Help solve my electrical mystery!

[Dr4Film]

I suspect that the relay for the generator in your transfer switch is faulty. Possibly it is not locking in tight and is fluttering causing your inverter to take over.

For $140 you can replace the transfer switch with a high quality one.

ESCO LPTBRD 50 amp is the one should purchase.

LYGHT POWER LPT50BRD

Just my opinion. I am not a professional electrician.

Dr4Film ----- Richard

[PDR John]

I would try bypassing the wire from the genny to the transfer switch.

That would eliminate a lot of wire that snakes around a lot of edges.

Plus you said the genny did not fluctuate when it was disconnected from the coach.

Shore power to transfer switch fine- transfer switch to inverter fine- inverter to coach fine


genny fine- genny to transfer switch not fine, which narrows it down to transfer switch or wiring.

[ohhwell]

Well, My initial thought is the transfer switch but I have one side thought / question. You mentioned that there is no voltage drop when running the generator is isolated. I just want to confirm that you know this to be 100%. You had said they tested it on a load at the Cummins shop. Do you know for sure that they monitored the voltage as it was running? I would have to assume they did but want to make sure they didn't just run your AC or something and assume that because it did not cycle, there was no slump.

Can you unplug the inverter/charger and bypass the inverter transfer switch and see if everything is OK? I can't get over thinking that it is simply the transfer switch.

[JGrosman]

Greetings Rufuss; When the AC starts it will pull lots of power and then drop to a run level. Do not let that little drop fool you. It is just momentary and the voltage will drop but come back up. There is nothing wrong with 106-109 voltage if your air is on and you try to also run a coffee pot or other high amp object. Remember you might also have on a electric water heater that pulls current. 17 amps for AC and 10 amps for water heater and 6 for refrigerator plus anything else you have on might be a overload on the generator. If it does not come back up then your compressor might be on the way out and your generator can not handle the load. If you should hear a click when it tries to start then that is the breaker in the AC unit but then the AC will not work. In your coach not all outlets are connected to the inverter. If some outlets do not work then it is not on the inverter. Do not let it worry you. Your air does not work on the inverter! That would be too much current for the batteries. So let’s rule out the inverter and any plugs connected to it. Let’s look at this from step one to end. You say that it only happens when on the generator so I will rule out the power cord. I am going to assume that you know how to use a volt meter. It does not matter what type. In your transfer switch box put your meter on volts AC and put one lead on the white lead on the wire coming out the top of the box. Put the other lead on either the black wire or the red wire. Turn on the generator and run the AC. If you do not see the problem there then the next place to check is the fuse panel. You have a 50 amp service and that means the fuse panel is really two fuse boxes and has both hot leads in the box . The generator only produces 120 volts and both hot leads are connected to one lead. Put one lead of your meter on the white wire coming into the panel from the transfer box. Put the other lead on the black or red wire and turn on the air. If you do not see a problem there then we can rule out from there to the generator. Just to rule out the fuses remove the wire to the black or red lead and move it to the fuse that goes to the air that is giving you the problem. If it is ok there then we can rule out from there to the generator. If your coach has a power management system then you need to connect the volt meter to the connector after the power management system that goes to the AC. If you see the power drop out then there is your problem. The power management has a relay in it to turn off the AC if you have too much load elsewhere in the coach. It may be that relay. If the power is ok there then you need to check the power at the AC. That is all the place you can check. Wires in the coach are very, very, very seldom are the problem. After that I assume you have a ghost.

[Bfmorgan]

It will depend on the model of inverter/charger but they also have a transfer switch. From your description, the problem only happens when on generator power and the inverter is detecting a drop in voltage and tries to transfer from incoming AC to inverter supplied AC.

So what happens if you turn off the inverter and just let the generator run?
What happens if the inverter is off, the generator is on, and you turn on the AC?

[wa8yxm]

YOu said LIGHTS flicker and this means no A/C.....

Lights in a motor home are normally 12 volt. A/C is 120 volt. This has me confused.

[Bfmorgan]

Originally Posted by wa8yxm

YOu said LIGHTS flicker and this means no A/C.....

Lights in a motor home are normally 12 volt. A/C is 120 volt. This has me confused.

It's why I asked all of the questions......The generator may be sagging, but that indicates a large load. Maybe? Still doesn't explain why the lights which are on DC would be flickering. I was trying to separate the cause and the effect.

[Dr4Film]

All of the lights are generally 12 VDC powered. They are powered from the house battery bank which is kept charged by the charging circuit of the combination inverter/charger. In this case the generator is supplying power to the charger to drive the 12 VDC lights.

Dr4Film ----- Richard

[sirpurrcival]

I think I would consider bypassing the transfer switch. Run the genset and conclusively remove or confirm whether it is at issue. If it isn't, then I might be inclined to see what you can do in terms of hooking up a portable genset in place of yours for testing purposes. A process of elimination but at some point you will twig to it. My money is on the transfer switch.

[RufussSewell]

Originally Posted by wa8yxm

YOu said LIGHTS flicker and this means no A/C.....

Lights in a motor home are normally 12 volt. A/C is 120 volt. This has me confused.

There are several 12v lights and they are always fine. But there are also several 120v lights that only run on inverter/gen/shore, those are the ones that flicker.

[Old Bounder]

Swap the inputs to the transfer switch from shore power with those from the generator. If the problem switches to shore power, then the switch is the problem.

[terry735001]

Originally Posted by loulong

Swap the inputs to the transfer switch from shore power with those from the generator. If the problem switches to shore power, then the switch is the problem.

stop stop

make sure your neutral to ground fault is all setup up right befor swopping wiring round


gen and inverter have a auto neutral to ground make sure you under stand this system or you WELL get a fire

with that said

i had a 15K honda gas gen set that did what your saying every 5 mins or so its was like a very high load would come on and it would pull the gen down ... at the end of the day i found it was the 220 ac side of the gen going bad

the inverter on yours is kicking in as it has a safety when it see the 110ac getting to low

the 2ed thing to think of is under the shower of my RV all the wiring was ran in the floor and they used wire nuts well one of them was not installed all that good pull a high load and it would get hot and play games on the system up and down


3 some thing to think about most transfer switch have 3 inputs one for gen one for inverter and one for land power i only see 2 inputs on your system ??? is you inverter and gen on the same input wired as one system

if so you really should look in to that as the transfer switch should pick what input it wants and not have the inverter trying to push power in to a gen set and the RV and then looping back in to the inverter to give power to it .. i would make sure you dont have alot of looping going on here

if you do have a 2 input transfer switch then i would guess your power from the gen gos right in to the inverter only and out the inverter to the transfer switch if that is so i would guess some thing is up with the wring from the gen to the inverter and if some one a fix a plug some where to wire it in to the system in the RV some where then thats your loop and why things are going nuts

did you do any update like that in the past
did your RV come with the inverter install or was it installed latter
did you want more plugs to work on the inverter and wire them to do so ... well make the loop there

is the gen set output and inverter output wired in to the same input on the transfer switch if so theres your err and needs it Y off or a 3input transfer switch
the Y off is where one leg on the inverter is on land power side and one leg on gen side for 2 input transfer switchs i would look this up to make sure yours is this was as when testing some one could have moved this wire

they keep thinking the inverter is bad so i am thinking bad wiring form gen to inverter or one above

and make sure your auto neutral to ground is right alot of ppl do not under stand this and errs are made

[Dr4Film]

Originally Posted by terry735001

stop stop

3 some thing to think about most transfer switch have 3 inputs one for gen one for inverter and one for land power i only see 2 inputs on your system ??? is you inverter and gen on the same input wired as one system

Sorry, but that statement is NOT true.

Most transfer switches only have two inputs and one output.

There are transfer switches that you can purchase with three inputs but I think if you took a poll as to who had what, you would find that most RV's have only two inputs, shore and generator.

Dr4Film ----- Richard

[terry735001]

Originally Posted by Dr4Film

Sorry, but that statement is NOT true.

Most transfer switches only have two inputs and one output.

There are transfer switches that you can purchase with three inputs but I think if you took a poll as to who had what, you would find that most RV's have only two inputs, shore and generator.

Dr4Film ----- Richard

i am sorry are you thinking that you if only see gen input and home power input on your transfer switches that it is only a 2 input unit .or that you only see 2 auto switches installed in the box... no really i am asking this / asking you ... this is how errs are made miss info and if i am wrong i need to know and if you are you need to know as this is what starts fires and costs money


the Y off i am talking about inverter input is one wire to to switches A and one wire to switche B so in doing so your inverter has a wired from each side going to gen and power in with that the auto switches can see power from 3 way

a open land ... power comes in for shore power......... power comess in
b closed gen .. no power

a closed land .. no power
b open gen ...............................................pow er comes in

a closed power from one side of inverter in .....power comes in
b closed power from one side of inverter in .....power comes in

most transfer switches run off there own ECM if you have this it is most likely your transfer switches can see the 3 inputs and your transfer switches is a 3 input unit

if you have a older transfer switches where the switches them self run the transfer switches then most likely it is not a smart unit and is 2 input only

here is what happens most ppl want to charger there house battery's from the inverter why gen is running so gen is ran to the input of inverter and inverter is ran to the gen input on transfer switches but you still want to do the same thing on land power so you need a smart inverter so the inverter and see what input it wants to use

latter down the road its time for a new inverter and some one dos not under stand or dos not install a 2 input inverter wiring gets played with and you get the loop we talked about and the inverter is now has its
gen out to both the inverter and the transfer switches the inverter trys so hard to keep the load at 110ac but the gen is going the same thing but lower over RPM after the up and down game the inverter keeps going from power mode to charge mood


look at any PDF of any transfer switches 30 amp or 50 amp where you want to install a
gen
inverter
home power
......as a stand along and you well see

in my pic you can see it would be setup B and really dos not really show the wiring
i need to find a good PDF file of what i am talking about and every thing well fall in to place i well start looking tonight
and you can see the small ECM in my unit

PS i think the units your thinking of are the high $ units where they add a lug that says put wire here


to cut cost they just have you stake wiring under one lug and not label it well but in the PDF