Question Hughes Autoformer install?

[osuallen]

If its 2800 its Magnum. They put Victron 3kw inverters in a few of them in 2022 but that might have just been a supply chain thing,

It was supply chain. I got the Victron in my 2022 DSDP from the factory.

 

[Joe Hogan]

A reason to make the Autoformer installation modular. The Electrical code in 2020 now allows campgrounds to ban the use of Autoformers. Granted if the Autoformer is installed inside the RV no one would be the wiser, However, I like to follow the rules and respect the campground wishes so I can easily disconnect (unplug) the Autoformer should it be necessary.

Discussion of the Code restrictions:

RVelectricity: Hughes Autoformer – A cure for low campground voltage?

By Mike Sokol Dear Readers, Not a week goes by without me receiving at least a few emails and questions about the Hughes Autoformer. This is advertised

www.rvtravel.com

 

[Rich W.]

There is clearly some confusion here because the NEC and NFPA are saying that these devices draw more amperage to make up for low voltage, balancing the equation. And the only time the NFPA gets involved is when there is risk of fire - over-heated electrical in this case. But I guess I should say perceived or theoretical risk, because the NFPA does go a bit over the top.

But Hughes says: “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 [tapping point] and raising the voltage.” By doing this it is also lowering the total available wattage. Something to keep in mind - you can‘t run as much stuff, but at least what you run will be at the proper voltage

The only way it can do this without drawing additional amperage from the pedestal is by lowering the available amperage to the coach (Hughes’ claim), robbing amps to pay volts. This makes sense (again balancing the equation) to protect what you are running from low voltage, but it also reduces your 50amp service, depending on the adjustment, on the coach side of the autoformer. I’d say this is ok, since, if the need exists, you are in a low power situation anyway. Better to regulate it on your side of the pedestal.

Like Mike Sokol, I’d be interested to find out which is true. The test would be simple to perform, but would also be expensive because you’d have to buy an auto-former. So this question will have to be answered by a disinterested third party in possession of an autoformer, and with the curiosity and wherewithal (power supply) to perform the test.

My guess is that Hughes is correct in this case, and the NEC and NFPA are addressing all auto-transformers generically without regard to the specifics of the Hughes device. Otherwise they would have to test all auto-transformers and then specify which ones meet the code and which ones don’t.

 

[Joe Hogan]

Thinking about the Autoformer “stealing“ power from the Park. Hughes says that this is impossible. The Park has allocated 30 or 50 amps, depending upon your rig, to your spot. Draw more than the circuit is designed to provide and the circuit breaker will cut power. Looking at it this way, they appear to be correct.

 

[Kevin D Pem]

UL approved is a requirement to meet code! What that means is the device has been tested, no need to be retested, unless modified.
So the issue that the NEC has is the protection of the grid infrastructure. Transformers are measured in VA (volt amps) close to watts, but there are calculation differences.

Let's take an example and examine it shall we?

We know that as battery voltage drops amp draw increases in order to supply the same watts. If using an inverter to supply the appliance, as the battery voltage drops the inverter demands higher amperage from the battery to supply the designed output voltage. Most quality inverter data confirms this.
When the demand is high enough and the battery voltage is low enough the inverter protects the battery by disconnecting. This protection is not available on the grid, that is why Brown outs occur.
It really is about grid Transformer sizing. When fixed location boost Transformers are installed, they were installed to overcome voltage drops, but the supply Transformer was installed with the anticipated VA ratings, portable boost transformers don't take into account grid equipment, nor protect it in any way.

The reason grids have brown outs is the system has been over taxed. I agree with NEC on this.

 

[Kevin D Pem]

Thinking about the Autoformer “stealing“ power from the Park. Hughes says that this is impossible. The Park has allocated 30 or 50 amps, depending upon your rig, to your spot. Draw more than the circuit is designed to provide and the circuit breaker will cut power. Looking at it this way, they appear to be correct.

Not true! One needs to understand how service power is calculated, it is a percentage of full loading. Look into the NEC for guidance.

 

[Rich W.]

The question is whether the Hughes unit draws more amperage from the grid side to maintain 120v to the coach, or reduces available amperage on the coach side to bring voltage up to balance the “volts x amps = watts” equation, lowering available watts to the coach in the process.

Again, from Hughes: “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.”

The NEC/NFPA ruling seems to paint all auto-transformers with the same brush, assuming that they all raise voltage by raising amperage maintaining maximum load capacity. But Hughes is saying the Autoformer steps-down amperage on the coach side of the pedestal to step up voltage thus lowering the maximum load capacity - the opposite of the concern for parks owners and grid operators.

The test I mentioned earlier would confirm which is true. If it is as Hughes says, then there would be no impact on the park side of the pedestal. If Hughes is misrepresenting their product, then yes there would be a problem. But from a regulatory standpoint, I can see how it would be easiest to just say they all violate the electrical code.

 

[Kevin D Pem]

10% of 120 =12v=108vac 50amp× 108=5400w 50ampsx120= 6000w so it is assumed the primary wire size is limited to 5400w. And although this may be the case it will have an overheating problem if you demand 6000w from it, long before it limits the current. Transformers are designed for a set volt amps. And though that is what they are designed to handle does not mean they can't be abused.
The real issue comes when many units are installed and cause problems with the grid side Transformers.

Not to be a naysayers, the better solution is the system designed to supplement the grid in your rig using the inverter and batteries.
That is elegant!!!

If you want isolation from spikes and isolation transformer is the best,.

 

[Rich W.]

10% of 120 =12v=108vac 50amp× 108=5400w 50ampsx120= 6000w so it is assumed the primary wire size is limited to 5400w. And although this may be the case it will have an overheating problem if you demand 6000w from it, long before it limits the current. Transformers are designed for a set volt amps. And though that is what they are designed to handle does not mean they can't be abused.
The real issue comes when many units are installed and cause problems with the grid side Transformers.

Not to be a naysayers, the better solution is the system designed to supplement the grid in your rig using the inverter and batteries.
That is elegant!!!

If you want isolation from spikes and isolation transformer is the best,.

I definitely agree that this is not the most elegant solution and I’m saving my pennies for a new ( bigger) inverter that will include load support and a better battery bank to back it up (but not just for this reason). And I have a decent size solar set-up by RV standards. I also think the autoformer is way over-priced for what it is, although not necessarily for what it does. It may be cheap insurance.

As far as abusing the autoformer goes, I guess if you insisted on trying to pull a full load with it in amperage-reduction-voltage-maintenance mode something would have to give, but I would assume that there is thermal protection built in. In fact I believe I read somewhere that it will shut down in the above scenerio.

 

[Kevin D Pem]

I definitely agree that this is not the most elegant solution and I’m saving my pennies for a new ( bigger) inverter that will include load support and a better battery bank to back it up (but not just for this reason). And I have a decent size solar set-up by RV standards. I also think the autoformer is way over-priced for what it is, although not necessarily for what it does. It may be cheap insurance.

As far as abusing the autoformer goes, I guess if you insisted on trying to pull a full load with it in amperage-reduction-voltage-maintenance mode something would have to give, but I would assume that there is thermal protection built in. In fact I believe I read somewhere that it will shut down in the above scenerio.

Most of thermal shut down schemes can produce sizable spikes. So that can be troublesome, would have to know what they use if that is the case. I would say a zero crossing circuit would have to be used to avoid any problems, I'm wondering if they would disclose!