30 amp variac instead of an autoformer?

Hi Dick,

There are always losses. What I wish to do is protect the (expensive) air conditioner in my RV.

Gdetrailer wrote:

pianotuna wrote:
Hi GDE,

I had already eliminated that unit as it is not quite big enough to handle the surge from the air conditioner.

The A/C was tripping the campground breaker not the RV breaker.

An Autoformer, line conditioner with AVR will NOT HELP you at all.

There is no free lunch, an autoformer may "boost" the voltage on the output but in doing so it requires MORE CURRENT at the INPUT.

In many respects it will most likely end up tripping the campground breaker even faster.

The device you are seeking would essentially break every known laws of physics.. Those types of devices are known as "Over Unity" devices (IE making energy from nothing).. Many have tried and ALL have failed at making perpetual motion or energy devices.

Sorry, but that is the way it works.

Seems like it might still work. It is my understanding that an A/C will draw more current when input voltage is low so when it is fed with correct voltage the decrease in input current might be enough to offset the current draw into the AVR which of course will be higher than the A/C current since the AVR is boosting the line voltage.

Dick

Hi Gde,

I am not looking for "over parity" devices. I'm looking for a voltage boost. I know that costs more amps.

pianotuna wrote:
Hi GDE,

I had already eliminated that unit as it is not quite big enough to handle the surge from the air conditioner.

The A/C was tripping the campground breaker not the RV breaker.

An Autoformer, line conditioner with AVR will NOT HELP you at all.

There is no free lunch, an autoformer may "boost" the voltage on the output but in doing so it requires MORE CURRENT at the INPUT.

In many respects it will most likely end up tripping the campground breaker even faster.

The device you are seeking would essentially break every known laws of physics.. Those types of devices are known as "Over Unity" devices (IE making energy from nothing).. Many have tried and ALL have failed at making perpetual motion or energy devices.

Sorry, but that is the way it works.

Hi GDE,

I had already eliminated that unit as it is not quite big enough to handle the surge from the air conditioner.

The A/C was tripping the campground breaker not the RV breaker.

pianotuna wrote:
Gde,

Nice points. The campground I end up at in hot weather is old. Their 30 service drops like a stone in hot weather to the point of sometimes blowing the breaker with *only* the air conditioner on drawing 1900 watts. The voltage hovers at 105 which is way below my comfort zone of 108. That number is if I turn off all power to everything except the air. I.e. fridge on propane, water heater off, and battery charging off.

I was hoping the Magnum load support would keep the voltage up--but it doesn't work that way. I did not try dialing down the input amperage which I could attempt, because my old flooded batteries were on death's door.

Ideally I'd love to have an autoformer with six steps of boost and six steps of buck. I know those are available in Mexico--but that's a long round trip for me in the RV.

What you are looking for is known as a "line conditioner" with "AVR" (Automatic Voltage Regulation).

The biggest one I can find is a Tripplite LC2400 which is a 2400W conditioner/AVR.. Unfortunately that is only 20A..

But it only costs $190 on Amazon right now..



SEE HERE

" 2400W 120V Power Conditioner with Automatic Voltage Regulation (AVR), AC Surge Protection, 6 Outlets
Maintains usable 120V nominal output to sensitive electronics during severe brownouts and overvoltages. Prevents surges and spikes from damaging circuitry. Filters out potentially disruptive line noise.

Ideal for computers, routers, modems and home theater components
Corrects under- and overvoltages in 89V–147V range
Protects against spikes with 1440 joules of surge suppression
Monitors power status with front-panel diagnostic LEDs
Features 6 outlets: 4 NEMA 5-15R and 2 NEMA 5-20R"

Keep in mind, even though a AVR can "boost" the voltage on the output, it doesn't come "free".. It does this at the expense of a HIGHER INPUT CURRENT DRAW.

That 20A AVR will draw more than 20A on the input side with a full load on the output under "boost" conditions.. So even a 30A version would run into the very same limitation and it would be possible your A/C would trip the campground breaker instead of your RV breaker..

Gde,

Nice points. The campground I end up at in hot weather is old. Their 30 service drops like a stone in hot weather to the point of sometimes blowing the breaker with *only* the air conditioner on drawing 1900 watts. The voltage hovers at 105 which is way below my comfort zone of 108. That number is if I turn off all power to everything except the air. I.e. fridge on propane, water heater off, and battery charging off.

I was hoping the Magnum load support would keep the voltage up--but it doesn't work that way. I did not try dialing down the input amperage which I could attempt, because my old flooded batteries were on death's door.

Ideally I'd love to have an autoformer with six steps of boost and six steps of buck. I know those are available in Mexico--but that's a long round trip for me in the RV.

pianotuna wrote:
Hi,

I've been looking for a 30 amp autoformer for some time. I wonder if this item would "fill the bill".

30 amp variac $169

Here is the company listing:

variable ac transformer

Are you planning to baby sit it 24/7?

It is not a regulated output, no standard variacs are regulated which means you would have to monitor the input voltage and then manually turn the dial up and down.. Seems to me it would be a dull boring job..

They are nothing more than a one sided transformer which has extra windings with a fully variable center tap..

No automatic voltage regulation which means if you are using to boost a low input voltage and the input voltage suddenly rises to say 130 on the input the output will rise to 140 or more volts..

If the input voltage is high and you are dialing it down to 120V and the input voltage drops to say 100V now you output voltage might drop to 80V..

Spend the money and buy a proper designed system, this one is not for you..

2oldman wrote:
Are variacs capable of increasing low voltage?

Yes, but within a input voltage range.

Variacs are a "buck/boost" transformer, windings are continuous from zero to 130V AC for the output for a given input voltage which I will assume should be about 110 or 115..

One major issue to note is this is NOT LINE ISOLATED IN ANY WAY SHAPE OR FORM..

These are typically used in trouble shooting electric equipment that are having issues at full line voltage but can be used other applications like a huge inefficient light dimmer or a small boost or even buck to line voltage that is a little low or a little high..

A major downside to this device is it is NOT AUTOMATICALLY "regulated" what so ever, so if line voltage increases so doe the output voltage.. If the input voltage decreases so doe the output voltage..

Misuse of this device may result in you accidentally smoking your stuff instead of saving it..

Hi Chris,

Nice--but I don't need 240 volts out, so it won't be in my stocking come Christmas. Or am I wrong about the output levels?

Chris Bryant wrote:
How about this one Only 3000 watts, but at a glance looks automatic.
Not sure if it will regulate without step up or down, though.