Wyatt-S
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Re: 3000W Chinese Gensets Info.
alvinc wrote: Circuit breakers (or fuses) are used to protect the wiring from over current situations. It's not clear to me that a single winding in the generator can support 30 amps. Willing to be wrong.....tell me why. You are not wrong, kind of. The maximum current depends on where you plug into. If you connect to the 120V standard outlet (brown to red) then the maximum current is that supported by the brown CB since the blue CB is not in that circuit. If you connect to the brown-blue at the 30A outlet then the current is limited to whichever breaker trips first since both breakers are in series on that circuit, although, since the CB's are physically connected to each other both would trip anyway. In any case you would never pull more current than the original factory design allowed for at 120V. Agree? Where I do agree is that if one winding opens then all the load will come from the other winding. Since the circuit is still protected as per the original factory wiring (no more current can flow through the CB's than in the original config) I would expect (hope) that a single winding would not open prior to the breaker tripping. When I tested the Gen set originally, I purposely pulled a load to see where the breaker would trip. The breakers tripped at well above 30 amps but that was because the voltage dropped precipitously and the amperage increased very quickly. I would imagine the same thing would happen if one winding would open as in your scenario. It would be better to protect each winding with a smaller breaker but that would no longer be a simple re-wire. I guess that a simpler approach, and one that I am considering, would be to fuse the jumper between red and brown and the brown Gen lead prior to the post at 20 amps each. That way if one winding went open the most you could pull from the other would be 20 amps. A simple car fuse on each side would suffice. But then I think, if one winding is gone, I really need a new Gen! To summarize: The rewiring I drew does not ever permit a greater current flow from any one winding than the original wiring did. IMO, I am not sure it's worth the bother. I welcome your comments!336Views0likes0CommentsRe: 3000W Chinese Gensets Info.
wildnfree and pup: You are both right, but why cut wires and move gen leads. I meant to keep this simple. It's confusing enough as it is. That is why I made a color coded schematic, basically, the old "KISS" concept. You can move the red gen lead to the brown post or cut the red panel lead and attach it to the brown post (that makes it just a jumper anyway) and re-attach what's left of the panel red to the blue post but now you have a shorter red lead to work with without a terminal on the end. No need to do any of that! Moving the red gen winding lead to the brown post makes sense if you do not want to place a jumper. But, placing a short jumper keeps all the gen leads in their original place making it a little bit easier to go back if you wanted to. Electrically, it makes no difference, I would choose whichever method seems easier to you, but I would not cut the red panel lead simply to reattach it.555Views0likes0CommentsRe: 3000W Chinese Gensets Info.
nm_desert_rat said: I re-wired explicitly per your drawing, and also using another suggestion, moving the red lead to the brown lead from the gen, thus eliminating the jumper. The gen voltmeter read ~220V before and ~110V after the mods, so I'm pretty confident that I did it right. I'll restore it to factory config and measure voltages again. Desert, There need to be two bridges at the gen head in order to wire in parallel. My schematic shows one bridge and the other bridge is placed by moving the red panel lead (since it is connected to the white panel lead in the sleeve) effectively placing two bridges. one across the red-brown gen leads and one across the blue- white gen leads. One brige will only allow one coil at any given time.555Views0likes0CommentsRe: 3000W Chinese Gensets Info.
NM_Desert_Rat wrote: Wyatt-S, allpraisebob, et al: I rewired my PP3500 per Wyatt-S's drawing on his profile page, without any noticeable difference in performance. Here are the symptoms (same symptoms before and after mod): Desert, I had those same symptoms prior to re-wiring but have not had that since. Are you sure you followed the instructions precisely? If you did not, then you may still be pulling current from only one coil. You have to bridge the red and brown coil leads and move the red panel lead to the blue Gen lead. This should put the coils in parallel and you should no longer have the symptoms you describe unless you have an open coil on the Gen. The easiest way to test for this is to put the Gen back to factory wiring and test for 240 volts. If you have 220-240V then both coils are fine if you have 0 volts then one coil is open. There are other methods but this one is the simplest. You might have overloaded the primary coil when you had all the RV appliances on, prior to rewiring. I tried that and recall that the voltage was dropping significantly. Did not do that too long for fear of frying one of the coils.555Views0likes0CommentsRe: 3000W Chinese Gensets Info.
I did this mod yesterday. The voltage never dropped below 112 at full load (28 amps) but the breaker will trip if I pull a sustained load above the 28 amps. This is with the RV connected to the normal 120V outlet. BTW MrWizard, I was thinking the same thing. When I originally tested the Gen with the factory config the breaker did not trip until about the same amperage although the voltage at that point was below 100V. You'd think the breakers would trip at a lower amperage than that, but they never did. If anything, the CB's should be tripping with the rewired config since all the current is flowing through a single CB. Testing shows the CB does not trip until 28 Amps at which point you can hear the gen is under heavy load. I ran it for an hour this way, (pulling about 24.2 amps and 112.8 Volts, basically just over 2700 watts). CB never tripped. In any case, this should not be a safety hazard since the worst that should happen is for the CB to trip below full load. At which point I would consider wiring the CB's in parallel or changing them out for a higher rated one. To wire the CB's in paralell you would simply have to move one more wire. The blue panel wire would have to be moved to the red gen wire. Then the NEMA outlet would have one CB on the blue wire and one CB on the brown wire, both on the same phase. Then either bridge the wires at the outlet (requires opening the panel) or bridge them at the male plug. I did not like that option since it effectively paralells the CB's and they are not tripping the way my re-wired schematic shows. I would rather have one CB trip at too little current rather than two in paralell at too much. Specially when testing! However, the CB is not tripping prematurely, so there is no need to go to the extra length. Single CB is safer and if it does not trip at too little current, then my preference is to leave it that way. The schematic is posted in my profile for those that wish to view it.555Views0likes0CommentsRe: 3000W Chinese Gensets Info.
presp- My goal was to come up with the simplest, yet safe way, to rewire this gen so others, who may not be mecahnically inclined, could do it as well. I think this design accomplishes that. Both outlets (depending on how you wire your 4 prong plug)are protected by a single CB rated at 25 amps but actually trips at a sustained 28 amps (the full rated power of this gen set) and breaker two should (have not tested) trip at about 13A sustained. In my testing, CB1 did not trip at a surge load of 32 amps but did trip at a sustained 28A. I think this effectively protects the gen set from overload. The wiring can easily be desined to put the CB's in parallel, but I think that is dangerous since the current would be split and I don't know when they would trip. I would imagine that CB two would still protect the circuits, but I just don't like paralell CB's.297Views0likes0CommentsRe: 3000W Chinese Gensets Info.
This is the re-wiring I was referring to in my previous post. The + and - signs do not depict actual polarity, merely coil phases for ID. As you can see voltage is supplied to both outlets of the Powerpro 3500 at 120 with the coils in parallel. The meter will read the correct voltage and the breakers remain wired in series with the outlets. A very simple rewire that gets the job done. Have not done it yet, will post results when I do. Comments are welcome. The schematic is posted in "my profile" for those interested.297Views0likes0CommentsRe: 3000W Chinese Gensets Info.
Allpraisebob wrote: Yikes! If you follow your own instructions, Wyatt-S, you better hope the engine refuses to start under the tremendous load it'll be looking at when you pull on the rope! This is because your modification connects the two windings so that their outputs oppose each other, not add together, which is even more abusive than short-circuiting them! This is why I put dots on the coils in my schematic, btw; what they indicate is the relative phasing of the winding. That is to say, the dot ends of all windings will be at the same voltage at any given point in time. Another key thing that you missed is that the RED and WHITE wires are spliced together inside of the rubber sleeve connecting the generator head to the front panel. This splice needs to be broken regardless of where you parallel the coils together. I've never heard the term "oppose" used in power sources. They can either be wired in parallel, in series or shorted. Full load is experienced when the coils are shorted not "opposed". By bridging the red and brown together and moving the red panel wire (which is attached to the white panel wire) to the blue you are bridging the coils in phase, ie, blue-white and red-brown. The reason the red and white do not need to be opened in the sleeve is because I am using them to bridge the blue and white gen leads. The schematic I've drawn would illustrate this better but I don't know how to post it. That's where I was asking for help, not on the re-wiring.355Views0likes0CommentsRe: 3000W Chinese Gensets Info.
I am planning on re-wiring a powerpro 3500 I bought locally a couple of days ago. I was looking at the schematics and it seems, that if all you want is to have both coils in parallel to provide more amperage at 120V, then all you have to do is the following: 1. Remove the red wire coming from the panel off of the red wire coming from the coils and add it to the blue wire coming from the coils. 2. Bridge the brown and red wires at the Gen head. No need to open the panel, the above can be done right at the Gen head. Very easy! I created a diagram to show the changes, but since this is the first time I post to a forum like this I am not sure how to insert it. Any help would be appreciated.368Views0likes0Comments
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