Autotransformers: Good or Bad?

[hoppers4]

I'm considering getting an autotransformer to protect my A/C in campgrounds with inadequate wiring/low voltage at the post. This is a good thing for my A/C but not such a good thing for my neighbors on the same circuit. So, what's your opinion of autotransformer use?

Here's a link to one opinion Autotransformer Use: "Stealing Power?"

[norty1]

I have been in CG's that had posted signs prohibiting them.
I have never been in a CG where I needed one and my EMS would shut off the supply of the voltage got to low.
Un necessary expense IMO.

[SouthCo]

Yep a Progressive Industries EMS would shut the power off in a low voltage situation and protect your AC.

[hoppers4]

Actually what I'm interested in is not an EMS but an autotransformer. An autotransformer will kick your voltage up by 10% when the post voltage drops below 117VAC. However, because it steps your voltage up and you draw more current, the other posts on the same circuit will lose a small amount of voltage due to line loss from the campground feed for that circuit.

An autotransformer would allow me to keep using my A/C in a low voltage situation whereas an EMS would not. I've been in campgrounds where I've seen the voltage drop to 106VAC and I was really concerned about my A/C.

[BigJohnD]

I have one. Frank's autoformer for 50 amp. I pretty much never use it. Hadn't in a few years. BUT, you bet I would if I needed to. Lost an AC In our first rig due to low voltage, so never again. Auoformer is cheaper than AC. I have the EMS also, but your dead in the water if low voltage, unless you have an autoformer.

[hoppers4]

BigJohn, that's interesting that you haven't had to use it for years. I was in several this June (cross country trip using quite a few KOAs) and also a couple the year before that had low voltage. Perhaps I just need to use better campgrounds.

[BigJohnD]

hoppers4, not sure. Oddly enough, both the parks we experienced low voltage in were in the same area. Lost the AC in one of them. We've used it a few times here and there, but in the last few years all has been well between voltage monitors and ems. Run of luck I guess.

[tnchuck100]

They are GOOD!

I have one. I have used it once. I am glad I have it and will use it whenever necessary.

Stealing power? That is a statement made by people who do not understand electricity. The electric distribution system has regulators at the substations and throughout the system. They ARE, in fact, auto-formers. Big ones!

Yes, you will draw slightly more power from the pedestal after including your auto-former but at the same time your air conditioner is running more efficiently on the increased voltage. Almost a wash. But you are NOT "stealing power". Read the last paragraph in the OP's article link.

[hoppers4]

That's kinda the way I was thinking Chuck. I have a pretty good grip on the I/V/P relationship and have a hard time viewing it as stealing. I have an even harder time shutting off my A/C when it's really hot out or worse yet burning it up because of inadequate infrastructure.

[VicS1950]

Curious.

I'm familiar with autotransformers and step transformers in power distribution. I'm not at all familiar with autotransformers intended for RV use. Are most units a fixed 10% or is it common to have non-load tap changing to closer trim in the voltage? I suspect multiple taps would add cost to the manufacturer so they aren't common.

An aside. The article cited above declared that most RV loads are resisitve. I disagree in that the large percentage of power used is for air conditioning, fans, refrigeration compressors, inverter/chargers, etc. I wouldn't consider those loads resistive. Even though the traditional 12 volt interior lamps are resisitve, when connected to shore power they are powered by the inverter/charger.

FWIW. vic

[hoppers4]

Vics, I've been able to find about three different autotransformers. Besides Hughes (one 10% step), there's Frank's (an 8% and 16% step but more expensive than Hughes), and one other brand that I don't remember.

[tnchuck100]

Vic, these work just like the regulators with tap changers. Just not quite as sophisticated. Most are automatic boost/no boost.

[VicS1950]

Thanks all for the replies and info. vic