VOLTAGE CONVERTERS
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VOLTAGE CONVERSION GUIDE
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History of Worldwide Electric Voltage and Frequency
The voltage and frequency of alternating current (AC) electricity used around the world can vary from country to country. The two main voltages used are either 110V AC or 220V AC. The 110V and 220V voltages are average values, as the voltages can fluctuate during usage. Most countries use a frequency of 50Hz (or 50 cycles per second) for their AC. Some countries use 60Hz. The US uses 110V 60 Hz AC electricity.
How Voltage and Frequency were Selected
The first type of electricity delivered to homes and businesses was direct current (DC), but it was then changed to AC electricity. The standard voltage level was originally 110V, went to 220V, back to 110V and then to 220V. The frequency of the AC power supply was originally 60Hz and then was changed to 50Hz in most areas.
Tesla Starts AC
In the early days of electricity, Thomas Edison's General Electric company was distributing 110V DC electricity in the US. Nikola Tesla then devised a system of distributing electricity using three-phase 240V AC. The three-phase meant that three, slightly out of phase, alternating currents were combined in order to even out the variations in voltage occurring in AC electricity. Tesla had calculated that 60Hz was the most effective frequency for distributing electricity. He later compromised and reduced the voltage to 110V for safety reasons.
Europe goes to 50Hz
With the help of the Westinghouse Company, Tesla's AC system became the standard in the US. In the meantime, 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.
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.
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.
US stays at 110V 60Hz
The US 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 US 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
Travelling with 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.
Voltage Converters
Voltage converters are used to change the AC voltage needed the appliance. They can either decrease the AC voltage from 220V to 110V (step-down converter) or increase the voltage from 110V to 220V (step-up converter).
Voltage converters can be used for simple electrical products such as irons, hair dryers or shavers. They can only be used for a short period of time, on ungrounded devices and must be unplugged from the wall when not being used.
Voltage converters cannot be used by electronic devices such as radios or computers. A transformer is needed for those devices because a converter simply cuts the AC sine wave in half, reducing the voltage. Electronic devices need the full sine wave to work correctly.
Some converters will also change AC to DC, for example converting 120V AC to 12V DC.
Voltage Transformers
Voltage transformers are used to increase or decrease the voltage and can be used with electronic devices such as radios, televisions, computers and other devices having electronics circuitry.
Voltage transformers are more expensive than voltage 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
Dual voltage devices have a built-in converter or transformer. 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.
Plug Adapters
Outlet plugs can be different in different countries. A plug adapter must often be used when visiting a different country. These adapters do not convert electricity, but simply allow a dual voltage appliance, transformer or converter from one country to be plugged into the wall outlet of another country.
Frequency Differences
Voltage converters and transformers only change the voltage and do not change 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.
Most modern electronic equipment like computers, printers, DVD players and stereos are usually not affected by the frequency difference.
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