WEBVTT

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Diagram: Measurement of active and apparent power (wattmeter, ammeter and voltmeter)

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The wattmeter displays milli-Watt: so here 1880 mW

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The red ammeter (230 mA) in series, the yellow voltmeter in parallel on the coil

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The product U * I = 20 * 0.23 A = 4.6 "Watt", for only 1.9 Watt displayed!

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The product voltage * intensity is the apparent power supplied by the generator in VA!

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The Wattmeter displays the power actually converted (here mechanical to paste relay)

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The contact requires 1.9 W to stick but the coil absorbs 4.6 VA!

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The 'sources': inverters, transformers ... Indicates power in VA Volt * Ampere

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A 2 VA transformer would be insufficient! At least 4.6 VA to provide 2 W!

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1.9 / 4.6 (P in W / S in VA) = Cosine phi: cos phi = about 0.3 to 0.4 here

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EN green my capacitance which displays 33 μF for capacitors in blue disks.

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We will connect the 33 μF in parallel on the coil (at the level of the voltmeter) and observe I

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Apparent power bore its name badly: the generator supplies it, the wires transport it

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I carry out the paralleling in the level of the voltmeter, more practical and identical

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The intensity I is divided by 3! 76 mA against 230! S = 0.076 * 20.5 V = 1.5 VA approximately

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Now, with inaccuracies, P in Watt = S in VA! The decrease of P is an imprecision

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Here P drop, a little before in fact

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S in VA = P in Watt! So the cosine, cos phi = 1!

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It is now provided that the actually converted hence the name "power factor"

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For the cos phi, review video (same editing) with the oscilloscope as needed

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The electric efficiency is close to 1 when cos phi = 1 (remains the losses iron, Joule ...)

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Now you do not need to oversize the generator, cables and protections by a factor of 3!

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S is supplied by the generator, carried by the cables and absorbed by the receiver

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With S it produces Q its reagent: magnetic field that can be compensated

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It is indispensable, it can not be suppressed: it is compensated. It is he who produces the force

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The capacitors will produce the reagent useful to the coil for its magnetic field

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Spend everything in kW, Imagine: between a transformer 2 kVA (cos phi 1) and one of 5 kVA ...

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The difference in price, mass, space ...

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With Pythagoras one can easily find reactive power