Autoformer pros and cons

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
Status
Not open for further replies.
Alas, power factor varies with voltage on induction motors.

At the ideal voltage (Which may be much lower than the proper starting voltage) it's 1/1

I've seen Power factors as low as 0.5 till the Power Factor Controller did it's thing and lowered the voltage
 
Well.. as I said, I've seen some significant changes in power factor when I used the Green plug, and the change in voltage was not much more than 10 percent if that.

Read up on green plug operation theory, they explain it way better than I can
 
John:
I'm trying to find info on Green plug, but the only thing I'm seeing is related specifically to DC power.  Can you point us to the info you are referring to?
 
Ned said:
I wouldn't use an autoformer, as it will increase the current drawn as the voltage is raised, further exacerbating the problem.  Autoformers cause more problems than they solve and I recommend against their use under any conditions.
Click to expand...
Sir, you could not be any more wrong. The Current that is drawn from the Shore power stays exactly the same. The Extra voltage that is drawn comes from the Automatic Transformer (Autoformer) which simply runs off the shore power no different than your coach would. Such a device that sucks extra electricity from a source would recieve a nobel prize and or probably end up being illegal. Your neighbor getting low voltage while you're not would happen regardless if you or someone else were running an Autoformer
 
Ian.. I have seen the Volt and amp charts and  you are wrong.. Current from the shore outlet WILL Change.. HOWEVER it will not exceed the ratings (Else the breaker will break.. the circuit that is,, (Trip)).

There is a whole lot of argument as to the direction of the change but independent lab tests have shown an increase in most cases.

Volts times Amps times Power factor = Watts  (YES folks it is not Volts times Amps.. PF is in there too)

The higher the voltage to the compressor motor the LOWER the PF.. (There are limits to this statement)

However if the voltage goes too low..Damage happens.. The autoformor raises the voltage into the safe level.. THis may slightly lower the Power Factor but the effect on amprage may or may not be what you tink

But that is on the transformer OUTPUT

On the input side PF has gone down,  Voltage has not changed.. So CURRENT MUST INCREASE.
 
Hi, Ian ... welcome to The RV Forum!

You're confusing Current and Power.  Conservation of energy means the Power must remain constant.

Ohm's Law says Power = Voltage x Current.  If the Autotransformer is increasing the output voltage by 10% it must do so by drawing 10% more current from the source, otherwise it is creating power out of nothing ... and that would rewrite the laws of physics and qualify for a Nobel Prize.

The variable in this discussion, since most people use an Autoformer to allow the operation of an air conditioner, is does the air conditioner become more efficient at higher voltages, or is the additional current drawn at lower voltages just caused by the Power = Voltage x Current relationship?

If the air conditioner is more efficient at higher voltage, is the increase in efficiency enough to compensate for the extra 10% current the Autoformer will draw from the campground wiring?

Without this information we're all just spinning our wheels.
 
Lou Schneider said:
Hi, Ian ... welcome to The RV Forum!

You're confusing Current and Power.  Conservation of energy means the Power must remain constant.

Ohm's Law says Power = Voltage x Current.  If the Autotransformer is increasing the output voltage by 10% it must do so by drawing 10% more current from the source, otherwise it is creating power out of nothing ... and that would rewrite the laws of physics and qualify for a Nobel Prize.
Click to expand...
It is not doing that. If it raises voltage it lowers current. No magic.

From the horse's mouth:
The Autoformer DOES NOT take power from the park.

It does not affect the park or input voltage, or make electricity.

What it is doing is changing the voltage - amperage relationship, lowering the amperage and raising the voltage. Since appliances run better on higher voltage, lower amperage, less overall power is used from the park, and better service is enjoyed from your RV
Click to expand...
https://www.hughesautoformers.com/index.php?option=com_content&view=article&id=34&Itemid=157


Mike
 
Reviving a 7 year old topic just to debate the different physics across the multiverse :(
 
Ned said:
Reviving a 7 year old topic just to debate the different physics across the multiverse :(
Click to expand...
On the bright side I think that is something with which to be proud. I don't think I have run across any forums that have such old threads--that are for the most part still valid--that I see here.

Granted it could imply that RV technology doesn't move ahead very much, or very quickly.




Mike
 
Some RVers are packrats, we never throw anything away :)
 
It's long overdue time for me to publish my article on autoformers  :-[
 
NY_Dutch said:
Don't forget to include the notation that the NEC prohibits them for RV use.  ::) :D
Click to expand...

It would be very useful to have a citation for that information.

I found several references to this part of the NEC but not having access to the code, I can't verify it, but have no reason to doubt its veracity:

NFPA 70 - National Electrical Code? 2011 Edition

Chapter 5 - Special Occupancies

Article 551 - Recreational Vehicles & Recreational Vehicle Parks

Section 20 - Combination Electrical Systems

Paragraph E - Autotransformers

"Autotransformers shall not be used."
Click to expand...
 
Ned said:
It would be very useful to have a citation for that information.
Click to expand...
Sure! Check Article 551 - "Recreational vehicles and Recreational Vehicle Parks", Section 551.20 - "Combination Electrical Systems", Paragraph E - "Autotransformers". The entire paragraph reads: "Autotransformers shall not be used."

That's from the 2014 edition of NFPA 70, and the wording is identical in previous versions but I'm not sure if the article numbering is the same.
 
Status
Not open for further replies.

Latest posts

Members online

Total: 600 (members: 12, guests: 588)

Forum statistics

Threads
132,094
Posts
1,390,248
Members
137,813
Latest member
CheriRv
Back
Top Bottom