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Unformatted text preview: Boise State University Department of Electrical and Computer Engineering ECE 212L – Circuit Analysis and Design Lab Experiment #4: Power Factor Correction 1 Objectives The objectives of this laboratory experiment are: • to calculate and measure complex power, observe lagging power factor, and correct lagging power factor by adding capacitive compensation. 2 Theory The apparent power or voltamperes (VA) in a given circuit is the product of the rms voltage and rms current magnitudes. The real power (also referred to as average power or active power) is the apparent power times the cosine of the angle between the voltage and the current waveforms or phasors. This cosine term is known as the power factor, and it is desirable to operate at or near unity power factor. This is the case since equipment costs are largely proportional to conductor size and insulation, which are determined by the voltamperes required. Also, low power factor operation implies high current with resulting small useful work. This is clear since a purely inductive load may draw a large current and thus large voltamperes demand. The real power lost in the transmission or distribution line feeding this load could be substantial. These | ˜ I | 2 R losses are costly to utilities and large energy consumers. It is common to add capacitive reactance to an inductive circuit in order to bring the voltage and current in phase (and thus bring the power factor to unity). This practice is known as power factor correction. Clearly, power factor correction can reduce the cost of electric power system operation and can permit generators to produce more active power at rated kVA. In order to maintain a higher voltage at the load, and reduce line losses, the correction should always be made at the load rather than the source....
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This document was uploaded on 11/01/2011 for the course ECE 212 at Boise State.
- Fall '08