power factor meter

[sasquatch_4]

I printed off a power factor meter circuit from (design notes.com). I have to give a presentation on the details of how each component works. I have basic knowledge of the components, but I don't know enough to say how these components affect each other. If I could divide this circuit into the possible subcircuits and explain how these subcircuits affect each other, then that may give me enough information to speak about it as well. I tried to copy off the circuit from design notes.com, but only the components list copied. Any help would be greatly appreciated. My email is [email protected]


Perry

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Power Factor Meter
Russell Kincaid





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Circuit Description
Power factor is defined as the ratio of true power as measured by a wattmeter to the apparent power as measured by an ammeter and voltmeter. The difference between true and apparent power is a function of the phase angle between voltage and current. When voltage and current are in phase, the true power is equal to apparent power, the power factor is one. When the voltage and current are 90 degrees out of phase, the true power is zero and the power factor is zero. This circuit measures the phase angle between voltage and current. The output is a pulse at the AC frequency whose width is inversely proportional to the power factor. When the pulse width is zero, the power factor is one.

The current and voltage channels are similar: 60Hz bandpass filter, limiter, and comparator. The comparators feed an exclusive-or circuit which produces the output pulse. To determine if the current is leading or lagging, the voltage and current channel outputs are ANDed with the power factor output. There will only be output from the LAG gate when the current is lagging.

The only adjustment is R4 which tunes the bandpass filter, adjusting it's phase to compensate for component tolerances. Adjust R4 such that the power factor output is zero with a resistive power load.

Parts List

Part Reference
Description
Qty Notes
CURRENT TRANSFORMER

1
1000:1

U1
LM324
1


U2
LM393 dual comparator
1


U3
74HC86
1
XOR exclusive-or gate

U4
74HC08
1
AND quad and gate

D1,D2,D3,D4
1N4148
4
small signal diode

C1
0.1uF, 50 V, 1%
4


R1
2.2 meg, 1/8W, 5%
1


R2
2K, 1/8W, 1%
1


R3, R9
330K, 1/8W, 1%
2


R4
500 Ohm pot
1


R5, R6, R10, R11 1K, 1/8W, 5% 4
R7 82K, 1/8W, 5% 1
R8 2.2K, 1/8W, 1% 1






ion to speak about it.

[MP]

Here is the schematic. All you have to do is right click on the picture on their website and choose "Save Picture As".
BTW...they have a pretty good sized website. In the future, you might get better help by posting a link to the article so that someone does not have to search through all of the categories to find it.

MP