AC and DC electric arc furnaces are used for heating metals and getting them ready for the manufacturing process. These furnaces vary in their energy transfer, though, and the use of DC electric arc furnaces is usually more popular. Understanding the benefit of each can help you determine which furnace is best for your project.
Identification
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AC and DC electric arc furnaces are mechanisms used to heat steel and other metals. The metal goes into the furnace and an electrode heats the device. An AC arc furnace makes use of three electrodes that distribute energy, while a DC arc furnace only has one electrode. These furnaces range in capacity from one ton to 400 tons and can be found in research labs or steel mills.
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AC Arc Furnaces
AC arc furnaces are the older of the two styles, and they've been proven to work well. One advantage to the AC arc furnace is that is has three electrodes that produce heat. If one fails, you can replace or fix one without worrying that the entire system will fail. This can save time and expense. Also, AC arc furnaces cost less than DC furnaces.
DC Arc Furnaces
Because they only have one electrode, DC furnaces take up less space and require less work and maintenance. Also, the less workers have to manage the heaters, the less of a chance of injury. DC furnaces are more expensive to purchase. For instance, an AC furnace will be about $3,000,000 cheaper than a DC furnace, but the DC furnace saves money in the long run. Unlike AC furnaces, it doesn't require burners, which cost about $500,000 each, and the overall energy consumption is less, so utility costs are lower. A DC furnace will make up for its extra upfront costs after about six months of use. A DC furnace uses 50 to 60 percent less energy, and also heats evenly, while AC arc furnaces don't distribute heat as well. The electrode at the bottom of the DC furnace as well as the top allows heat to distribute more evenly.
Considerations
Some steel plants have converted old AC arc furnaces to DC arc furnaces and have seen their overall energy consumption drop considerably.