothes dryer would be powered at 220V. When visiting another country Bringing an electrical appliance from one country to another may require some special converters, transformers and adapters to allow the appliance or device to work properly. Converters Converters are typically used to decrease the AC voltage from 220V to the 110V level needed by the appliance.www.ddhw.com They are only used for simple electrical products such as hair dryers, steam irons, shavers, or small fans. They are only used for short periods of time, can only be used for ungrounded appliances, and must be unplugged from the wall when not in use. Converters cannot be used by electronic devices such as radios or computers. A transformer is used for those devices. The reason is that a converter simply cuts the AC sine wave in half, reducing the voltage. Electronic devices need the full sine wave to function properly. Some converters will also change AC to DC. An example is converting 120V AC to 12V DC.www.ddhw.com Transformers Transformers are used to increase or decrease the voltage and should be used with electronic devices such as radios, televisions, computers and other devices having electronics circuitry.www.ddhw.com Transformers are more expensive than converters. They can also be used with electric appliances and may be operated continually for many days. A device like a hair dryer does not have any electronic circuitry. It simply has a heater element and electric fan, so it and can use either a converter or transformer. Dual voltage devices Some devices have a built-in converter or transformer, such that they are called dual voltage devices. Most laptop battery chargers and AC adapters are dual voltage, so they can be used with only a plug adapter for the country you are visiting.www.ddhw.com Plug Adapters Outlet plugs are different in the various countries. Plug adapter must often be used when visiting a different country. These adapters do not convert electricity. Rather, they simply allow a dual voltage appliance, transformer or converter from one country to be plugged into the wall outlet of another country. Frequency difference Converters and transformers only change the voltage and not the frequency. The result is that a motor in a 50Hz appliance will operate slightly faster on 60Hz electricity. Likewise, a clock made for 60Hz will run slower in a country using the 50Hz frequency.www.ddhw.com Most modern electronic equipment like computers, printers, DVD players and stereos are usually not affected by the frequency difference. Country listing Of the over 200 countries listed below, less than 40 use 110V. Some countries use dual voltages. 43 countries use 60Hz, while the rest use 50Hz.www.ddhw.com Country Voltage Frequency Afghanistan 220V 50Hz Albania 230V 50Hz Algeria 230V 50Hz American Samoa 120V 60Hz Andorra 230V 50Hz Angola 220V 50Hz Anguilla 110V 60Hz Antigua 230V 60Hz Argentina 220V 50Hz Armenia 230V 50Hz Aruba 127V 60Hz Australia 240V 50Hz Austria 230V 50Hz Azerbaijan 220V 50Hz Azores 230V 50Hz Bahamas 120V 60Hz Bahrain 230V 50Hz Balearic Islands 230V 50Hz Bangladesh 220V 50Hz Barbados 115V 50Hz Belarus 230V 50Hz Belgium 230V 50Hz Belize 110/220V 60Hz Benin 220V 50Hz Bermuda 120V 60Hz Bhutan 230V 50Hz Bolivia 230V 50Hz Bosnia 230V 50Hz Botswana 230V 50Hz Brazil 110-220V 60Hz Brunei 240V 50Hz Bulgaria 230V 50Hz Burkina Faso 220V 50Hz Burundi 220V 50Hz Cambodia 230V 50Hz Cameroon 220V 50Hz Canada 120V 60Hz Canary Islands 230V 50Hz Cape Verde 230V 50Hz Cayman Islands 120V 60Hz Central Africa 220V 50Hz Chad 220V 50Hz Channel Islands 230V 50Hz Chile 220V 50Hz China 220V 50Hz Colombia 110V 60Hz Comoros 220V 50Hz Congo (Zaire) 220V 50Hz Cook Islands 240V 50Hz Costa Rica 120V 60Hz Côte d'Ivoire (Ivory Coast) 220V 50Hz Croatia 230V 50Hz Cuba 110/220V 60Hz Cyprus 230V 50Hz Czech Republic 230V 50Hz Denmark 230V 50Hz Djibouti 220V 50Hz Dominica 230V 50Hz Dominican Republic 110V 60Hz East Timor 220V 50Hz Ecuador 127V 60Hz Egypt 220V 50Hz El Salvador 115V 60Hz Equatorial Guinea 220V 50Hz Eritrea 230V 50Hz Estonia 230V 50Hz Ethiopia 220V 50Hz Faeroe Islands 230V 50Hz Falkland Islands 240V 50Hz Fiji 240V 50Hz Finland 230V 50Hz France 230V 50Hz French Guyana 220V 50Hz Gaza 230V 50Hz Gabon 220V 50Hz Gambia 230V 50Hz Germany 230V 50Hz Ghana 230V 50Hz Gibraltar 230V 50Hz Greece 230V 50Hz Greenland 230V 50Hz Grenada 230V 50Hz Guadeloupe 230V 50Hz Guam 110V 60Hz Guatemala 120V 60Hz Guinea 220V 50Hz Guinea-Bissau 220V 50Hz Guyana 240V 60Hz Haiti 110V 60Hz Honduras 110V 60Hz Hong Kong 220V 50Hz Hungary 230V 50Hz Iceland 230V 50Hz India 240V 50Hz Indonesia 230V 50Hz Iran 230V 50Hz Iraq 230V 50Hz Ireland (Eire) 230V 50Hz Isle of Man 230V 50Hz Israel 230V 50Hz Italy 230V 50Hz Jamaica 110V 50Hz Japan 100V 50/60Hz Jordan 230V 50Hz Kenya 240V 50Hz Kazakhstan 220V 50Hz   Country Voltage Frequency. Kiribati 240V 50Hz Korea, South 220V 60Hz Kuwait 240V 50Hz Kyrgyzstan 220V 50Hz Laos 230V 50Hz Latvia 230V 50Hz Lebanon 230V 50Hz Lesotho 220V 50Hz Liberia 120V 60Hz Libya 127/230V 50Hz Lithuania 230V 50Hz Liechtenstein 230V 50Hz Luxembourg 230V 50Hz Macau 220V 50Hz Macedonia 230V 50Hz Madagascar 127/220V 50Hz Madeira 230V 50Hz Malawi 230V 50Hz Malaysia 240V 50Hz Maldives 230V 50Hz Mali 220V 50Hz Malta 230V 50Hz Martinique 220V 50Hz Mauritania 220V 50Hz Mauritius 230V 50Hz Mexico 127V 60Hz Micronesia 120V 60Hz Moldova 230V 50Hz Monaco 230V 50Hz Mongolia 230V 50Hz Montserrat Islands 230V 60Hz Morocco 220V 50Hz Mozambique 220V 50Hz Myanmar (Burma) 230V 50Hz Namibia 220V 50Hz Nauru 240V 50Hz Nepal 230V 50Hz Netherlands 230V 50Hz Netherlands Antilles 127/220V 50Hz New Caledonia 220V 50Hz New Zealand 230V 50Hz Nicaragua 120V 60Hz Niger 220V 50Hz Nigeria 240V 50Hz Norway 230V 50Hz Okinawa 100V 60Hz Oman 240V 50Hz Pakistan 230V 50Hz Palmyra Atoll 120V 60Hz Panama 110V 60Hz Papua New Guinea 240V 50Hz Paraguay 220V 50Hz Peru 220V 60Hz Philippines 220V 60Hz Poland 230V 50Hz Portugal 230V 50Hz Puerto Rico 120V 60Hz Qatar 240V 50Hz Réunion Island 230V 50Hz Romania 230V 50Hz Russian Federation 230V 50Hz Rwanda 230V 50Hz St. Kitts & Nevis Islands 230V 60Hz St. Lucia Island 240V 50Hz St. Vincent Island 230V 50Hz Saudi Arabia 127/220V 60Hz Senegal 230V 50Hz Serbia & Montenegro 230V 50Hz Seychelles 240V 50Hz Sierra Leone 230V 50Hz Singapore 230V 50Hz Slovakia 230V 50Hz Slovenia 230V 50Hz Somalia 220V 50Hz South Africa 230V 50Hz Spain 230V 50Hz Sri Lanka 230V 50Hz Sudan 230V 50Hz Suriname 127V 60Hz Swaziland 230V 50Hz Sweden 230V 50Hz Switzerland 230V 50Hz Syria 220V 50Hz Tahiti 110/220V 60Hz Tajikistan 220V 50Hz Taiwan 110V 60Hz Tanzania 230V 50Hz Thailand 220V 50Hz Togo 220V 50Hz Tonga 240V 50Hz Trinidad & Tobago 115V 60Hz Tunisia 230V 50Hz Turkey 230V 50Hz Turkmenistan 220V 50Hz Uganda 240V 50Hz Ukraine 230V 50Hz United Arab Emirates 220V 50Hz United Kingdom 230V 50Hz United States 110/220V 60Hz Uruguay 220V 50Hz Uzbekistan 220V 50Hz Venezuela 120V 60Hz Vietnam 220V 50Hz Virgin Islands 110V 60Hz Western Samoa 230V 50Hz Yemen 230V 50Hz Zambia 230V 50Hz Zimbabwe 220V 50Hz Exceptions Some countries can't decide on a standard. Brazil In Brazil, most states use between 110V and 127V AC electricity. But many hotels use 220V. In the capital Brasilia and in the northeast of the country, they mainly use 220-240V. Japan In Japan, they use the same voltage everywhere, but the frequency differs from region to region. Eastern Japan, which includes Tokyo, uses 50Hz. In western Japan, which includes Osaka and Kyoto, they use 60 Hz.www.ddhw.com The reason for this is that after World War II, Britain was in charge of helping reconstruct Japan's electrical system in the easter part of the country and the United States set up the electricity in the western part of Japan. Since Great Britain (United Kingdom) had been using 60Hz before the war and had just switched over to the European 240V 50Hz, it is strange that they set up Japan at 100V and 50Hz, especially when the U.S. was using 60Hz. www.ddhw.com Having different voltages and frequencies within the country not only must be confusing for the people but also can result in extra costs for appliances and adapters. In conclusion The voltage and frequency of AC electricity varies from country to country throughout the world. Most use 220V and 50Hz. About 20% of the countries use 110V and/or 60Hz to power their homes. 220V and 60Hz are the most efficient values, but only a few countries use that combination. The United States uses 110V and 60Hz AC electricity.www.ddhw.com from: http://www.school-for-champions.com/science/ac_world_volt_freq.htm#listing   www.ddhw.org---

花心石

Why does Australia have a 240-volt electricity supply when the United States has 110 volt? Houses in the US get 240V from the street to the house meter box, which then dropsto 120V for distribution to house wall outlets. Historically, Edison decided on 110V because that's the voltage his light bulbs worked on. We learnt from America's mistakes and use 240V in Australia because less energy is lost as heat in cables behind the walls. Russell Wild, Kincumberwww.ddhw.com The lower voltage in the US has human safety as a main reason. In some third-world countries, it can be as high as 440, which is fatal if touched. Dr. J.N. Parikh, Sydney Only an American could ask this. Almost all of the world is 240 volts and 50 cycles electricity. It's the USA, and I think Japan, who have 110 volts and 60 cycles. Just like mobile phones work anywhere in the world except the USA unless one has the latest model. George Everson, Crestwood We have an electrifiying currency here in Australia; in the USA, their one is shocking!  Steve Barrett, Glenbrookwww.ddhw.com AC (alternating current) electricity voltage varies throughout the world. Under the guidance of Nikola Tesla, the discoverer of alternating-current power transmission, the US began in the late 1800s using 240 volts but later reduced it to 110V for safety reasons. Europe stayed at 110V AC until the 1950s when they switched over, as did Australia and much of the world, to 220-240V for more efficient electrical transmission. The US also considered converting to 220-240V for home use but decided it would be too costly, due to all the 110V electrical appliances people had.  John Moir, Mollymookwww.ddhw.com  The 110 volts used in USA & Canada is for most domestic appliances . Domestic stoves, however are sometimes are 220 volts and some commercial buildings have 300 volts or other irregular voltages for lighting. Our system is consistent for most applications, and is similar to most of the world (e.g. Europe) where 220 or 230 volts is used. Our appliances will run on these voltages, and our own supply is now 230 volts, I believe, Greg Lilly, NSW   www.ddhw.org---

花心石

http://www.voltageconverters.com/voltageguide.htm www.ddhw.com   www.ddhw.org---

husonghu

  好象for safety reasons是对的. 谢谢花心石MM的礼品

220V我不怕

请先弄明白一件事,是电压高对人危险,还是电流大对人危险,或以数据为准:交流220V电你一下,和交流20A电你一下,你知道结果是什么?

新用户

我认为电压高对人体危害大，严格的说来应该是电势差（=电压）大，对人体更有害。   人体的电阻是固定的，电势差大，就可以在人体造成较大的电流从而使人体受损。所以我认为判定安全性，电压是唯一的指标。   你说交流20A，指的是在人体中产生20A的电流吗？如果是，那么就一定需要一定数量的电压。用36V的电压，在人体中产生20A的电流是不可能的！ www.ddhw.com 原贴： 文章来源: 220V我不怕 于 2006-11-16 19:24:15 标题：回复：原创问题：中美电压差异问题 请先弄明白一件事,是电压高对人危险,还是电流大对人危险,或以数据为准:交流220V电你一下,和交流20A电你一下,你知道结果是什么?   www.ddhw.com

新用户

其实，我并不确信正确的答案应该是什么。但是我发现我的理解跟花心石MM给出的解答一致。   我认为： 传输过程中，电压越高，损耗就越小。（记得中学学过这个）。尽管多数情况下都是高压传输（成千上万伏），但是在居民区传输应该是一般的民用电压。所以，从这点考虑，220V比较合理。   但是从安全性的角度考虑110V好更好一些。110V远远的大于安全电压36V，但是却比220V安全很多。老美应该比较重视安全。所以他们更愿意使用110。 www.ddhw.com

220V我不怕

这么说吧,让你接上衡压220V电源和让你接上衡流20A电源.

新用户

让人接上衡压220V电源，一般情况下，会被电击死亡。www.ddhw.com 人体的电阻一般在10,000~100,000欧姆之间，那么如果使用220V. 就会产生0.022~0.0022 A的电流。 也就是说人体中如果产生0.022A的电流就可以至人死亡。（当然其中的过程比较复杂） 所以，20A当然一定会让人死亡。 但是，如何才能在人体产生20A 电流呢？这需要 20x10000=200,000 V得电压。 所以，当你让我比较220V电压与20A电流的时候，你其实在让我比较 220V 与 200,000V 的差别。   原贴： 文章来源: 220V我不怕 于 2006-11-17 15:15:27 标题：回复：我认为你的这个问题有问题 这么说吧,让你接上衡压220V电源和让你接上衡流20A电源. www.ddhw.com

我也不怕220V

你知道什么是恒流源?

哈和哈

你以为恒压源接哪,哪就是恒压?别搞哭了 www.ddhw.com

220V怕我也

谁说美国不用220V? 你们家的电炉(电热丝),烘干机(电热丝),电暖气(电热丝)就是220. 工厂里就更多了,马达以220V,370V为多,加热器220V占多数,大楼外的大汞灯,----- 总之,凡是功率过1000瓦的,大多需要220V.理由不需要多说了,已有人答了. 经常看到求助广告:因带来了大陆的什么什么电器产品,需要110V转换到220V的变压器. 经有关人士的帮助,从求助者的家里直接接出了220V,而且功率上3000瓦一点没问题. www.ddhw.com