dlosborne
New Head-Fier
- Joined
- Mar 29, 2008
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Fluorescent lighting and switch-mode power supplies are non-linear loads that are extremely good at generation third order harmonics (i.e., 180Hz for the bulk of North America). The 'energy efficient' fluorescent jobs can be particularly nasty and product third order harmonic currents in excess of 85% of the fundamental current load. Switch-mode power supplies (that massive Antec in the back of your super-demon, space-warping computer or that dirt-cheap flat screen tely, for example) are not much better with 80%+ of the fundamental in harmonic current.
Third order harmonics are know also as zero sequence. (PM me if you would like a deeper explanation of sequential components in multi-phase power systems and I will put you to sleep faster than a six-pack alone at home in front of Knight Rider re-runs). Just know that zero sequence currents flow through neutral conducts and are additive. If you light your house with fluorescents, have a small den of computers or other non-linear loads, and create a parallel path for neutral currents through your amps, you will hear it.
Also, since these AC currents create their own 180Hz alternating magnetic field, nearby conductors can also have harmonic voltages induced; a single winding transformer for your listening pleasure when applied to close to audio gear!
Now, you want to get rid of these harmonic currents in your audio equipment? Do not create parallel paths for neutral currents (power strips can be your friend, Mate) or paths for neutral-to-ground currents.
Yes, the neutral service conductor running to your house is grounded at your service panel. Zero sequence current can flow through the neutral into your gear, through that neutral-to-equipment ground connection the new DIYer soldered/bolted together, through ground to the service entrance neutral, and right back to that big green padmounted transformer out side humming away at a nice fundamental 60Hz.
-electrically isolate your gear
-create distance between nasty carriers of harmonic current (stand-off is security)
Best of luck!
Third order harmonics are know also as zero sequence. (PM me if you would like a deeper explanation of sequential components in multi-phase power systems and I will put you to sleep faster than a six-pack alone at home in front of Knight Rider re-runs). Just know that zero sequence currents flow through neutral conducts and are additive. If you light your house with fluorescents, have a small den of computers or other non-linear loads, and create a parallel path for neutral currents through your amps, you will hear it.
Also, since these AC currents create their own 180Hz alternating magnetic field, nearby conductors can also have harmonic voltages induced; a single winding transformer for your listening pleasure when applied to close to audio gear!
Now, you want to get rid of these harmonic currents in your audio equipment? Do not create parallel paths for neutral currents (power strips can be your friend, Mate) or paths for neutral-to-ground currents.
Yes, the neutral service conductor running to your house is grounded at your service panel. Zero sequence current can flow through the neutral into your gear, through that neutral-to-equipment ground connection the new DIYer soldered/bolted together, through ground to the service entrance neutral, and right back to that big green padmounted transformer out side humming away at a nice fundamental 60Hz.
-electrically isolate your gear
-create distance between nasty carriers of harmonic current (stand-off is security)
Best of luck!
