I just purchased a used 50 amp Hughes RV220-50 Autoformer on Craigslist for $200.00. Plugged it in today, but the park I'm in has good power so even with both a/c's running we still show 118 v on my digital readout. When I plugged it in the lights did the flashing test they are supposed to do and settled on the orange light because the power is good. What concerns me is that although it is not supposed to be boosting the power, with the Autoformer plugged in, we are now showing 121-122 v on the meter. Is this normal? Seems like it should still show the 118 v from before me plugging in. Obviously it is not boosting 10%, it is only up 3v, but I am wondering why....Thanks,Brian

It may be that the source voltage has increased, line voltage can vary quickly and by 5%. It also may be that the Hughes has a threshold voltage that boosts power when reached. I'm not familiar with Hughes autoformer, maybe an inquiry to Hughes would bring the best answer. BTW, 122 V is a good value to be at, IMO. That is typical for my residential line voltage.

My understanding is that it doesn't boost unless the input is low. Mine doesn't.

Here's an excerpt from their web site:"Autoformers are used in industries to stabilize voltage and lower the operating cost of equipment. The Autoformer has 5 windings: 2 primary and 3 secondary. All models have surge and spike protection. When the unit is in Automatic and the park or input voltage is 116 volts or below, the output is 10% over the input. When the input is over 118 volts, the output is 2% over the input. "Looks like yours is working correctly.

On mine when voltage goes down the autoformer kicks in.

2% or 10% is the boost. 115 to 125 is perfectly fine.I don't connect my booster unless voltage is dipping below 110.

Hughes Autoformer question | Good Sam Community

13 Replies

huntram
Explorer
Sep 28, 2013
I thank everyone for their info and advise. I had not seen in the manual where it said, "When the input is over 118 volts, the output is 2% over the input". Obviously the Autoformer is working as advertised. I have put a surge protector inline.

In a year and four months of full timing I have not been in a too "hot" place yet where 2% would be an issue, however I have been in many places where 10% would be helpful! :)

I am thrilled to get a properly working current working 50 amp model so cheap.

Thanks agian!
Brian
wa8yxm
Explorer III
Sep 28, 2013
The problem is there are places I have heard of (never visited) where the shore power is a bit too "hot" and in those places a 2% boost is a bad thing.

However two plugs and two sockets later.. I'm direct connected.
gotsmart
Explorer
Sep 28, 2013
install a surge protector (of your choice) down stream of the autoformer. If the autoformer over-volts above the surge protector's max voltage threshold, the surge protector will clamp it.

Not ideal, but doable.
MEXICOWANDERER
Explorer
Sep 27, 2013
A few volts? Sheesh, an autoformer is a TRANSFORMER with a common neutral. It can do strange things to a waveform and even stranger things to a "meter". Load the turkey. Twenty or so amperes minimum. What does the voltage do then?
Old-Biscuit
Explorer III
Sep 27, 2013
Unhook the Hughes and see if voltage goes down.....if it does the Hughes is doing a small boost

As stated by 'Roadpilot' early this am "....input voltage is 116 volts or below, the output is 10% over the input. When the input is over 118 volts, the output is 2% over the input"

A 2% boost would only be 2.3V to 2.5V
huntram
Explorer
Sep 27, 2013
Thanks for the replies! I tried to call Hughes today but their customer support is only open Monday - Thursday.

Because the Orange light was on which I understand means it is NOT "boosting" the power it was concerning me. The highest I have seen it read is 123v, but it is hanging around 121v-122v. It was hanging around 117v-120v before I plugged in the Hughes.

It sounds like it is responding correctly. We are in Palm Springs right now, and the two a/c's like the 122v! :)

Thanks again!
Brian
wa8yxm
Explorer III
Sep 27, 2013
First, nothing wrong with 121 volts.

now... I have heard this from several Hughes users. It seems to provide a small boost no matter what.... the only advice I can give is.. Monitor it. if you have an overvoltage issue (over say 125 or for sure if over 130) unplug it.
DryCamper11
Explorer
Sep 27, 2013
I've studied the autoformer patents and built my own. The originally patented design would not boost the voltage if not needed, but it looks like the model they sell with three secondaries will.
time2roll
Nomad
Sep 27, 2013
2% or 10% is the boost. 115 to 125 is perfectly fine.
I don't connect my booster unless voltage is dipping below 110.
tandkj
Explorer
Sep 27, 2013
On mine when voltage goes down the autoformer kicks in.

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Hughes Autoformer question

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