Autoformer vs surge protector

[drstimpy]

If you have one of these:

Do you need one of these?

[drfife]

Yes

[edatlanta]

These two products service entirely different purposes except low voltage. The autoformer will increase low voltage where the EMS will shut off your power if the voltage drops below 104v. But the EMS protects from a bunch of other stuff that the autoformer doesn't address. Again, different products.

I totally believe in the need for an EMS to the point that I have two. One is in service daily and another one as a spare in case the primary one is damaged and has to go back for repair/replacement (lifetime warranty BTW).

[drstimpy]

So...autoformer to shore power and ems to autoformer? Makes sense to me[emoji848]

[wingnut60]

If the autoformer "trips" doesn't it have to go back for service?

[drstimpy]

Don't know...looking at both items

[Old Scout]

Just guessing but think that if you are going to use both [ie different functions], you would want the autoformer to be in line first to "bump up" low voltage before the PI shuts you down. Despite all kinds of claims about the "magic" of the autoformer and how it "makes more volts while dropping amps" out of nothing, I am not sure how the autoformer and the PI would work in tandem. The PI is evaluating and if needed, will shut down, based on a whole host of parameters and potential conditions that might impact incoming shore power. Personally, I still havent gotten by the "magic stuff" but perhaps someone who knows how both products work, can explain it.

[TechWriter]

Originally Posted by Old Scout

Despite all kinds of claims about the "magic" of the autoformer and how it "makes more volts while dropping amps" out of nothing, I am not sure how the autoformer and the PI would work in tandem.

First, there's no "magic" to an auto former or voltage regulator. It just uses one of the Ohm's law variants: P = IE or Power (watts) = I (current in amps) x E (voltage in volts).

Assuming Power remains constant, if you boost voltage, then current must drop. The equation also shows why people use an auto former in the first place -- when voltage drops, then current rises which is bad for motors (ACs, fridges, etc).

I use a Surge Guard voltage regulator + a Surge Guard EMS in series as the manufacturer recommended.

However, I've heard of others who have used various combinations.

[sleggio]

I have both the PI hardwired 50 amp EMS and a Hughes Autoformer, the autoformer is first inline. And yes if the Autoformer take a hit it will take out the sacrificial surge protector, and it can be replaced by the factory. With more and more rigs with 3 A/C's and park power fluctuations being what they are, I would not plug-in without them.

[Steve Ownby]

Originally Posted by sleggio

I have both the PI hardwired 50 amp EMS and a Hughes Autoformer, the autoformer is first inline. And yes if the Autoformer take a hit it will take out the sacrificial surge protector, and it can be replaced by the factory. With more and more rigs with 3 A/C's and park power fluctuations being what they are, I would not plug-in without them.

I'm with you and have this same combo. I went one step further and put a PI surge protector only in front of the Hughes.

[jimbrv]

I created a situation where neither of these devices would have saved my A/C. I have a progressive HW50 EMS (hard wired unit). I intentionally created a bad shore power connection by connecting my coach to the a 15A household receptacle with a 50 foot 12 gauge extension cord connected to the RVs 50A shore power cord. The idea was to create a connection that didn't have enough current to cover a large load, in this case the A/C. When the A/C compressor tried the start the EMS contactor just chattered at a very fast rate. A call to Progressive revealed that the pull in voltage for the contactor is 70vac. When the A/C tries to start the voltage dropped below 70 volts due to the poor power source causing the contactor to open which removed the load from the circuit at which time the voltage increases to line voltage (122vac) and the cycle of open/close starts over again eventually damaging the EMS, A/C unit or both. I was told by the Progressive tech that the HW50 can't deal with the inductive load of the A/C motor and the only way to solve the problem is to install an autoformer. Trouble is the Autoformer only works between 95 and 115 volts according to their website. Above and below those voltages the unit is passive from the stand point of increasing line voltage.

The situation I created would probably be rare but it could exist and according to my research there is no protection from it.

[Cummins12V98]

I have a 50A Hughes Autoformer. I was specifically told to put it first before the surge protector. I installed mine in the compartment with the cord power reel.

[tampabiker]

Originally Posted by Cummins12V98

I have a 50A Hughes Autoformer. I was specifically told to put it first before the surge protector. I installed mine in the compartment with the cord power reel.

Hey Cummins, I am seriously considering putting an Autoformer in my Mobile Suites 5th wheel. I was going to put it in front of the sliding doors in my basement until I read your post here. How big is your hose reel bay? I measured mine, and it's right at 13" tall. The Hughes website says the 50a version is 12" tall, and if that includes the handle, I think it will fit in mine. I'd sure appreciate your feedback on this!

[tampabiker]

I meant to say cord reel.