Voltage Too Low for an Autotransformer

[cj5 jeeper]

While on a trip up the Oregon Washington coast last summer we had low power in four parks, twice on hot days we fired up the generator so we could run both ac's. Not being one to endure what can be cured, I now have a Hughes 450 Autoformer installed. (where people that think they steal power, and people that want a free one can not see it) While I was at it I installed a hard wired Progressive Industries Energy Management System it is not only a surge protector, but it will shut off power if voltage is to high, or to low. This is installed after the transfer switch, so it moniters both shore power and generator. Years ago I installed plug in surge protectors for all the electronic appliances, (microwave, tv, dvd, refer, etc) This is an inexpensive way to protect them if you do not have something for the whole motorhome.

[RVDude]

todd - the results are very consistent...

Test #1
116.1v * 29.4a = 3413w which is certainly within expected tolerance for a 30amp breaker in the pedestal supplying 104v * 30a (breaker) = 3120w. It's less than a 10% over-amp but certainly within experimental and breaker tolerance. Especially given the load was AC units which fluctuate markedly in demand. A pure resistance load would be more stable for this test. I'll also bet the breaker would eventually trip at this slight over-amp particularly with the slightest fluctuation in current demand, unless, as is typical, the ac compressors gradually unload slightly as they run longer in AC mode.

Test #2
Running w/o the PM you have 1 AC at 106v and now due to lower voltage it will demand more amps to perform the same amount of work (a.k.a. watts). This is also consistent with v * a = w where the AC requires a set w and the a will change with v. So the ac now wants 17.4a and trying to run double that will clearly blow the breaker (17.4a * 2units = 35a).