Converter or Transformer? Converters and transformers are electric conversion products that enable safe operation of electric devices in foreign countries. Electric devices that are designed for use with 110V systems require foreign 220V current to be "stepped-down." Devices that are designed for use with 220V systems require foreign 110V current to be "stepped-up." The choice between a converter or a transformer depends on several things.
First, is your device an electric appliance with a high power heating element or mechanical motor such as a hair dryer or iron? If you are using an electric appliance, you need a converter. Or is your device electronic, using electronic chips or circuits, such as a computer, printer or VCR? If you are using an electronic device, you need a transformer. When in doubt about the type of device, use a transformer. Both electric appliances and electronic devices work with a transformer, but only electric appliances work with a converter.
Second, is your use continuous and long-term or is it sporadic and short term? Transformers are designed for long term, continuous use. Converters are designed to operate for only an hour or two at a time.
What's the difference between a converter and a transformer? It lies in how the device converts voltage current. AC power is supplied in alternating bursts that are in a shape called a "sine wave." To reduce 220V to 110V, for example, a converter chops off the sine waves in half whereas a transformer alters the length of the sine waves. This is a critical difference because electronic devices require a full sine wave for operation thus can operate only with a transformer. Electric appliances function with either a full or a half sine wave so can be operated with either a converter or a transformer.
The converter's short-term use and "chopping" off of sine waves are relatively simple and compact functions. The transformer's continuous use and alteration of sine waves are relatively sophisticated functions and require more space. As a result, transformers are generally larger, heavier and much more expensive than converters. Thus if you are going to travel with an electronic device you should purchase one that is dual voltage if it is available.
Most converters and transformers that are available to the consumer do not alter or convert the "cycles," shown as "Hz" on most devices. Although cycle differences may not cause a problem with many devices, they do with some. See our Cycles / Hz Tech Note for further explanation.
It turns out that these transformers consume power whenever they are plugged into the wall, whether they are connected to a device or not. They also waste power when powering a device.
If you have ever felt one and it was warm, that is wasted energy turned to heat. The power consumption is not large -- on the order of 1 to 5 watts per transformer. But it does add up. Let's say that you have 10 of them, and they consume 5 watts each. That means that 50 watts are being wasted constantly. If a kilowatt-hour costs a dime in your area, that means you are spending a dime every 20 hours. That's about $44 every year down the drain. Or, think of it this way -- there are roughly 100 million households in the United States. If each household wastes 50 watts on these transformers, that's a total of 5 billion watts. As a nation, that's half a million dollars wasted every hour, or $4,380,000,000 wasted every year! Think of what you could do with 4 billion dollars…
Where these small loads really take a toll is in remote locations powered by things like solar cells and wind generators. In these systems, you are paying something on the order of $10 to $20 per watt (once you add up the cost of the solar cells, the batteries to store the power, the power regulators and inverter, etc.). Fifty watts at $20 per watt means that you have to spend an additional $1,000 just to power the transformers. In these kinds of systems, small loads are something you avoid by unplugging the transformers when not in use or by eliminating the transformer and powering the device straight from the battery bank to improve efficiency.
However, the added electricity expense is offset by the manufacturing cost savings passed along to the customer, hopefully, as a lower product selling price. For example, it costs a manufacturer considerably less to manufacture and stock one universal "flavor" of printer that runs on 12 volts DC. The manufacturer then packages the printer with a country-dependent voltage AC wall transformer for the country it's being sold in. When a new version of the device comes out, the manufacturer doesn't need to retool the power supply.
For more information on transformers and saving energy, check out the links on the next page.
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