RV.Net Open Roads Forum: Tech Issues: Generator Problem

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Help and Support  |  Contact

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Generator Problem

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 
Sponsored By:
Little George 97

Cape Girardeau

New Member

Joined: 07/01/2012

View Profile



Good Sam RV Club Member

Offline
Posted: 07/01/12 06:13pm Link  |  Print  |  Notify Moderator

I have a generator problem that was caused when my little granddaughter started the seven KW Onan generator in my 2003 Cross Country class A motorhome while it was hooked up to an electrical outlet..
Now I have no electrical shore power connection and the generator will not start.
I still have RV battery power, and the motorhome engine will start and run.
Can anyone who has had this same experience give me any advice on what needs to be done to repair the problem? Thank You

I just returned from Branson, MO after being gone over the Fourth of July week that was the reason I was unable to reply to everyone for their timely good advice.
I wanted to thank everyone for their information related to my granddaughter starting the generator while the motorhome was plugged in to a 110 wall outlet.
My disaster turned out not to be a disaster after all. When I returned to the storage garage to check for a transfer switch as recommended and to also re-check the fuses, good fortune was smiling on me.
When I attempted to start the generator it fired up on the first attempt and was working correctly.
I found that the reason there was no shore power working in the motorhome was for whatever the reason the breaker on the wall outlet had tripped.
It turned out that there were not any problems with the electrical system or generator in the motorhome, everything worked just fine while we were gone this last week.
Thank all of you for taking the time to address my problem. Little George

* This post was last edited 07/08/12 09:30pm by Little George 97 *   View edit history

SWD

Land of Living Skies

Senior Member

Joined: 06/07/2005

View Profile


Offline
Posted: 07/01/12 06:36pm Link  |  Print  |  Notify Moderator

The fact that your coach was plugged in to an electrical outlet when the generator was started plays no role. If the transfer switch was wired in properly that would have prevented any backfeed into the grid. The transfer switch usually has three positions, on (grid power) off and on (gen power). I think that you should check your transfer switch and breakers in your main panel. I can start my generator even when plugged into the grid.

Kirk

Livingston, Texas.

Senior Member

Joined: 06/17/2001

View Profile



Good Sam RV Club Member

Offline
Posted: 07/01/12 08:21pm Link  |  Print  |  Notify Moderator

The fact that the shore power was in service has everything to do with the problem. RV generator sets are connected so that an auto transfer device will favor the generator as a power source. If your air conditioner or some other heavy load was in operation when she fired up the generator set, the surge which it put through the ATS when it transferred power would have been huge and could have been as serious as a lightning strike.

Shore power and the generator are both alternating current and to shift loads like that would have done it with then in different phase relations to the sine wave pattern of current. It may have been as much as 180 degrees out of phase, which would be a shift in voltage instantly of 240V! It probably burned the contacts in your ATS and may have completely destroyed it. Power should never be shifted while under load and that is the #1 reason for failure of ATS devices.

Just so that you know, I am a 40 year, electrical/mechanical service tech by trade.


Good travelin! ........Kirk
Professional Volunteer
Fulltimer for 11 years,
URL: www.adventure.1tree.net


pulsar

Lewisville, NC

Senior Member

Joined: 12/30/2001

View Profile



Good Sam RV Club Member


Posted: 07/01/12 07:45pm Link  |  Print  |  Notify Moderator

Moved from Forum Technical Support to Tech Issues.

MrWizard

Traveling

Moderator

Joined: 06/27/2004

View Profile



Posted: 07/01/12 08:36pm Link  |  Print  |  Notify Moderator

there was another post recently regarding the same thing
shore power was on and generator was started

it sounds like the trasfer switch is fried, that is why no shore power
also the arc over may have taken out the generator control board and maybe more that is why it won't even start, start by checking the genset front panel and control for blown fuses

now I ask is this MH 30amp service or 50 amp service, because there is a difference in the transfer switches

the 50 amp usually contains TWO contactors with a mechanical interlock
when one is powered/energized, the other cannot pull in and make contact

however many 30 amp mh's use one contactor, and a time delay relay in the hot side in series with the generator, so it is possible to get a load arc and even an arc between the two services, genny and shore

and before somebody suggests it has to be 50amp ... wrong

i have had two different mH's with 30amp service that had 6.5kw OPTIonal onans, and could run both a/c's from generator


Options, always have options, and the journey goes much smoother
....

Connected thru Verizon with HotSpot WiFi using a Samsung Galaxy Nexus


Little George 97

Cape Girardeau

New Member

Joined: 07/01/2012

View Profile



Good Sam RV Club Member

Offline
Posted: 07/01/12 06:59pm Link  |  Print  |  Notify Moderator

Thank you for the information; I will see if I can find where the transfer switch is located.
Little George 97

MrWizard

Traveling

Moderator

Joined: 06/27/2004

View Profile



Posted: 07/02/12 09:40am Link  |  Print  |  Notify Moderator

you have the wrong concept of a transfer switch in lower voltage applications
you can't or don't deliberately shut down a power grid , therefore the contractors involved are humongous


in backup generator emg applications , the generator starts 'after' the power failure and then comes online 30 > 60 seconds
no active loads are switched, everything that was running got stopped, involuntarily shut off then restarted after the generator comes on line
even during once a month scheduled emg generator test and maintenance it is mainly a test of the auto start and run functions ,Not a full power load transfer

in rv,s the transfer switch, should be called a selector or mode switch
it is not rugged enough and not designed to be switched while a/c , large converter. etc... are being powered

you are supposed to unplug shore power before turning on generator power
or
turn off generator before plugging into shore
we have a few people on here that insist on keeping the generator running the A/c units and plug into shore power before stopping the generator

and every year we get a post or two similar to this thread

although this one was Not the OP's fault..

pianotuna

Regina, SK, Canada

Senior Member

Joined: 12/18/2004

View Profile


Offline
Posted: 07/03/12 07:29am Link  |  Print  |  Notify Moderator

Hi,

I knew there was a reason I do not trust ATS in Rv's. As usual, the OEM rv makers have chosen the lowest priced piece of technology possible.

I'm so glad I read this thread as I was about to install an ATS for an auxiliary power circuit for the water heater. Back to manual plugs for me! (i.e. cheaper, and fool proof, signed "the village idiot".)


Regards, Don
Full Time in a Kustom Koach Class C 28'5", 256 watts Unisolar, 875 amp hours in two battery banks 12 volt batteries, Magnum 3000 watt PSW inverter.

SWD

Land of Living Skies

Senior Member

Joined: 06/07/2005

View Profile


Offline
Posted: 07/01/12 10:00pm Link  |  Print  |  Notify Moderator

Kirk wrote:

The fact that the shore power was in service has everything to do with the problem. RV generator sets are connected so that an auto transfer device will favor the generator as a power source. If your air conditioner or some other heavy load was in operation when she fired up the generator set, the surge which it put through the ATS when it transferred power would have been huge and could have been as serious as a lightning strike.

Shore power and the generator are both alternating current and to shift loads like that would have done it with then in different phase relations to the sine wave pattern of current. It may have been as much as 180 degrees out of phase, which would be a shift in voltage instantly of 240V! It probably burned the contacts in your ATS and may have completely destroyed it. Power should never be shifted while under load and that is the #1 reason for failure of ATS devices.

Just so that you know, I am a 40 year, electrical/mechanical service tech by trade.



Interesting...but isnt that how an ATS is supposed to work, being able to switch power from generated to grid even under load conditions? Must be unique way of switching for an RV. Undoubtedly poor quality ATS switches that are used on RVs?

Former Field Engineer for SIEMENS High Voltage Power Engineering Div.

* This post was edited 07/02/12 07:10am by SWD *

SWD

Land of Living Skies

Senior Member

Joined: 06/07/2005

View Profile


Offline
Posted: 07/03/12 07:03am Link  |  Print  |  Notify Moderator

In back-up emg situations the initial transfer is under no load, as you rightly say, however on a resumption of services the ATS switches full load from standby mode to grid mode. As you have correctly stated the RV ATS switches are merely "mode" switch rather than a true ATS switch. My concern would be one of "backfeeding" the generator through the grid if the unit remains plugged in to the shore based receptacle. That would certainly cause issues.

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 

Open Roads Forum  >  Tech Issues

 > Generator Problem
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2014 RV.Net | Terms & Conditions | PRIVACY POLICY | YOUR PRIVACY RIGHTS