Solar Flare wrote:

Capacitive reactance is lower to higher frequencies...

How does that work? I thought they could only reduce IV phase angles.

Power Factor correction capacitors can help absorb some of the harmonics.

Interesting. I wonder how to calculate the power factor improvement for,
say, a 4.7 uF cap in parallel with a 150 watt 277 V load with a 10% 3rd
harmonic distortion.

The first step might be to calculate the original power factor, with no cap.

This seems different and more promising:

https://www.galco.com/circuit/PFCC_har.htm

Harmonic currents can be significantly reduced in an electrical system
by using a harmonic filter.

In its basic form, a filter consists of a capacitor connected in series
with a reactor tuned to a specific harmonic frequency. In theory,
the impedance of the filter is zero at the tuning frequency; therefore,
the harmonic current is absorbed by the filter. This, together with
the natural resistance of the circuit, means that only a small level
of harmonic current will flow in the network.

A 600 Hz filter might help a power supply that clips 10% of an 60 Hz peak.

Nick

Notch filters are always good selective units. Our problem is
filtering 10MW ++ loads full of harmonics. That is a lot of heat to
disapate. hmmmmmm... building heat in the winter and hot water? Why
bother when tons of heat is thrown away in the main transformers via
cooling fans and pumps. Trouble is the utility buldings run metered in
with the big bulk of the consumers and is not apparent to anybody in
the utility. **SIGH**

wrote in message
...
Solar Flare wrote:

Capacitive reactance is lower to higher frequencies...

How does that work? I thought they could only reduce IV phase
angles.

Power Factor correction capacitors can help absorb some of the
harmonics.

Interesting. I wonder how to calculate the power factor improvement
for,
say, a 4.7 uF cap in parallel with a 150 watt 277 V load with a 10%
3rd
harmonic distortion.

The first step might be to calculate the original power factor, with
no cap.

This seems different and more promising:

https://www.galco.com/circuit/PFCC_har.htm

Harmonic currents can be significantly reduced in an electrical
system
by using a harmonic filter.

In its basic form, a filter consists of a capacitor connected in
series
with a reactor tuned to a specific harmonic frequency. In theory,
the impedance of the filter is zero at the tuning frequency;
therefore,
the harmonic current is absorbed by the filter. This, together with
the natural resistance of the circuit, means that only a small
level
of harmonic current will flow in the network.

A 600 Hz filter might help a power supply that clips 10% of an 60 Hz
peak.

Nick

Solar Flare wrote:

Notch filters are always good selective units...

The R in these series RLC circuts broadens the notch and uses real power.
How much would a 4.7 uF cap in parallel with a 150 watt 277 V load
with a 10% 3rd harmonic distortion raise the power factor?

With 1/(377C) = 564 ohms at 60 Hz and 277 V and L = 1/((2Pi180)^2x4.7x10^-6)
= 0.166 henrys in series to resonate at 180 Hz, limiting 60 Hz ripple current
requires Z = sqr(R^2+(wL-1/(wC)^2) = 564, ie R^2+(377x0.166-564)^2 = 564^2,
ie R = sqr(564^2-251291) = 258 ohms. With how many real watts?

How much would that raise the power factor?

Nick

Man, you're pushing my math skills here. I used to gobble this stuff
for breakfast nut now I'm not even sure I could do it with a Geritol
injection...LOL

wrote in message
...
Solar Flare wrote:

Notch filters are always good selective units...

The R in these series RLC circuts broadens the notch and uses real
power.
How much would a 4.7 uF cap in parallel with a 150 watt 277 V load
with a 10% 3rd harmonic distortion raise the power factor?

With 1/(377C) = 564 ohms at 60 Hz and 277 V and L =
1/((2Pi180)^2x4.7x10^-6)
= 0.166 henrys in series to resonate at 180 Hz, limiting 60 Hz
ripple current
requires Z = sqr(R^2+(wL-1/(wC)^2) = 564, ie R^2+(377x0.166-564)^2 =
564^2,
ie R = sqr(564^2-251291) = 258 ohms. With how many real watts?

How much would that raise the power factor?

Nick