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Chuck48 · 11-21-2014, 09:18 AM

This is all complicated. To make it easier to understand, think of it this way. If you have a EMS and the wiring at the pedistle is wrong, it will show 30 amps and limit you to 30 amps therefore not overloading the neutral. If you don't have a EMS, you could draw too many amps, with no device to limit it, it could over load the neutral, if the pedistle is wrong. Since you have a EMS you're ok, except you cannot use up to your potential on amps.

Alan_Hepburn · 11-21-2014, 06:23 PM

Quote:

Originally Posted by gemini5362

Like I said in my earlier post I think that what everyone is saying about the neutral makes sense i just have to think about why that is. There seems to be something wrong in thinking that if you have two 180 degree out of phase circuits the neutral could be carrying zero current if they load is exactly the same. I need to think about that for a while.

You need to remember that AC stands for Alternating Current - if you use an oscilloscope to view the voltage you'll see a sine wave that swings up and down around 0V at a frequency of 60 cycles per second. The waveform will alternate from approximately 180V above ground to 180V below ground - the value we use to quantify that voltage is something called the Root Mean Square voltage, or about 120V.

Now when you have a single hot line installed you have that line swinging above and below ground, with the return line completing the circuit, carrying the same current as the hot line. Now, add a second line, that is 180 degrees out of phase: when L1 is at +120V then L2 is at -120V and the return currents in the neutral are also 180 degrees out of phase. Since currents add when L1 is carrying +20A and L2 is carrying -20A then add +20 and -20 and you get 0.

ChasA · 11-22-2014, 08:40 AM

Good job Alan.

Bumps · 11-22-2014, 08:56 AM

Alan: That's a great explanation. (I'm a visual learner). Thanks! \ken

gemini5362 · 11-22-2014, 08:42 PM

Quote:

Originally Posted by Alan_Hepburn

You need to remember that AC stands for Alternating Current - if you use an oscilloscope to view the voltage you'll see a sine wave that swings up and down around 0V at a frequency of 60 cycles per second. The waveform will alternate from approximately 180V above ground to 180V below ground - the value we use to quantify that voltage is something called the Root Mean Square voltage, or about 120V.

Now when you have a single hot line installed you have that line swinging above and below ground, with the return line completing the circuit, carrying the same current as the hot line. Now, add a second line, that is 180 degrees out of phase: when L1 is at +120V then L2 is at -120V and the return currents in the neutral are also 180 degrees out of phase. Since currents add when L1 is carrying +20A and L2 is carrying -20A then add +20 and -20 and you get 0.

Thank you for this. I am actually very familiar with everything you said. I know what kirchoff's law is and how it works. It is just something I never thought about in depth. When you analyze a circuit you plug in this math and this is the answer. This questions made me stop and think something that I know better than to do. In reality current is the flow of electrons along the wire. I just was thinking about how if you have 50 amps flowing from phase L1,L2 and 50 amps out of phase from L2,L3 the math says that it is equal to zero if both currents are of equal amplitude but out of phase by 180 degrees. I know the math. But if I have a toaster plugged into a receptacle on L1,L2 and an identical toeaster plugged into a receptacle on L2,L3 Both toasters are going to work but the math says that L2 is going to have 0 amps on it but L1, L3 is going to have the amount of amps the toaster uses to heat up. I appreciate your attempted explanation but I am just curious how you have zero electrons moving in L2 but you have current flow through L1, L3

nothermark · 11-23-2014, 06:31 AM

I think it depends where you look at the circuit. Draw it up and the summing junction is the common buss at the panel. What cancels out is current back to the pole transformer center tap. I think that is where they come up with the double the current idea. There is no other place where it can happen.

SewFishy · 11-23-2014, 07:45 AM

Electrical theory is nice and EE's can discuss it till the cows come home but I didn't see your problem fixed.

Check your dishwasher circuit. Do you have one? Breaker off or need full reset? Washer removed? Panel on Vectra (07) monitors dishwasher 120V AC line to enable 50 amp L2 side at input switch. If breakered, disconnected or loose connection in dishwasher or line to panel your panel will drop to 30 amp and enable load control. Your pole monitor/will show L1 and L2 good. Bad dishwasher breaker will also cause fault. Drove us crazy in South Dakota where it was cold. Now in Louisiana where it is not cold.. but problem fixed. Good Luck.

RV Manager · 11-24-2014, 05:00 PM

First off all thanks for all of the responses, I have enjoyed the dialogue concerning how to test etc. Honestly much of it was beyond my comprehension, but nevertheless educational.
So here is what I have done. Turned all breakers, including dishwasher, washer dryer, inverter etc on and off several times. Plugged and unplugged the power source, tried running off of the generator, etc. had an electrician look at my breaker panel, he says I have 240 on both legs, but my coach is only operating on 30 amps.
I am open to any new ideads, thoughts or suggestions.

nothermark · 11-25-2014, 08:34 AM

I don't know how the power management works in your coach but I can say this. IF you have 230 VAC coming in to the transfer switch or beyond the problem is in the power management system. I'd call the factory help desk and see if they had any ideas. It sounds like whatever they sense with and/or control the 30/50 changeover with has a problem.

gemini5362 · 11-25-2014, 08:59 AM

Quote:

Originally Posted by Catcoach

First off all thanks for all of the responses, I have enjoyed the dialogue concerning how to test etc. Honestly much of it was beyond my comprehension, but nevertheless educational.
So here is what I have done. Turned all breakers, including dishwasher, washer dryer, inverter etc on and off several times. Plugged and unplugged the power source, tried running off of the generator, etc. had an electrician look at my breaker panel, he says I have 240 on both legs, but my coach is only operating on 30 amps.
I am open to any new ideads, thoughts or suggestions.

First of all thank you for the interesting question. It questioned some concepts I have known for 50 years and gave me a chance to have an interesting theoretical discussion with friends something I have not done in years.

Now as to helping you. I honestly think sewfishy gave very explicit explanation of how your problem could have happened. I know you reset the circuit breaker but he also mentioned broken wires or bad connections. I have never played with an EMS my coach does not have one. Does your dishwasher work ? If it does that would tell you whether or not you have power to it. If it does then I think the advice to call the coach manufacturer would be wise at this point. If you have correct input power and the EMS is not recognizing it either the monitoring line for the EMS has a problem or the EMS itself is bad.

Oh and for what it is worth. I am past the point of discussing this with EE's I am putting in a call to my friend with a Masters Degree in physics next.

OLYLEN · 11-25-2014, 09:01 AM

Again check your transfer switch. You have the power with the Gen, but not on shore. The only common area IS the transfer switch. If you have a HANDYMAN available 5 minutes and you will have an answer. And in 10 either fixed or what you need to order.
PLEASE READ THE OP's FIRST POST. ALL THE THEORY IN THE WORLD DOESN'T COUNT WHEN YOUR NOT ADDRESSING THE PROBLEM.

LEN

gemini5362 · 11-26-2014, 12:32 PM

Quote:

Originally Posted by OLYLEN

Again check your transfer switch. You have the power with the Gen, but not on shore. The only common area IS the transfer switch. If you have a HANDYMAN available 5 minutes and you will have an answer. And in 10 either fixed or what you need to order.
PLEASE READ THE OP's FIRST POST. ALL THE THEORY IN THE WORLD DOESN'T COUNT WHEN YOUR NOT ADDRESSING THE PROBLEM.

LEN

You are quite right about reading the post first. I misread where the OP said everything worked with generator.

Did you notice post #36 where the OP said an electrician checked the coach circuit breaker panel and he has 240 volts across both legs. That would eliminate the transfer switch as the problem.

One thing I might have missed but exactly what is not working. I realize AC units are not working but If my understanding of the Power monitoring system is correct It will allow either air conditioner to work just not both at the same time. If he turns one on at a time will they both work.
Is there anything else that is not working.
I think the Power monitoring system either the sytem itself or wiring for monitoring has a problem if everything will work as long as you stay under 30 amps.

RABBITFISH · 11-27-2014, 10:37 AM

Well I am really wanting to find the final answer to this problem as stated by the OP. These forums contain a wealth of information, and I sure appreciate all the helpful responses that educate me on problems that I have not faced yet. I just love following along and learning so much about these favorite toys of ours!
Please let us know what you find out was the problem to start!
Thanks again! And good luck!

RV Manager · 11-27-2014, 11:45 AM

I promise that I will update this thread when I get the problem fixed. Now working 6 days a week at Amazon,10 hr days, so it may be awhile before I can call Winnebago for help. In the interim I am managing on 30 amps by balancing my need for coffee and heat. Amazing what a coffee pot plus in amperage.