Switching to shore power

Discussion in 'General RVing' started by skipl@buz.net, Jul 7, 2004.

  1. skipl@buz.net

    skipl@buz.net New Member

    Our new-to-us Class A has a 30 A. power cord for shore power. The power cord does not have to be plugged into a receptacle in the utility compartment to use generator power.

    I understand that there is a relay somewhere that is controlled by plugging into shore power. When you plug into shore power, the relay operates to connect the coach 120V circuits to the shore power and disconnect them from the generator output.

    When I was setting up this past weekend, it was hot and humid outside. I had the generator running to keep the A/C's running.

    When it is that hot, you sure hate to shut down the A/C while you transfer to shore power, then wait 2 minutes before you can bring them back online.

    The owner manual is silent on the matter and I would assume that it would not be a good idea to simply plug into shore power while the A/C's are running to avoid that shutdown period. But if you could ...............

    Has anyone experienced this, on purpose or not?

    Skip
     
  2. rlmurraysr59

    rlmurraysr59 New Member

    Switching to shore power

    I have ran the generator while plugged into the land line. No problem that I can see. It will still only supply 120 volts. As far as the air conditioner is concerned, you could start the motorhome engine and use the dashboard air conditioner while you wait the two minutes. Or make sure the coach is cool enough before you shut off the generator.

    Don't remember ever running into the problem you are inquiring about. The air conditioner isn't going to kick in until it resets anyway if it does kick out when you switch for generator to land line. Guess you could try it and see. Still under warranty?
    Good Luck
     
  3. Troubleshooter

    Troubleshooter New Member

    Switching to shore power

    Yes, it is a pain to have to shut down the air conditioners before switching over to commercial power after running on generator power.
    However, if you take into consideration that the change over relay must break one circuit and make another; running your air conditioner while the change over is activating, is asking for trouble.
    Have you ever arced a car battry? Did you notice the big flash, and bang when you did it?
    Same thing happens to the change over relay contacts when you 'Hot Switch', or switch under load, from one power source to another.
    It is only a matter of time, when doing this, that you will be paying for a new change over ralay assembly, or worse yet, paying for an air conditioner compressor.
    I recommend you keep you hand away from your wallet, and continue to turn off all loads before switching from Generator to Commercial, or Vice Versa.
    Another note; with most rigs that have a change over relay system, if you are on commercial power, and decide to test your generator, it will automatically 'Hot Switch' from commercial to generator. Not Good.... If you want to run your generator at the same time you are connected to commercial power, turn off the generator circuit breakers before starting it up.

    Only One Old Fellows Opinion
     
  4. rlmurraysr59

    rlmurraysr59 New Member

    Switching to shore power

    I concur with Bill's answer. I think it would be better to wait the two minutes to turn the conditioners back on after switching from the generator to the land line. I got to thinking about it and I have only started my generator one time when I was plugged to a land line. And I had the circuit breakers on the generator turned off. I was servicing the generator and just wanted to test for oil leaks.

    Better safe than sorry. I just had a hassle with my front air conditioner because Fleetwood uses a device called an Intellitec Climate Control. My front air conditioner didn't work for two years. Coleman was at a loss because they couldn't tell me where to take it to get it fixed. Dealers don't touch airconditioners anymore, they contract it out to someone else, and the only Coleman dealer that I could find said he wouldn't work on it with it mounted on a Southwind motorhome. Didn't say why.

    Turned out that it was a noise coming from the converter that caused an interferrence in the Intellitec Climate Control. Had to replace the converter. Sounds a little weird to me but then I have run into a lot of weird stuff with this Fleetwood product.

    Hope you can work it out to your satisfaction.
     
  5. skipl@buz.net

    skipl@buz.net New Member

    Switching to shore power

    Thanks, all. I figured the answer would be no, but I'd hate to miss the opportunity to keep the cool going.

    Yeah, I do have the dash air running, too, since the engine has to be running to operate the slides and the levelers. But it would be nice to be able to get a head start on cooling down the rear.

    Troubleshooter, what you say about the arcing makes perfect sense the way you explained it. Like you say, it might work a few times and then ...............

    Mr. Murray, you also answered my other question about the Intellitec. Thanks for the additional insight.
     
  6. Gary B

    Gary B Senior Member

    Switching to shore power

    Hi guys, you have it a bit worng here about the generator switch relay & shore power. Shore power is instant power(the switch over relay is normally switched to the shore power side)when the generator is started the switch over relay (actually it much more than just a relay switch)as the generator gains rpms the voltage goes from 0 to 30, 60, 70,80,90,100,110 etc and the freq go up also when the generator voltage reachs 115 VAC and the freq is also at 60 then the switch over realy closes and the generator is on line, this generally happens in about 40 seconds. Having your rv on shore power and firing up the generator will hurt nothing becase its always a hot switch no matter how you do it and turning the circuit breakers off only put addition load on them. When you have the generator on line and plug into shore power nothing happens as the switch over is on generator and will continue to be untill you shut down the generator, and when the voltage drops it switchs over to shore power. What really causes damage to the electrical system is what is refered to as windup voltage or the gradual increase in voltage as the rpms increase, thats why the power is always on shore power and the switch can sense that the generator is at full operating specs. The confusion over 2 min. may come from the fact that all the newer air conditioners have a 2 / 3 min shut down when shut off to prevent damage to the compressor, thus if you shut the AC off and then turn it right back on the fan will run but the compressor will not kick in for 2 / 3 min.

    Hi RonR59, just to let you know every major mfg uses the intellitec controller or a very simular type switch all of witch are sensitive to another bad piece of electronic equippment putting out EMF transmissions, your problem was caused by a partially failed converter which was a solid state type. This is not just a Fleetwood cutting corners thing.
    The problem with rv service centers not working on AC is they can't justify a trained certifed AC tech to do only AC's (at least not up in the northern part of the country) and so they try to get home heating & AC companys to do the work (as roof airs use R22 the same as home units) rv AC's are sealed units requires tapping in service ports and for the most part are on top of the rig and so AC techs don't want to climb around on your roof, mess around with installing service ports etc.
    Hope this helps with the understanding of how it works. :) :laugh: :cool: :bleh: :approve:
     
  7. skipl@buz.net

    skipl@buz.net New Member

    Switching to shore power

    Gary, thanks for your insight. That is wonderful.

    My more important and potentially expensive question has to do with the Intellitec unit. Click here for the link.

    Could you take a minute to give me your view on that problem?

    Thanks a bunch.
     
  8. Troubleshooter

    Troubleshooter New Member

    Switching to shore power

    Gary,
    Thanks for your insight, however, evidently your system is different from the Intellitec 50 Amp Transfer Relay Delay that is mounted in my RV.
    Per Intellitec's information, this unit has a 15 second delay when it senses an input from the generator. However, when the generator is removed the changeover to commercial power is instantaneous.
    In regards to there not being any damage done when Hot Switching under a high load, I must respectfully disagree with you. From my experience, any time a magnetic contactor breaks one circuit and makes another; arcing takes place. Under minor loading, the arcing is minimal, however under heavy loading of the circuit, the arcing can be major, and glazing/pitting of the contactor contacts takes place. If this Hot Switching under high loading is done frequently enough, irreversible damage will be done to the contacts. Hot Switching under minimal loading rarely does excessive damage, and most contactors will last indefinitely.
    Having had to change out many many Radio Transmitter Antenna Changeover Relays, I can personally attest to the damage arcing can do. Granted, 60Hz is not as damaging as radio frequency, however it still can and will cause damage in the long run.
    Therefore, I must respectfully stand by my previous statements
     
  9. Gary B

    Gary B Senior Member

    Switching to shore power

    Hi Bill, I have no disagreement with you in that the higher the amp load the more pitting/arcing you'll get and yes it can and will seriously damage the contacts over time. I belive if you check further the Intellitec change over will not at least is not suppose to change over until the gen reachs 115 vAC and 60 Hz, after that time it changes over in 15 sec.? I did not mean to inply that no damage will occurr from high load hot switching, I was trying to explain how the system works and that you can not elimate a hot switch, which you can't but of course you can reduce the load. I have routinely checked the switch over time and it generally is about 40 sec. but this is not set in stone, alot will depend on the condition of the generator, switch relay etc. :) :laugh: :cool: :bleh: :approve:
     
  10. rlmurraysr59

    rlmurraysr59 New Member

    Switching to shore power

    Gentlemen, I think we have reached an agreement on this question. Turn the air conditioners off, let them reset, turn off the generator, plug into the shore power, and then restart the air conditioners. That will completely eliminate any chance of damage to the control units or the generator. I have heard of some shore power lines having a surge in them when you initially plug in. It isn't worth it in the long run. The answers were great. I, for one, learned a lot.

    Thanks.
     

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