Inverter generator with transfer switch

[johnnyV]

Hi there.
I have a 120V firman 4000W inverter generator that has a 30A RV three prong plug. I’ve already confirmed the inverter has a floating neutral and I want to use this inverter with my transfer switch.

I have an adapter that I use to convert the three prong RV plug to a 4 prong twist lock where hot appear to be jumpered. So from the adapter I get 120V from L1 and neutral and L2 and neutral. The inverter then runs into a twist lock inlet that goes into my house and to the transfer switch. All the 10 circuits I have on the transfer switch are single pole so I have no 240v applications. When I power up the generator and plug it into the inlet it immediately trips and shows an overload light. The problem is I have all the loads turned off at the transfer switch so everything is in line mode.

What could be happening?

Here is my gear

Firman 4000W inverter generator model WH03242 link: https://firmanpowerequipment.com/products/wh03242

I’m using this adapter: Parkworld 67867 NEMA TT-30P to L14-30R 1-Piece Adapter, RV 30A TT-30 Male Plug to Generator 30A 4-Prong L14-30 Female Receptacle https://www.amazon.ca/dp/B08F4YQLBX/?tag=atomicindus04-20

Finally I have the Reliance Controls manual transfer switch model CRK310

 

[RPH]

Inverters are funny devices. Plug into at both ends. Turn one light load on. Try starting the generator after doing this.
Most control’s systems on the inverter will look at the output, voltage, current load versus output. Plus the arcing when the do get started may cause an inverter fault to shut the output down. These inverters use either mosfet but more likely igbt’s devices. The control are designed to protect them from damage.

 

[johnnyV]

Inverters are funny devices. Plug into at both ends. Turn one light load on. Try starting the generator after doing this.
Most control’s systems on the inverter will look at the output, voltage, current load versus output. Plus the arcing when the do get started may cause an inverter fault to shut the output down. These inverters use either mosfet but more likely igbt’s devices. The control are designed to protect them from damage.

Ok I will give that a go. That is very strange that it trips at startup as soon as the plug goes in but I will try. So it’s safe to start a generator with a load on it?

Is there any wire modifications I need to do? I presume that adapter I have will do the bridging of the loads but I’m not sure if there is anything else I need to do

 

[RPH]

Light load. Small light bulb. It may very well looking for the initial current feedback for regulation. If the inverter that I used to work on had an open output it would fault with over current alarm and high frequency alarm. Being inverter controls brings another layer of controls. Motor generator regulated by motor speed are much more forgiving than the digital units.

 

[mike93lx]

Ok I will give that a go. That is very strange that it trips at startup as soon as the plug goes in but I will try. So it’s safe to start a generator with a load on it?

Is there any wire modifications I need to do? I presume that adapter I have will do the bridging of the loads but I’m not sure if there is anything else I need to do

I'd be checking all the wiring and connections for a short, especially the adapter you have.

 

[nadogail]

I guess I will continue to deal with engine driven magnets spinning in a basket of wire.
Once I get the engine started speed regulation seems to be pretty basic and easy.

 

[johnnyV]

Thanks all. So here is what I did.
I put a light on the 10-3 coming into the transfer switch from the outside. Connected the light to the black hot first, fired up the generator, all is well reading 125V. Then I did the same with the red hot and same result. Lights work and 125V.

Then I tried to hook up one of the hot leads to one of the hot leads on the transfer switch and left the red one unconnected so its true 125V going in which will power half of my transfer switch. Tried with no load, tripped, tried with small load, tripped. I'm puzzled.

 

[johnnyV]

I guess I will continue to deal with engine driven magnets spinning in a basket of wire.
Once I get the engine started speed regulation seems to be pretty basic and easy.

i dont follow

 

[nadogail]

i dont follow

I only have old school rotary generators, i don’t own any inverter powered equipment.

 

[wyliesdiesels]

Is the transfer switch set to utility or generator and is it hooked up to your panel?

 

[RPH]

Imbalance on the output may very well be a safety function. It works, so that tells you a lot. It’s not happy with the load on the output. Hook both lines up as they should be. Verify connections and wiring. How is the ground handled between inverter and house?

 

[johnnyV]

Is the transfer switch set to utility or generator and is it hooked up to your panel?

its set to utility and yes its hooked to my panel

 

[johnnyV]

Imbalance on the output may very well be a safety function. It works, so that tells you a lot. It’s not happy with the load on the output. Hook both lines up as they should be. Verify connections and wiring. How is the ground handled between inverter and house?

yes when both are hooked up it still trips. The is a floating neutral generator. The ground is bonded to the neutral in the panel

 

[Zeke]

its set to utility and yes its hooked to my panel

yes when both are hooked up it still trips. The is a floating neutral generator. The ground is bonded to the neutral in the panel

I think I see 2 problems.

 

[johnnyV]

I think I see 2 problems.

pls elaborate

 

[Zeke]

Well, I'm not enough of an expert so I thought I'd wait for one of the many electricians who generously share their time and knowledge with us. And I have been frequently wrong or ill informed.

However, shouldn't your trans switch be in the 'generator' position? You make it sound as if your panel is stull energized from the Poco.
2nd, try moving the ground from the genset from the neutral in the panel to the ground. IDK if this is your main panel or a sub. Why that would make a difference in a sub, I can't say. So try running your system w/o the bond and see.

Otherwise I'd have to agree that your wiring is not right. You are using a 3-prong male plug going into a 4-prong wall recept that was designed for 240v. Are you sure you have isolated the L2 so that you are on a single bus? The 3 prong is line, neutral and ground. You should only be using L1, neutral and ground at the wall and on into the panel.

Forget the bonding wire for now or bond it to your system ground via a grounding rod, metal water pipe, etc.

Again, I thought I could see 2 problems. I could be off base on both. But your wiring has to be correct and something isn't, IMHO.

 

[johnnyV]

Well, I'm not enough of an expert so I thought I'd wait for one of the many electricians who generously share their time and knowledge with us. And I have been frequently wrong or ill informed.

However, shouldn't your trans switch be in the 'generator' position? You make it sound as if your panel is stull energized from the Poco.
2nd, try moving the ground from the genset from the neutral in the panel to the ground. IDK if this is your main panel or a sub. Why that would make a difference in a sub, I can't say. So try running your system w/o the bond and see.

Otherwise I'd have to agree that your wiring is not right. You are using a 3-prong male plug going into a 4-prong wall recept that was designed for 240v. Are you sure you have isolated the L2 so that you are on a single bus? The 3 prong is line, neutral and ground. You should only be using L1, neutral and ground at the wall and on into the panel.

Forget the bonding wire for now or bond it to your system ground via a grounding rod, metal water pipe, etc.

Again, I thought I could see 2 problems. I could be off base on both. But your wiring has to be correct and something isn't, IMHO.

Thanks for the reply. This is going directly into my main panel where the neural and ground are bonded. It should be in gen position when I’m ready to turn on the circuits. It won’t even run in line mode. Even in gen it does the same thing. Most if not all sources and existing adapters are bridges meaning it will deliver 120v on each leg and should work fine so long as I don’t have any branch circuits or 240v applications. I’ve got a larger 10kw generator on order with the 120/240v outlet but to be honest it should make no difference.

Firman sent me instructions on resetting the ECM as a last resort before I return the generator. If that doesn’t work I guess it’s gotta go back

 

[wyliesdiesels]

Well, I'm not enough of an expert so I thought I'd wait for one of the many electricians who generously share their time and knowledge with us. And I have been frequently wrong or ill informed.

However, shouldn't your trans switch be in the 'generator' position? You make it sound as if your panel is stull energized from the Poco.

2nd, try moving the ground from the genset from the neutral in the panel to the ground. IDK if this is your main panel or a sub. Why that would make a difference in a sub, I can't say. So try running your system w/o the bond and see.

Otherwise I'd have to agree that your wiring is not right. You are using a 3-prong male plug going into a 4-prong wall recept that was designed for 240v. Are you sure you have isolated the L2 so that you are on a single bus? The 3 prong is line, neutral and ground. You should only be using L1, neutral and ground at the wall and on into the panel.

Forget the bonding wire for now or bond it to your system ground via a grounding rod, metal water pipe, etc.

Again, I thought I could see 2 problems. I could be off base on both. But your wiring has to be correct and something isn't, IMHO.

not quite sure what youre saying here but if you remove the neutral to grnd bond in the main panel, youve created a dangerous situation where breakers wont trip upon fault current energizing metallic pathways that shouldnt be energized

there should only be 1 neutral to grnd bond, so the floating neutral on the generator is fine...

 

[Zeke]

Wait a minute. You don't have 2 phases. Not that I can tell from what you're posting and the plug you're using at the generator. It's a single phase 120v, 4000w (convert that to amps if you wish, most of these are rated at surge, so not really 4000w).

You have one hot leg and you can tie into one side of your main thru the transfer switch. There is a need to disconnect the other leg from the SE. You can't have one side on the grid and the other on your genset.

 

[Zeke]

Wylie, apparently I wasn't clear. That could be a problem with me. I didn't say to modify anything in the panel. And I doubted in my post that the bonding would make a difference.

Glad you're on board now. It will get sorted. If I brought some info out of the OP, then I helped in a tiny way.

To make myself clear, the OP has to use a 2 pole TS and nothing goes to one leg of the gen feed side when switched to Generator. IF this isn't right then I didn't do it right. I have a 3500w single phase 120v dual fuel genset. It goes to a sub that has house basics, all 120v mostly 15A circuits and it doesn't even pick up all of those because they are divided across the busses. No DP breakers in that box.

 

[wyliesdiesels]

Wylie, apparently I wasn't clear. That could be a problem with me. I didn't say to modify anything in the panel. And I doubted in my post that the bonding would make a difference.

Glad you're on board now. It will get sorted. If I brought some info out of the OP, then I helped in a tiny way.

To make myself clear, the OP has to use a 2 pole TS and nothing goes to one leg of the gen feed side when switched to Generator. IF this isn't right then I didn't do it right. I have a 3500w single phase 120v dual fuel genset. It goes to a sub that has house basics, all 120v mostly 15A circuits and it doesn't even pick up all of those because they are divided across the busses. No DP breakers in that box.

he would have to have a 2 pole TS because the other source is the PoCo.... and he does..... the reliance unit is 2 pole

he is bridging the 2 hots in the TS with that TT-30 to 14-30 adapter. that shouldnt cause any shorts.

 

[Zeke]

Ok, I see it now. There's still a problem. My experience says most of the time it's user error.

And I didn't have to do any bridging. I used a 10/2 SO cord between the genset and the wall plug. Obviously one prong of the wall plug gets no current and is not used. This is where I might be confused. Is there a need for a bridge?

The way I'm set up is that if I get a 120/240 generator, all I need is a new cord, a 10/3. But I'm not into trying to use that much fuel during a blackout. Fridge, freezer and a few lights and we will be comfortable enough to wait it out.

 

[wyliesdiesels]

Ok, I see it now. There's still a problem. My experience says most of the time it's user error.

And I didn't have to do any bridging. I used a 10/2 SO cord between the genset and the wall plug. Obviously one prong of the wall plug gets no current and is not used. This is where I might be confused. Is there a need for a bridge?

The way I'm set up is that if I get a 120/240 generator, all I need is a new cord, a 10/3. But I'm not into trying to use that much fuel during a blackout. Fridge, freezer and a few lights and we will be comfortable enough to wait it out.

yes so you can power both busses in the TS.... its a 120/240v TS

Otherwise if you do it like your setup, then half the breakers in the in the TS wont work on gen power...

Top-Quality Transfer Switch Kit | Reliance Controls

We provide top-quality generator transfer and safety switch, generator transfer panel, power transfer switch for generator, and house generator transfer switch.

www.reliancecontrols.com

 

[johnnyV]

yes so you can power both busses in the TS.... its a 120/240v TS

Otherwise if you do it like your setup, then half the breakers in the in the TS wont work on gen power...

Top-Quality Transfer Switch Kit | Reliance Controls

We provide top-quality generator transfer and safety switch, generator transfer panel, power transfer switch for generator, and house generator transfer switch.

www.reliancecontrols.com

I guess this is my confusion right now. The RV plug is connected to a bridged adapter which produces a hot on both the red and black with 120V. There is no load on the switch, all breakers are off and everything in line position. It still trips as soon as I plug it in. However as mentioned before each individual hot (red and black) can power a light bulb in the switch no problem

 

[AntonLargiader]

Can you confirm a few things?

1) The adapter takes L1/N/G* from the TT30 and turns it into L1/L1/N/G in the 14-30, right?

2) With the adapter connected to the generator you don't get the fault. And it seems you have a 14-30 extension cord that plugs into the adapter at one end and the xfer switch inlet on the other, right? And having both of those connected to the generator doesn't cause a problem?

3) You powered a test lamp at the end of the extension cord from each hot to neutral (and both hots are actually the same hot, one leg of the generator). But when you plug the end of the cord into your xfer switch inlet, even with no loads at all connected to its L1 or L2, you get the trip?

*EDIT: forgot the TT30 is not 240V. Reading the details now in the manual.

 

[Zeke]

Way beyond my pay grade here, but is there some voltage leakage that affects the neutral?
I've never heard of anyone using L1 and across a split phase panel. But I'm not out there everyday digging around in panels. Actually, I'm retired. But that doesn't keep me from wanting to know more.

 

[AntonLargiader]

I'm wondering if connecting the ground to the neutral through the panel is what is kicking the generator out. Seems that a floating neutral should be intended to work exactly that way, but there could be an issue. Easy to test.

Beyond that, I would do basic troubleshooting to see if the xfer switch is actually being the totally open circuit that the generator expects it to be. With all of the switches set to line, is there continuity between L1 and N, or between L2 and N, at the inlet? If so, then maybe the switch is wired incorrectly. Can you power the inlet with something other than the generator, that has overload protection? See if it trips.

 

[Zeke]

I'm wondering if connecting the ground to the neutral through the panel is what is kicking the generator out. Seems that a floating neutral should be intended to work exactly that way, but there could be an issue. Easy to test.

Beyond that, I would do basic troubleshooting to see if the xfer switch is actually being the totally open circuit that the generator expects it to be. With all of the switches set to line, is there continuity between L1 and N, or between L2 and N, at the inlet? If so, then maybe the switch is wired incorrectly. Can you power the inlet with something other than the generator, that has overload protection? See if it trips.

I kinda touched on that ground/neutral idea and then threw that theory out the door. I think Wylie agreed. Nevertheless, in the sprit of testing. I suggested temporarily not using that bond wire. Ya never know. My genset lives in a plastic weatherproof enclosure not likely to come into contact with anything including the concrete below. It's actually a deck box. So I've never bonded it. But there is a bonded gas line right there that I thought if I ever get around to it, I'd get the device to make it tri fuel.