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I'm going to display my ignorance here but I figure it is better to make sure about this than to not peep up:When we tweak by adding chokes and/or transformers in parallel on our AC circuit to improve the sonic (or, in the case of an AV system, visual) performance, are we adding a reactive power burden to the transmission line? I get the impression that these chokes and/or transformers are doing no additional work besides storing energy. If that's that case, I wonder if perhaps these devices are putting a reactive power burden on the grid? If that is the case, we might not notice it, because we only pay for active power, but the power company could be incurring transmission line losses nevertheless . . . ? Is this a non-issue? Or should we be bearing this aspect in mind?
Anyway, I am truly a NOOB at this sort of thing, so I would appreciate some enlightement on this. THANKS FOR YOUR KIND FORBEARANCE WITH, AND INDULGENCE OF, THE NOOB.
Chris
Follow Ups:
Power factor (pf) of tiny devices isn't much of an issue as stated. pf is an issue for the power companies. Most if not all end users whether home of companies, factories, etc., are inductive pf loads. The end effect is that at some point, even on lines serving only houses, the pf must be corrected. This is because even though the load is reactive and not "consumed" so-to-speak, it increase the total current that puts a load on the lines and also ultimately reflects back to the generating and transmission stations.The extra line load current can ultimately exceed the rating of the lines and also will cause losses in the conductors. Power companies routinely conduct distribution load studies (that was my first job as an EE) to forecast growth and anticipate where and when lines will need to be upgraded. This can be increasing the conductor gauge, adding phases (going from single to 3-phase) to spread the line drops, moving load from one phase of an existing 3-phase to another phase to balance the load on the three phases or it may be adding line capacitors to counter the pf of the load. You'll likely see capacitors on any local distribution line. They're often the box-like cans mounted on poles separate from the transformer drops. These may also be distributed on the line, not all located at the same point, depending on how long the line is and what the distribution is of the load.
Large companies that have large motors are billed additionally if their load is too excessive with regard to pf. Power companies generally have specific contracts with them that state that if the pf drops below some value (pf=1 is purely resistive), then they will be charge additionally. Those companies that have large inductive current draws often install their own capacitors to prevent this.
When I left the power company I interviewed with a steel company that made only rebar. They were in the process of installing an electronically controlled fast-switching capacitor bank for nearly instantaneous switching of capacitors. Their process involved lowering a high-current probe into a tank to melt the metal. The capacitive loading was so extreme that the power company was charging them enough to make an expensive dedicated capacitor system economically feasible. My sole job would have been to start up and manage the capacitor bank project. I declined.
I wouldn't be at all concerned with anything you'd do in the home. Your refrigerator alone will swamp almost anything else you might connect.
dlr
You have tweaked my ignorance without tweaking my nose.Free advice never gets any better than this!
:-)
With gratitude,
Chris
We are talking about 64 milliamperes of reactive current with a 5-Henry choke used on a 120 volt, 60 Hz circuit. This is 7.7 reactive volt-amps representing about as much current as a night light.Considering the total number of audiophiles around, and the fraction of those motivated to use such tweaks, the burden of this reactive current on the power grid is negligible.
Now, think about the 5 watts of real power dissipated by your door bell transformer 24/7. Everyone has one of these, along with wall-wart supplies for many other appliances that waste energy due to similar inefficiencies. These losses require generation capacity, and are a real problem for the grid.
In my area the power from the 69kV power line goes to a substation first. From there it is distributed to many large "neighborhood" transformers. From that huge tranny it is sent out again to several street transformers. I think any correction that you do at home is pretty well isolated from the original power lines. At the most it is quite insignificant.Also, if there is any "loss", reactive or otherwise, wouldn't it show up on your bill?
With regard to your last sentence, electricity utilities measure reactive power used by high demand customers and charge higher rates accordingly. (Some industrial users install power factor correction schemes at their factories to cut down on these higher costs.) But we small fry are not charged for reactive power.Inductors are said to consume reactive power . . . that makes me wonder if perhaps our use of inductors in AC power tweaking is putting a disproportionate burden on the grid . . . not that the sum total of what we do makes a great deal of difference compared with impact of indstrial users . . .
I work for a power utility, responsible for the automated meter reading of both commercial and residiential accounts.I don't know of any utility that charges by power factor. We do monitor it, more to keep demands balanced on 3 phase lines, but it's not billed that way. Billing is typically done based upon demand, not reactance.
I have seen plenty of off balance meter reads caused by reactive loads. You can see it at the specific meter, but any negative effect tends to stay at the site; these customers typically have power and current transformers before the meter, so they tend to mitigate the issue.
At a residential site, I really doubt that any type of reactance from an A/C filtering system would be worse than that of a fridge, heat pump, central air compressor, or any other large motors.
I agree utility companies do install a demand meter for large users of electrical power.I would also agree any inductor that would be used across the mains for an audio system would not be enough to cause any problem.
Problem with too much inductive reactance, heat..... It can cause feeders and panel boards to run hot. This in turn can causes fuses to blow even though the load may be below the rating of the fuse. Same is true for breakers. The electrical wire as well as the terminations temperatures will run above their normal temperatures and sometimes be very hot.... And in this case capacitors are added to bring the lagging out of phase current back in phase with the voltage. Thus PF correction. Problem? Motor Frequency Drives hate capacitor banks...
I think we can both agree that large scale inductive reactance is an industrial problem moreso than a residential one. And most larger industries will have the means to compensate for the loads, either through conductor oversizing, time shifting of loads, or even taking a feed directly from a substation.You are right, while capacitance is the mathematical solution to inductive lag, it doesn't always work well in practice.
that says "refer to Al Sekela ";> )
Given how many times I've also referred to Jon Risch, Duster, Alan Maher, et al..... LOLFYI, I refer to those whose experience is far greater than mine, who've written about a specific topic here, whose opinion I've come to trust from experience, and who can explain theory much better than I. It beats the t-shirts that say, "I'm with stupid => "
"Reach for the Alka Seltzer"
Vote for Pedro
Compared to the massive inductive loads presented by heavy industry - particularly motors - the tiddly chokes in our domestic appliances pale into insignificance.Industial users do pay for this - they're charged for reactive power usage (a unit called a var), & spend sigificant sums of money on power factor correction (huge capacitors!)
This is a layman's explanation by the way - I'm not an expert on this!
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