Generator power

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  #1  
Old 08-28-12, 03:01 PM
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Generator power

I just bought a 5500 watt 30 amp generator. I planned on using it for my camper during dry camping and power outages. The generator has 4 120vac 15 amp receptacles and 1 4 prong 120/240vac 30 amp connector. The adapter I made consist of a 4 prong male plug and a 3 prong RV plug with a 1 foot piece of 10/3 wire connecting them. I only connected 1 of the hots on the 4 prong connector since the camper is wired for 120vac. I got everything hooked up and started turning on loads in the camper, after a few minutes the breaker on the generator flipped. I done some more research and found out that each hot terminal on the 4 prong connector can only handle 22 amps, the generator can handle a total of 42-44 amps depending on who you ask. My question is this, is there something I can do to get all of the amperage use out of the 4 prong connector?
 
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Old 08-28-12, 03:34 PM
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You would need to modify the gen so it supplys power from both windings. Its probably easier to buy a new gen with this capability.

You probably seen them. They have a 120v only 120/240v only switch.

Here is what I mean.

http://mayberrys.com/honda/generator/html/120-240.htm
 
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Old 08-28-12, 03:42 PM
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What does the electrical system in the camper look like? Can it take 120/240 split-phase power and use it in a breaker panel?
 
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Old 08-28-12, 05:53 PM
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Nashkat, as far as I know it is not split phase. Lawrosa, could a shop that repairs electric motors perform this work on the motor
 
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Old 08-28-12, 06:13 PM
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I don't think you can modify a 120/240v generator to output full power at 120v. In the honda example in that link, if you try to simply rewire a 120/240v genny with a DPDT switch to swap the coils between series and parallel, you'd have a 240v dead short because the coils are 180 degrees out of phase. The dual voltage genny must have something else going on to synchronize the coil phase in 120v mode.
 
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Old 08-28-12, 06:43 PM
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Lawrosa, could a shop that repairs electric motors perform this work on the motor



Yes. Its easier if you already have 4 wires coming out of the head. I did my own and it will help if you had the schematics. I have no 240 loads so it was beneficial for me.


Not sure the code implications so you should ask the electricians here on that. But mine is done exactly on how they do it with the switch only without the switch..

4 wires coming from windings. If you do not have this and only 3 then IMO its not worth doing. You need to go in and separate the windings then and its a PITA..




Schematic before mod.



After mod.




You want to make sure your wiring is correct. My gen is unbonded. I am bonded when I plug into the home. ( I put a plate over where it says 240 on my panel so anyone will know that the gen is 120 only. Also the 4 prong outlet was changed to a 3 prong 30 amp twist lock)



This is a whole other subject in it own. So now if you use the gen as a stand alone out in the woods with an RV with no ground you will need to discuss this with the electricians here.

Also you would most likely add a 30 amp RV outlet and remove the 4 prong outlet. But now you have to think. Are you using this for your home also?

Possibly it may be best to add the switch in your case. This way you can power your home with the 240 then switch to 120 and add a extra 30 amp rv outlet to power your camper.

If you do not understand what I am saying here then its best get a electrician to do this for you. Preferably a gen/motor place that knows what they are doing.

Whats the make and model of gen you have?
 

Last edited by lawrosa; 08-28-12 at 07:26 PM.
  #7  
Old 08-28-12, 06:46 PM
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Nashkat, as far as I know it is not split phase.
OK. What is the first thing the power goes to inside the camper?
 
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Old 08-28-12, 07:54 PM
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Thanks for this info, I'm going to look at the generator tomorrow and see if this possible. The generator is a 5500 watt 30 amp Briggs and Stratton storm defender. Thanks again for your help
 
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Old 08-28-12, 07:58 PM
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I'm pretty sure the first thing it runs to is the 55 amp converter, the converter runs the 12 volt lights and also houses the breaker panel for the AC appliances
 
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Old 08-28-12, 08:23 PM
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I think this is yours.

http://bsintek.basco.com/BriggsDocum...HXAnfBhU7y.pdf

Also I see it has a 6 pin connector so probably has seperate wires to the windings. Blue, red, black, grey. One green. The 6th is not used.

Here is your manual but you need to write to briggs to get the schematics. Thats how I got mine.

http://bsintek.basco.com/BriggsDocum...FXEnfBhU7y.pdf


Oh wait I just found your schematic. I think your good to go. IMO i would do mine with a switch if I had to do it over. I would have retained the 240 and mounted a rv 120 outlet under the existing panel.

http://bsintek.basco.com/BriggsDocum...kl-79DteBc.pdf

Hope this helps.

I have a schematic of a gen with the switch with all outlets I describe but I cant seem to upload it.
 
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Old 08-28-12, 08:51 PM
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the converter runs the 12 volt lights and also houses the breaker panel for the AC appliances
Is that a 240/120 panel? Does it have two hot buses, each of which powers half of the breakers (like the breaker panel in your house)?

If you aren't sure, you can post a couple of pictures of it, including one with the door open, and enough to let us read any labels. See How To Put Pictures In Your Post.
 
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Old 08-28-12, 09:07 PM
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Nash as far as I know on a 30 amp RV is one leg. The 50 amp RV has two legs.

I believe in all RV's the breaker panel is first. I think the inverter/converters act as automatic transfer switches.

He probably is tripping the breaker because he is trying to use his A/C and he does not have enough generator running from only one winding. Really throws the balance off of the gen too.

Does this help?

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I don't know everything here and may be wrong on some things. Please correct me if I am.

This is just my experience with my gen and getting it ready for home and RV use. Although I do not have the RV yet....LOL
 
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Old 08-28-12, 09:29 PM
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Yes, that clearly shows a single 120V feed. I was just wondering whether that was what the OP has. Most likely he does, but I thought I'd ask.
 

Last edited by Nashkat1; 08-29-12 at 08:42 AM. Reason: typo
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Old 08-29-12, 07:36 AM
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There are errors with the unmodified Coleman diagram. The whites are shown on the wrong sides of the 120 volt receptacles.
 
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Old 08-29-12, 07:56 AM
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There are errors with the unmodified Coleman diagram. The whites are shown on the wrong sides of the 120 volt receptacles.

You mean this one????



The colors do not mean anything. White and black is just what they used. Look at the link for the OP's schematic I found for him. They use 4 different color wires.

I like to use the flashlight analogy like here. Because you see in my mod that I have tied the black and white together...LOL


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utterpower.com
 
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Old 08-29-12, 08:28 AM
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I didn't mean to confuse anyone, but feel if they are going to provide a diagram it should follow normal wiring conventions with the black being shown on the brass.
 
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Old 08-29-12, 10:25 AM
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Makes the people who drew the diagram and approved it look like idiots and can you really trust idiots? That makes the whole diagram questionable.
 
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Old 08-29-12, 04:18 PM
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I didn't mean to confuse anyone, but feel if they are going to provide a diagram it should follow normal wiring conventions with the black being shown on the brass.
I took apart one of those generators last fall, and the colors shown were the colors in the receptacle box. The only color that was conventional was the green/yellow. All of the others were wrong. IIRC, the red and black were neutrals, with the blue and gray being hot.
 
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Old 08-29-12, 04:36 PM
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Well from what I can tell you that is not shown on the schematic, is that thet the blk/wht wires are only from the windings. That is, up to the molex connector. Inside the panel its black, white and green. Wired how a residential home is wired.

So in meaning, white in the panel does not necessarily go to white off the windings.

Hope this makes sense.


Also I did this because I have no 240 loads as stated. I do not have to worry about balancing the loads. I get full amps/wattage from the gen at 120v.

Thats my take on it anyway.
 

Last edited by lawrosa; 08-29-12 at 04:52 PM.
  #20  
Old 08-29-12, 05:58 PM
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Thanks for all of yall's help. I'm going to go with lawrosa's idea, but I'm going to find an electrician who can do it. I would attempt this myself but the generator was 800.00 dollars and my camper was 20,000, so I think I will let a professional handle the wiring. Thanks again for all your help!
 
  #21  
Old 08-29-12, 06:12 PM
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I still dont understand how taking the two coils that are 180 out of phase and putting them in parallel isn't going to create a 240v dead short.
 
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Old 08-29-12, 06:46 PM
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Well in the fist diagram the top the windings are in series. You have two hots, a neutral, and ground.

Each winding is 120v. A generator only makes 120v at each winding period. To get the 240 you take 120 from one and 120 from the other. Separate wattage/amps from each side.


In the next diagram the winding are parallel. They are working together. Remember you still only have 120v but double the amps and watts.

Just one hot, a neutral, and a ground.






The best way to understand is the battery diagram I have shown. Remember when I rewired mine if you look I turned one winding around in a sense by the rewire.


Note this pic shows the battery's but does not show the proper wiring. The battery's should be + to + with this wiring. And get you the 240v


The battery's shown how they are now should be depicted in my modified drawing below this one.




I tried to explain best I could. Possibly someone else can do better then I.
 
  #23  
Old 08-29-12, 06:58 PM
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I agree with Matt - I'm not understanding this.
 
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Old 08-29-12, 07:01 PM
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The winding is going to make power regardless what way its facing. It all how its wired.

Look at my before and after schematic.

I will try to show it better somehow.
 
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Old 08-29-12, 09:02 PM
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I understand what you're going for. And I know they make power regardless of which way they are facing. But the fact that they are 180 degrees out of phase with each other means the waves clash. What you are proposing is no different than trying to connect the two legs of a standard split-phase breaker panel together - You have 240v of potential across them because the legs are 180 degrees out of phase with each other. Connecting them together creates a 240v dead short.

What am I missing?
 
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Old 08-29-12, 09:09 PM
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If anyone cares to read additionally, the link is at the bottom.

( Furd where were you when I needed you...LOL)



8. Windings in Series and Parallel
Many transformers are supplied with two (or more) secondaries. In many cases, the data sheet will indicate that the windings may be connected in parallel or series. For example, a toroidal transformer may be rated at 2 x 25V at 5A (250VA).

With the windings in parallel, the available current is 10A, but only for a single voltage of 25V AC.

Connect the windings in series, and you get 50V at 5A, or by referencing the center tap to earth, the familiar 25-0-25 designation.





Figure 8.1 - Windings in Series and Parallel



There are some rules that apply to winding interconnections - if you break them, you may break your transformer as well. Note the dots on the windings - this is the traditional way to identify the start of a winding, so that the phase may be determined.


Anti-phase wiring will not harm a transformer when wired in series (although the zero volts output for equal windings is somewhat limited in usefulness).

Parallel anti-phase connection will destroy the transformer unless the fuse blows - which it will do mightily. ( See my note below.)

Always use a fuse when testing, as a simple mistake can be rather costly without some form of protection for the transformer and house wiring!



Transformers Part 2 - Beginners' Guide to Electronics


Note: To figure what windings I was working on was as simple as doing a continuity test. White wire were my center taps. Match the black to the same winding and wire away.

I hope this make sense. Quite simple really.
 
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Old 08-29-12, 09:22 PM
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Oh I'm a friggin dunce. I missed that in a generator you have access to both poles of both coils, they are not bound together in a center tap as they are in a breaker panel.. When you connect 1A to 2B, 1B to 2A, the two waves are in sync. 1A to 2A, 1B to 2B gives you the split phase.

Ok.. Got it. Makes sense now.
 
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Old 08-29-12, 09:25 PM
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And you claim you're not an electrician! Got it, and I'll go join Matt in the Dunces' Corner now.
 
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Old 08-29-12, 09:31 PM
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Got a seat all ready for ya!

 
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Old 08-29-12, 09:34 PM
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:settling in:

Yeah, it was easy once we got our heads on straight, wasn't it?

Thanks!
 
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Old 08-29-12, 09:40 PM
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Mike, you didn't need my help. You did an excellent job of explaining.
 
  #32  
Old 08-29-12, 10:02 PM
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LOL, you guys are funny...

I missed that in a generator you have access to both poles of both coils, they are not bound together in a center tap as they are in a breaker panel..
Matt not all generators are created equal. There are very few that offer the center tap with both leads from the windings.


Most have one lead for the center tap, and if you have one of those gens then you have to go into the winding and separate it. A PITA and not worth it.

This is generator buying 101 IMO. This is what I looked for when buying my gen. Coleman's, and Generac XP's have that as far as I know. Not sure who else. But I have not checked in a while and not sure what they are doing now.

And you claim you're not an electrician!

Nope... Just technical school in component repair from 25 years ago, and I really forgot most of it...LOL. Ahhh... the oscilloscope days!!!! Component repair not the same as house wiring...
 
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Old 08-29-12, 11:43 PM
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Ok, I've been trying to work this out on paper to figure out how th OP's genny would have to be wired in order to make it 'switchable' so not to sacrifice the 240v function.. I have something that should work, but then I noticed a problem..

After a disturbingly long time staring at Mike's modified diagram, I need you to explain the theory on how the breakers work in that circuit. The way my brain is reading it, there's either no protection at all on any outlet, or it's still only 20A total. Breakers in series don't sum. Think of it like a 20A 2 pole breaker serving a straight 240V appliance.. You can't get 40A through the appliance, it trips when either leg exceeds 20A. You would need to parallel those breakers to allow 40A to flow - which isn't exactly an ideal way to do it either, especially given the 30A receptacle, but it's better than nothing.
 

Last edited by JerseyMatt; 08-30-12 at 12:05 AM.
  #34  
Old 08-30-12, 12:02 AM
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Does this help Matt?


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-------------------------------------------------
 
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Old 08-30-12, 12:12 AM
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That's basically what I came up with, using a 4PDT switch..

But I'm talking about yours.. Look at your diagram and explain how the breakers do their job wired that way? It looks like each coil bypasses the other coil's breaker, and I can't figure out if the outlets are totally unprotected or only protected at 20A for all.
 
  #36  
Old 08-30-12, 12:16 AM
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Well look at the breakers on the schematic I just posted. They are before the switch... So you tell me?
 
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Old 08-30-12, 12:27 AM
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So basically it's only protecting at the breaker rating. You can't get the full capacity out of it. As I said, breakers in series don't sum.
 
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Old 08-30-12, 12:55 AM
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So basically it's only protecting at the breaker rating.
Yes. But I think the 15 amp breakers in the transfer switch will trip before the gen.


You can't get the full capacity out of it. As I said, breakers in series don't sum.


Full capacity out of what?

 
  #39  
Old 08-30-12, 01:08 AM
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I submit that schematic is wrong. Using a 4PDT switch and another 120 volt CB, with all CBs wired downstream of the switch will allow for double the current when in the 120 volt only position.

The switching of the generator's windings from a 240/120 volt connection to a straight 120 volt connection must be done prior to the output circuit breakers. If the circuit breakers are inserted into the circuit before the voltage selection switch they will have to be in the proper winding output to allow them to be in parallel and then they will protect the individual generator windings.
 
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Old 08-30-12, 01:18 AM
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You know Furd someone sent me that schematic and I am not sure where its from.

It shows two 15 amp breakers there. Odd because that gen shows the 30 amp TT outlet.

Hmmm... Maybe your right.

Using a 4PDT switch and another 120 volt CB, with all CBs wired downstream of the switch will allow for double the current when in the 120 volt only position.
You would need a breaker for each outlet is what you are saying? Like 30 amp for the TT outlet or L14. and 15 or 20 for the duplex?


 
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