December 17, 2009
NIST Team Demystifies Utility Of Power Factor Correction Devices
If you've seen an Internet ad for capacitor-type power factor correction devices, you might be led to believe that using one can save you money on your residential electricity bill. However, a team including specialists at the National Institute of Standards and Technology (NIST) have recently explained* why the devices actually provide no savings by discussing the underlying physics.
The devices"”sometimes referred to as Amp Reduction Units or KVARs**"”are touted as good investments because they reduce the amount of current drawn from power lines while simultaneously providing the necessary amount of current to appliances inside the house. Though engineers elsewhere have discredited the devices for use in typical residences already, NIST physicist Martin Misakian and two of his colleagues decided to write a brief primer describing the devices' inner workings for readers who are not power engineers, but who still have some technical background.
Power factor correction devices have some use, though. The authors point out that while they will not reduce the average homeowner's bill, they may benefit the environment. When electricity travels from a local transformer to a residence, some power is lost due to electrical resistance. But because a utility would need to supply less current to a residence that employs a power factor correction device, these losses would decrease"”thus potentially reducing the amount of greenhouse gases a fossil fuel-burning utility would emit. But while the primer does provide a rough calculation of a utility's savings by considering the operation of a residential air conditioner, Misakian says readers must investigate the details of these options for themselves.
"If homeowners wanted to help reduce the amount of carbon dioxide produced, they could install a device," Misakian says, "but they would also have to consider the greenhouse gases generated during the fabrication of the device itself."
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