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RussWhite · 10-21-2010, 11:05 AM

Brad,

The EMS ( Energy Management System ) I mentioned is designed to handle up to a 50 amp service. At an RV park that is actually two 50A breakers tied together, each with a nominal 50 amp rating. The EMS can be purchased with a remote mounted display that will show you the voltage of each line ( phase ) as well as the current being drawn from that line. If your loads were equally balanced one could actually draw 50 amps on each line for a total of 100 amps at 120 volts, or 12KW ( kilo-watts ).
The device will actually work on a single phase 30 amp circuit as well assuming you have adapters to convert from 50A to 30A like most all coaches have or can be purchased.
The EMS monitors the voltage of each phase, not the phase to phase voltage. That is important since that supports a good neutral and if each phase voltage is correct, then by definition, the total will be correct. The device only allows power into your RV if each phase is within the range of 104 to 132.
Now shifting gears to the "autoformer"... That is a device that is capable of increasing the voltage before it goes into your coach. It looks for a situation where the voltage is too low ( varies by vendor ) and boots that voltage by a nominal 10% ( also varies by vendor ). I think the name "autoformer" is a play on the transformer configuration called an "auto transformer" which is a single winding transfer that can change voltage level but provides no isolation. My experience with the Hughes "autoformer" was not too good as the relays they used were actually not rated high enough for full load and would weld closed eventually requiring replacement. When I moved up to a 50A, two phase, voltage booster I changed vendors and have had very good luck with my PowerMaster VC-50 http://tweetys.com/powermaster-vc-50.aspx . Now, it's time for orange juice!

10-21-2010, 11:05 AM	#5
RussWhite Senior Member Join Date: Jan 2010 Posts: 346	Brad, The EMS ( Energy Management System ) I mentioned is designed to handle up to a 50 amp service. At an RV park that is actually two 50A breakers tied together, each with a nominal 50 amp rating. The EMS can be purchased with a remote mounted display that will show you the voltage of each line ( phase ) as well as the current being drawn from that line. If your loads were equally balanced one could actually draw 50 amps on each line for a total of 100 amps at 120 volts, or 12KW ( kilo-watts ). The device will actually work on a single phase 30 amp circuit as well assuming you have adapters to convert from 50A to 30A like most all coaches have or can be purchased. The EMS monitors the voltage of each phase, not the phase to phase voltage. That is important since that supports a good neutral and if each phase voltage is correct, then by definition, the total will be correct. The device only allows power into your RV if each phase is within the range of 104 to 132. Now shifting gears to the "autoformer"... That is a device that is capable of increasing the voltage before it goes into your coach. It looks for a situation where the voltage is too low ( varies by vendor ) and boots that voltage by a nominal 10% ( also varies by vendor ). I think the name "autoformer" is a play on the transformer configuration called an "auto transformer" which is a single winding transfer that can change voltage level but provides no isolation. My experience with the Hughes "autoformer" was not too good as the relays they used were actually not rated high enough for full load and would weld closed eventually requiring replacement. When I moved up to a 50A, two phase, voltage booster I changed vendors and have had very good luck with my PowerMaster VC-50 http://tweetys.com/powermaster-vc-50.aspx . Now, it's time for orange juice!