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Topic: Low Voltage and Appliance Performance (Read 1906 times) previous topic - next topic

Re: Low Voltage and Appliance Performance

Reply #25 –
Hi Neal,
  You sure have a clean utility bay!! And your 50 hardwire installation is well done.

Raymond & Babette Jordan
1997 U 320
Raymond & Babette Jordan
1997 U 320
1998 Ford Explorer XLT

Re: Low Voltage and Appliance Performance

Reply #26 –
Wow.  I thought I was prepared with the 50 amp portable Surge Guard.
Dwayne Keith
1992 U240
3116/MD3060

Re: Low Voltage and Appliance Performance

Reply #27 –
I don't quite understand the physics of it.  If a device works to change something, it is still work!  Work uses energy, so, a device that takes something in and changes it, uses energy.  This means that less comes out, whether the device makes heat, or there is a coil in it, or something.  Otherwise we have the proverbial "perpetual motion" thing going.
If you have, say, 30 amps coming in at 100 VAC, and put it through a device, it is hard for me to believe that you can get 25 amps at 120 VAC.  This then limits what you can use on the line.  Use near the 25 amps (if the device lives up to their claim) and the voltage will drop anyway and you will still burn up the appliance.
When I used to teach troubleshooting, I used a water hose as an example with pressure being voltage and volume being water flow.  Put your finger over the end of the hose and you get pressure, but the volume reduces.  There is no free lunch.  Anything you do to the hose, whether you make it longer or stick a valve somewhere in the line or make it do work, it lowers something, either the pressure or volume.
So it is, I believe, with electricity.  Watts=Volts X Amps.
Do I have a distorted view of it? Is the device snake oil?
Michael Baldacchino
'97 40' U320

Re: Low Voltage and Appliance Performance

Reply #28 –
Hi Again, Barry,
We just had a family reunion and I was helping the DW with all the good reunion stuff.  As the teenagers said, it was "Wicked Awesome", .
Now back to the Autoformer issue.  Let me apologize up front, because it will take a bit of explanation, so please bear with me.  I'll post this because several others have expressed interest and I know that Autoformers are like AGM Vs. Gel Cells.  These (among other technical topics) are highly polarizing and there are no absolutely correct or incorrect final answers.  But everyone deserves quality input in order to be able to reach reasonable conclusions that apply to them
I wasn't clear , I guess, in what I was trying to say.
 
I said:
"I don't care for Autoformers because there is no such thing as free power to you without impacting others on the grid.  I'd be happy to walk you through the mathematics of that, if you would like to see the technical proof.  But, essentially, if you are able to use more current (because you have an Autoformer) and you are running  more appliances, there is less available current and voltage for your neighbors in an already overstressed power grid in any improperly or poorly designed park power grid situation."

Like any step up or step down transformers, Autoformers, indeed  change the input to output current and voltage ratios in proportion to the ratio of their primary to secondary transformer windings .  And those relationships, in the simplest transformer form are:
If Np = the number of turns in a primary transformer winding
Ns= the number of turns in a secondary transformer winding
Ep = Voltage applied to a primary winding in Volts AC
Es = Voltage measured across a secondary winding in Volts AC
Ip = the current in a primary winding
Ep = the current induced into a secondary winding
Then:
Np/Ns = Ep/Es (directly proportional)
Np/Ns = Is/Ip  (inversely proportional)
And therefore,
Ep/Es = Is/Ip  (inversely proportional)
Thus, if you decrease the input voltage going into a step up transformer and you then build circuitry that senses that the transformer output voltage is also decreasing (because the input to output windings ratio determines the output voltage) and you then build circuitry that automatically changes the number of turns of secondary windings available, thus adding secondary windings to bring the voltage back up to the desired target voltage,  you have built yourself an "Autoformer" (they actually do it in a few electronically controlled step increases, not in analog fashion).  And yes, mathematically, as the input voltage decreased, output current increased, but you added secondary turns and brought the output voltage (and therefore current)  back to the desired target, so input current has not now been appreciably changed.  And all that you have to pay for is the "50 Amp Autoformer" itself ($500 or $600 maybe?) and the transformer "losses" which are advertised to be "1 amp at 50 amps of rated output load".
It's good that the Autoformer Owner has used one of several options that has protected his inductive loads (anything with windings) by raising the operating voltage while keeping the current drawn from his power pole nearly the same, but let's look practically at what he has really saved in terms of the park grid and his neighbors.
The figure attached below is a well accepted set of graphs that shows (in general terms) the relationship of supply voltage to various small induction motor characteristics (like for our AC compressor and fan motors).
For a Penguin, DuoTherm, 13,500 BTU AC compressor and fan motor at full load at rated design voltage (115VAC, 60 HZ, 1PH) :
PF = 0.88 (from Dometic online literature)
Power = 1570 Watts
Current = 15.500 amps (for two motors, 12.4 amps for the compressor, 3.1 amps for the fan)

At 10 % low VAC at the power pole (104 VAC, 60 HZ, 1PH)
PF = 0.924 (From Graphs)
Current = 16.323 amps (a 0.823 amp increase, which equals roughly one 95 Watt light bulb)

At 15 % High VAC at the power pole  (132 VAS, 60 HZ, 1PH)
PF = .748 (From Graphs)
Current = 15.887 amps (a 0.387 amp increase, which equals roughly one 45 Watt light bulb)

Now to the crux of my distaste for Autoformers.  If I am on a power source that, for whatever reason, is low or high in voltage, I am made aware of that condition by the EMS protective device that I have chosen.  If the voltage is low, then I look for ways to reduce my load, use the generator or move to another site, as appropriate and I may use the equivalent of one, or at worst two, 95 Watt light bulbs more energy for a while in doing so.
However, if I were on an Autoformer, it appears to me that I might not even know that I'm on a struggling, or poorly designed grid.  And worse, because I'm unaware, I may be using additional appliances that I don't really have to use, just because I don't know, thereby drawing more current through the fixed resistance wiring of the park, creating more voltage drop and making the problem worse, or even much worse for my neighbors.
Then if I'm a really bad neighbor and want to make things really, really worse, when someone comes to my door and asks me to consider shedding some loads or to consider stopping the use of my Autoformer, I'll tell them that I paid for the site and the power and I'll go out of my way to make their problem even worse.

We had that happen in a Buffalo NY park.  We woke up in the night to our single AC (I only had one turned on) going on and off because the  EMS was tripping on low voltage. The EMS would reset and then trip off again a few minutes later.  I suspected Autoformers since the park had had a low voltage earlier on in the evening (106 VAC) and two high end SOB's, with four AC's each (as well as Autoformers),  had moved in after dark, one on either side of us.  Outside, at the power pole, I watched my power dip well  below 104 VAC for minutes at a time as their various AC compressors cut in and out in the 90 degree heat and humidity of the middle of the night.  Since it seemed as though each was using three if not all four AC's, I tried their doorbells and, through their intercoms, got immediate and very angry responses from each neighbor.  I eventually asked for assistance from park management, after working up through several levels of park staff.  Management agreed that I had a problem but wouldn't help me out because their rules forbid me from using my generator, my neighbors were part of a larger Rally and they weren't about to irritate the $$$$$'s, the park had no other 30 or 50 amp sites (that they could fit us into) and, by this time, both Autoformer coaches had made it very clear to both of us that they were perfectly entitled to run all eight AC's if they wanted to, whether they were creating a problem or not.  TOUGH S--T!
Along with the grandchildren, we had a very sleepless night and a very sleepy next day at Niagara Falls.  We won't patronize the park again, not even to inquire if it is under new management/ownership.

So under one scenario, I could keep it simple (as well as less expensive, by the cost of one Autoformer) and use maybe one extra 100 watt bulb for a bit, while I sort things out.  Under the other (Autoformer) scenario I could potentially use 3 or more, 15,000 BTU AC's than I don't actually need to use  (roughly equal to fifty-five, unneeded 100 Watt light bulbs, or 50 unnecessary TV sets simultaneously, or five or six coffee makers and/or microwaves ovens at the same time............. "just because"  I'm not interested in the Golden Rule or in being a Team Player or in just plain using common sense conservation  ). 

I'm not at all adverse to anyone using an Autoformer to protect his/her appliances, as long as they conserve and try their best to be good neighbors.  But, several times I have found that Autoformer owners have no idea whatsoever that they are having even the slightest impact on their neighbors (for example, just by running one AC that their neighbors can't) and they are generally the same ones that brag loudly about how many additional excesses they are able to enjoy, "just because they have an Autoformer, and their neighbors don't".  Thus my distaste.

Hope this sheds some technical light, Barry.  Pardon my emotional excesses. 
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Low Voltage and Appliance Performance

Reply #29 –
Quote
I'm not at all adverse to anyone using an Autoformer to protect his/her appliances, as long as they conserve and try their best to be good neighbors.  But, several times I have found that Autoformer owners have no idea whatsoever that they are having even the slightest impact on their neighbors (for example, just by running one AC that their neighbors can't) and they are generally the same ones that brag loudly about how many additional excesses they are able to enjoy, "just because they have an Autoformer, and their neighbors don't".  Thus my distaste.

Hope this sheds some technical light, Barry.  Pardon my emotional excesses.
Neal

Thanks Neal for that explanation.
I 'll admit it will take me a little while to absorb it.
It appears the answer means going deeper than what is on the surface.
I will dig deeper into this now so I can have a better understanding.
It is great to have such a wide range of expertise on the Forum.

I do use the Autoformer when necessary if I am paying for a 50amp site and my transfer switch is going on & off and it means no power at all. I came back from a hike with that situation. I don't know how long it was doing it. I think my transfer relay will need to be replaced due to the arcing. I can't go without at least 1 A/C. But I do agree in minimizing my use to and not exploit the situation.
Thanks again for the thorough explanation.

The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"