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Old 08-25-14, 05:32 AM   #21
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Originally Posted by AC_Hacker View Post

I'm thinking I would use one of these on my heat pump.

Think it might bring down the grid? They're pretty cheap.
There's no easy answer. It depends on the kVA size of transformer feeding your house, your load size relative to that rating and percentage of your load relative to total load at the time.

The billable charge is the bus fare you pay.

If you alone bring extra luggage and use three seats when there are plenty of empty seats, the effect is negligible.

If many people did this and reduced the number of revenue producing seats during busy time, they have to add buses to carry the displaced people, thus each of you is collectively contributing to wasted energy by wasting capacity. Answer? not "eco friendly".

Harmonics are even worse. They're like those people who bring loud arse kids who cause QUALITY of service issues to other customers.

Sheer stupidity like removing existing harmonics filter/PFC and advocating it online is like littering, bragging about it and telling kids littering is good and they should litter more. Advocating something that do not have it to begin with is more like encouraging the purchase of more polluting products.


Last edited by ICanHas; 08-25-14 at 05:38 AM..
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Old 08-25-14, 09:54 AM   #22
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thanks for agreeing 95% <G>

as for :
cost involved in the process of forcing the offending customer to pay the expense of putting his neighbor on a separate transformer or getting a court order to disconnect the harmonic load or install filtration device.

Would be very interested if you can provide even a SINGLE case law reference to this ever happening at a residential DIY level....

The first industrial case law IIRC is that Colorado Springs disconnected a certain Mr. N. Tesla from their grid when he shut down the system with an inordinate overload - maybe one could call N. Tesla a DIY, sure we would all be complimented.

Last edited by mejunkhound; 08-25-14 at 09:57 AM.. Reason: added tesla
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Old 08-25-14, 07:46 PM   #23
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Originally Posted by ICanHas View Post
Not all VFDs are the same. What is true to a harmonic reduced VFD do not translate to the same holding true for the stripped down bare minimum VFD one buys from Alibaba.
That particular VFD did not have PFC. In fact, it was a 480V VFD being run off a voltage doubler since he managed to get a 480V condensing unit (and the VFD to run it) for super cheap.
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Old 08-25-14, 09:25 PM   #24
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Quote:
That particular VFD did not have PFC. In fact, it was a 480V VFD being run off a voltage doubler since he managed to get a 480V condensing unit (and the VFD to run it) for super cheap.
All you've got is anecdotal evidence. The measured current could very well be incorrect if it was not measured correctly using a right instrument.

Please provide the kVA, kW, THD and 3rd, 5th, 7th, 9th and 11th harmonic percentages.
It's not the high VA to kW ratio per se that's the problem. It's the harmonic content, especially the 3rd harmonic that affects power quality to other customers as well as disproportionately higher losses in transformers.

Did you advocate the dirty power drawing diode-capacitor front-end and convince him to do ti?

Thank you ~


Quote:
Originally Posted by mejunkhound View Post
as for :
cost involved in the process of forcing the offending customer to pay the expense of putting his neighbor on a separate transformer or getting a court order to disconnect the harmonic load or install filtration device.

Would be very interested if you can provide even a SINGLE case law reference to this ever happening at a residential DIY level....

The first industrial case law IIRC is that Colorado Springs disconnected a certain Mr. N. Tesla from their grid when he shut down the system with an inordinate overload - maybe one could call N. Tesla a DIY, sure we would all be complimented.


Quote:
As far as DIY folks 'polluting' the grid, what a crock - there are so few DIY that use multi HP non PFC VFD that it is a teaspoon in the ocean.
One install would not affect it at feeder level. It would affect it at the nearest PCC or causing enough localized pollution to affect delivered power quality to neighbors. What's your ground for calling it "what a crock"? 3kW 6kVA >100% THD is easily over 10% of demand on subdivision transformer.

From the IEEE draft:

"Employing electronically-commutated motors (ECMs), the input of a variable speed heat pump resembles a large switch-mode power supply (e.g., 3 kW or more). The ECM is a dc brushless motor with stator construction similar to a three-phase ac induction motor. The stator winding current is sequenced and switched creating a rotating magnetic field. This switching is performed electronically by an inverter. The rotor uses permanent magnet construction.
Conventional heat pumps have a current THD of 13% with around 9% third harmonic content; some of the newer ECM designs have current THD values of 123% with the third harmonic content of 85%.
Because of the large load, there is concern that it would only take relatively few installations of this type of heat pump to cause voltage distortion problems. In [2], the authors found the voltage distortion on a distribution feeder reached 10% when the penetration rate for these variable-speed drives reached 10%, i.e., when 10% of the homes installed the new ECM designs. Though a 10% THDV would be deemed unacceptable by most of us, it does give us a sense of how much of a particular nonlinear load would cause problems on a residential feeder.

[2] International Standard IEC 1000-4-7, “Electromagnetic Compatibility (EMC), Part 4: Testing and Measurement Techniques”.

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Old 08-25-14, 10:28 PM   #25
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Did you advocate the dirty power drawing diode-capacitor front-end and convince him to do ti?
No, he did it well before I found the video.

He's actually very knowledgeable about HVAC and power electronics.
subcooledheatpump - YouTube
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Old 08-25-14, 10:40 PM   #26
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But you didn't answer my question regarding THDi values on that system. This thread is about power system pollution. You literally posted YouTube videos from those people all over the place. I'd rather you didn't use my threads for ad space for that stuff especially since that don't address anything that is being discussed about here.

Here's food for thought.
Some people think HVAC systems should use dangerous refrigerant and drive technology that is devoid of power pollution prevention technology or use photoelectric conversion energy source laden with serious amounts of toxic cadmium with power electronics parts manufactured with all sorts of dangerous chemicals that presents the same type of issues as lead paint and asbestos at the end of life, then hate on people who drive Hummers and Excursion, because that's the trendy thing to do among millennial.

It's hard to tell if that's any better or worse than using thermostat with lots of mercury, mercury flame sensor, PCB capacitor PSC motor, R22 refrigerant and drive a 1965 V8 muscle car with chlorofluorocarbon 12 filled AC.

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Old 08-25-14, 10:59 PM   #27
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Cadmium telluride photovoltaics - Wikipedia, the free encyclopedia
Quote:
Cadmium, a heavy metal considered a hazardous substance, is a waste byproduct of zinc refining therefore its production does not depend on PV market demand. CdTe PV modules provide a beneficial and safe use for cadmium that would otherwise be stored for future use or disposed of in landfills as hazardous waste. Mining byproducts can be converted into a stable CdTe compound and safely encapsulated inside CdTe PV solar modules for years. A large growth in the CdTe PV sector has the potential to reduce global cadmium emissions by displacing coal and oil power generation.
If that still bothers you, stick to the silicon based panels.

Also note that a lot of cordless power tools are still using NiCd batteries. Lithium works better and is less bad for the environment, but is flammable, requiring proper mitigation of the hazard. Really no different than advocating the use of hydrocarbon refrigerants to replace fluorocarbons. (And that unit in the video does not use hydrocarbons, just R134a.)

I strongly advocate repairing electronic stuff that is worth repairing and selling/donating the rest (uneconomical to repair or otherwise no longer useful to you) to the educational/DIY market. In particular, students can learn a lot repurposing old electronic stuff.
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Old 08-25-14, 11:01 PM   #28
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Ok., so when do you think the general public will catch the wave and start building their own homebrew air conditioning system s with dirty vfd driven power supplies? And when will they go back to good old core and coil setups? My guess on both counts is never.

You said yourself that the majority of manufactured devices have built in power factor correction.

So what does this really have to do with anything not completely wingnut in nature? Sounds like a lengthy armchair discussion to me.

What I want to hear more about is a harmonic eating power cleaning device. Something that I can rig up to keep all that dirt the power utilities don't want back anyway.

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Old 08-25-14, 11:11 PM   #29
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Ok., so when do you think the general public will catch the wave and start building their own homebrew air conditioning system s with dirty vfd driven power supplies?
As I said, even one unit can have adverse effect depending on distribution transformer size.
It is about "eco friendly" so if the energy consumption that is inclusive of transformer loss and reduced reduction in your neighbors' AC motor efficiency overwhelms your point of use energy savings, you failed at reducing energy use.

Quote:
And when will they go back to good old core and coil setups? My guess on both counts is never.
When PoCo starts assessing penalty for harmonics which becomes easier than its ever been as smart meter enjoys greater penetration.

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What I want to hear more about is a harmonic eating power cleaning device.
We're already getting our feet wet with this upcoming problems which is why the future is in mandatory integration of such cleaning parts into every harmonic producing equipment much the same way as catalytic converter mandate on cars.

I already linked you to it. The ABB link. Some inverter mini-split A/C units already have a very effective harmonic mitigation built into it. The ABB version and the one built into some modern electronics is the active PFC type.

Here's a passive type:
http://www.artechepq.com/assets/files/SinglePhase.pdf

That type of passive filter was very common for somewhat older IEC spec computer power supplies as well as US spec electronic ballasts. That sort of external mitigation is not needed if it is already taken care of within the device.

ANSI requires THD of <32% for lighting ballasts. This was a requirement created in response to earlier unfiltered ballasts causing problems from excess harmonics. The old design was well before electronic ballast load became a big proportion of commercial building load.

The increased use of non-linear load is headed the same way as they gain share in percentage of load supplied to homes.

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Old 08-25-14, 11:28 PM   #30
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And then someone finds a practical solution to the arcing issue with HVDC (380V or so), making PoL PFC obsolete. HVDC just makes a lot more sense when most (residential scale) alternative energy sources are DC, as are most electronic devices. Large motors are served by PoL inverters, giving them the benefit of variable speed and efficiency optimization at the same time.

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