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Electronic Theory and Principle Discussion of electrical theory, law, etc.

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Old 03-13-2018
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ashiekh ashiekh is offline
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What current profile gives the best Power Correction Factor (the least losses)?

A sine wave in-sync with the voltage?

Last edited by ashiekh; 03-13-2018 at 06:38 PM.
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Old 03-14-2018
ridgid13579 ridgid13579 is offline
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Quote:
Originally Posted by ashiekh View Post
What current profile gives the best Power Correction Factor (the least losses)?

A sine wave in-sync with the voltage?
Yes, when the current is in phase with the voltage, you will have a power factor of 1, which is the most ideal.

A resistive load (say a good old wire heater) should have a power factor of 1.
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Old 03-14-2018
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I tried a few current shapes, and so far none have beat the sine wave for losses. I even think I now have a proof of why the current needs to follow the voltage (for minimum losses), that works for all voltage shapes (not just sinusoidal); using ideas from functional analysis.

A strange exception to a resistive load being ideal:
Imagine a bulb whose filament resistance increases with temperature, it is pure resistive, but has higher resistance at high voltages, and so will have a non-sinusoidal current curve and so higher cable loses than an equal load with constant resistance.

Interestingly, the larger the primary capacitors, the worse the power factor issue (assuming no correction), due to reduced conduction angle; by the same reasoning the smaller the load the worse the power factor issue.
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File Type: gif conduction_angle[1].gif (6.0 KB, 5 views)

Last edited by ashiekh; 03-14-2018 at 08:05 PM.
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Old 07-11-2018
gdjacobs gdjacobs is offline
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Well, P = I dot V. If the objective is to minimize I while P and V are constant, obviously the phase between any components should be zero. Also, any harmonics from a non sinusoidal current waveform will be orthogonal to a sinusoidal voltage waveform and will have no contribution to the overall power output and be waste as well.

P = sum ( I_i V_j )
= sum ( |I_i| |V_j| int sin w_i t sin w_j t dt )
= |I_i||V_i| int sin w_i t sin w_i t dt
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Old 07-11-2018
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Nicely argued

Last edited by ashiekh; 07-11-2018 at 08:20 PM.
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