Offgrid Genset Transfer switch

[sodamo]

We have been totally offgrid since 2005. Several systems, several upgrades.
Our current house system is pretty robust:
Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280w & 16 Phono 250w in 48 volt array (fixed) 14080w
12 Hyundai 365w (4380) 18460w total
Radian Inverters GG8048A/GS4048A w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
15 SimpliPhi 3.8 (57kw) (1125 AH)
14Kw Kohler 14RESA (Propane)
Autostrart

Charging Only
2FX3048T Inverters (no ac output)
Hub 10.3
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
EG4 Chargeverter
10Kw MEP 803a Military gen (diesel)
Honda EU7000i (gas)
Autostart

Starlink w Eero Pro 6e network for OpticsRE

My upgrades have not been kept up todate as far as geneset transfer switching
I hope to rectify that and document a bit in this thread if anyone cares to follow and/or comment.

 

[sodamo]

I have a starting design for my new transfer switch.
Goal is to run 1 or 2 gensets from either system.
Yes, I can do so now requires manual control and rewiring of autostart. Goal is the select via switches. Each system. Controls when it runs according to either battery voltage, State of Charge, or Manual -that won’t change other than possibly tweaking settings.

These items on order:

Amazon.com

Amazon.com

Above item are comparable but couldn’t decide so getting both.

Amazon.com

Amazon.com

Amazon.com

Configuration:

 

[sodamo]

While I have received some of the items, not enough for placement. Does look like all will nicely. Still missing Nilight switches and FX breaker box.

 

[Kyle_in_Tex]

Watching!

 

[WinterDeere]

Tangent: For those of you guys running multiple gensets, how do you syncronize them before switching both online? I imagine that just letting the two run side by side with a voltmeter between them might leave the opportunity for differential voltage to drop to zero every once in awhile, due to slight differences in operating RPM, and that you could close a switch between them at that time to lock them in. Once switched together, they should stay in phase.

If one is substantially bigger than the other, I'd guess this could work well, the smaller one will follow. If similarly-sized, I see an opportunity for oscillation.

 

[part-time-Farmer-NC]

WOW. Fascinating topic. I think about an off grid solution from time to time but where I am I don't have the reason to pursue it. One day thought...

Also see you are from my birth state, former military brat. Ft Tripler. We lived there the first 3-4 yrs of life for me and my little sister.

 

[90cummins]

I think we will be learning something here.
I’ll be watching!

90cummins

 

[sodamo]

Tangent: For those of you guys running multiple gensets, how do you syncronize them before switching both online? I imagine that just letting the two run side by side with a voltmeter between them might leave the opportunity for differential voltage to drop to zero every once in awhile, due to slight differences in operating RPM, and that you could close a switch between them at that time to lock them in. Once switched together, they should stay in phase.

If one is substantially bigger than the other, I'd guess this could work well, the smaller one will follow. If similarly-sized, I see an opportunity for oscillation.

Fear not.
I don’t. Have 2 generators powering same charger would be a problem I suspect and will be managed via the transfer breakers- on/off, off/on.
The generators power a DC charge source. My offgrid power is designed to accept multiple DC charging. Think solar powered charge controllers running same time as generator powered DC chargers. Technically I could run my 3 charging sources simultaneously, but I’d have to be mindful from battery standpoint.

I think we will be learning something here.
I’ll be watching!

90cummins

Me too.

Actually I do have 1 issued not resolved. Relays always puzzling to me. My current setup has each generator wired to it’s own relay and everything switched manually. I have a DPDT relay pictured, but not sure if that will work. Will be playing with configuration once I receive the switches.

 

[sodamo]

I was stationed on Oahu 77-81. Wife and I moved here in 2005. Don’t expect to need to pack for next move, simply scatchermy ashes in the dog cemetery.

 

[WinterDeere]

Fear not.
I don’t. Have 2 generators powering same charger would be a problem I suspect and will be managed via the transfer breakers- on/off, off/on.

Cool. I do believe it would be possible to link two generators, heck this is what my FIL spent his career on, as GM of a few power plants. It requires synchronization before switching them together, and probably careful management arrangement of which of the pair controls the system speed, as two governors with similar time constants on similarly-sized generators are almost sure to oscillate against each other.

Long story short, I think it's very do-able, but maybe not worth the time and complexity for any home-based system.

 

[sodamo]

WinterDeere

Doable I’m sure. I actually have 3 individual AC inverters and they are managed via software. My previous system had 4 120v inverters and the system was smart enough to operate safely as normal 120/240. But as for the gensets, that’s a potential headache I’ll avoid.

 

[ponytug]

@sodamo synchronizing gensets prior to transferring the loads has been done lots of ways. The "old fashioned way" is three light bulbs, and a transfer switch or relay. However, that's just for transfer of power.

There are fairly readily available surplus synchronization switches, and that would be my recommendation.

If you want to run two generators, especially two different types or capacity generators, it requires specialized control wiring to ensure that the load is shared equitably and the frequency is kept constant. To do that you need to get pretty deep into electronics, power generation, and control theory. That's not exactly home brew in my book.

Personally, I would rather have the power drop for a few seconds while I flipped a switch rather than have over voltage / over power event from a botched synchronization. That would be very pricey. I don't maintain critical medical loads or radar that require always on power...

All the best,

Peter

 

[hayden]

Just to be sure I'm clear on your power system, and what you are trying to accomplish...

The FX inverters and EG4 are for charging only. So they have AC input only when powered by one of the generators, and the FXs do not have their inverter output's connected to anything. Is that right?

And your goal is to be able to power either the Radian inverters, or the FX+EG4 from either of the 3 different generators?

How do you want it to behave? Gen start triggered off low battery SOC? When that triggers, do you want a generator to start and connect to each of the charger groups? Or just one, and in what priority order? Or should it rotate through them so they both get exercised?

And what about the generators? Always try to start two of the three? Start based on some priority order, or rotate through them so they all get exercised?

I built a somewhat similar system with two generators. When the batteries drop below 25% SOC, one of two generators starts, warms up, then the AC connects to the inverters/chargers. Either generator can be enabled or disabled, and if both are enabled, one always takes priority running and the other only starts if the first fails.

AC power switching is done using industrial contactors, and it's all controlled by a PLC with custom programming. It took a little work to create it all, but it works great.

 

[sodamo]

Hayden, good understanding.
The Outbacks have Automatic Generator Support built into the Mate module and I can set priorities by Voltage ( 24 hour, 2 hour, 2 minute) or by SOC. Yes, want either to have choice of 2 gensets (manual choice) and my ability to set priority of system via Mate.while they share common battery knowledge, Mate control is separate. Only need to run1 at a time. A bit tricky in that LifePO battery voltage is rather flat. I also have the advantage to control via wifi from anywhere I have internet. Handy when traveling as I can monitor and notify housesitter if need be.

Genesets are propane (house tank), diesel, (10g? tank), gas (5g tank. I could chose by fuel, but all hover around $5/g. Been tempted but never figured cost to run. My system is robust enough that the $ are less concern than my motivation. Of course the propane is auto filled and I usually have diesel and gas on hand.

 

[geteh]

We have been totally offgrid since 2005. Several systems, several upgrades.
Our current house system is pretty robust:
Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280w & 16 Phono 250w in 48 volt array (fixed) 14080w
12 Hyundai 365w (4380) 18460w total
Radian Inverters GG8048A/GS4048A w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
15 SimpliPhi 3.8 (57kw) (1125 AH)
14Kw Kohler 14RESA (Propane)
Autostrart

Charging Only
2FX3048T Inverters (no ac output)
Hub 10.3
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
EG4 Chargeverter
10Kw MEP 803a Military gen (diesel)
Honda EU7000i (gas)
Autostart

Starlink w Eero Pro 6e network for OpticsRE
capcut old version
My upgrades have not been kept up todate as far as geneset transfer switching
I hope to rectify that and document a bit in this thread if anyone cares to follow and/or comment.

I have a 1 Victron MultiPlus 48/5000/70 inverter charger 230 volt (not a MultiPlus 2) passing through a Victron Autotransformer and connected to a main electric panel at 110vt on each side and neutral to the neutral bar in the main panel. We now have a new diesel generator 240 volt floating neutral. I would like to power the main electrical panel through a Blue Seas AC Rotary switch 2 sources to 1 (Main electric panel), 2 position and off 65amp 240volt. The main panel is grounded to earth via large copper Rod. Generator to feed 2 hots and neutral to the panel via switch. Question #1. to keep both sources from having any issue with back feeding through the neutral Gen system and solar system could I switch neutrals in the Rotary switch for both systems and connect neutral to the grounding bar in the main panel? Since we use either the generator which is 12.5kw for big load usage including charging solar batteries through the main panel when required or we go through the solar system via the AC rotary switch and to the panel which is maxed at 5000kw. Never at the same time. Question #2 what would be the best solution for connecting these power sources? We are located on a remote Western Caribbean Island with no grid power so we are the power company.
The original installer has grounded the Solar Autotransformer, Inverter/ Charger and PV breaker panel together at a bar and then to a seperate ground rod which is approx 11' from the main Panel Grounding rod. Suggestions and Advice is greatly appreciated.

 

[hayden]

I have a 1 Victron MultiPlus 48/5000/70 inverter charger 230 volt (not a MultiPlus 2) passing through a Victron Autotransformer and connected to a main electric panel at 110vt on each side and neutral to the neutral bar in the main panel. We now have a new diesel generator 240 volt floating neutral. I would like to power the main electrical panel through a Blue Seas AC Rotary switch 2 sources to 1 (Main electric panel), 2 position and off 65amp 240volt. The main panel is grounded to earth via large copper Rod. Generator to feed 2 hots and neutral to the panel via switch. Question #1. to keep both sources from having any issue with back feeding through the neutral Gen system and solar system could I switch neutrals in the Rotary switch for both systems and connect neutral to the grounding bar in the main panel? Since we use either the generator which is 12.5kw for big load usage including charging solar batteries through the main panel when required or we go through the solar system via the AC rotary switch and to the panel which is maxed at 5000kw. Never at the same time. Question #2 what would be the best solution for connecting these power sources? We are located on a remote Western Caribbean Island with no grid power so we are the power company.
The original installer has grounded the Solar Autotransformer, Inverter/ Charger and PV breaker panel together at a bar and then to a seperate ground rod which is approx 11' from the main Panel Grounding rod. Suggestions and Advice is greatly appreciated.

I think I'll need to see a sketch of this system. I can't really follow your description. Depending on how you use the autotransformer, and how you do your grounding and neutral to ground bonding, you can end up with circulating currents in the system. The Victron autotransformers are particularly prone to this because they are asymmetric, i.e. the two halves of the windings are NOT equal, so one side may be 107V and the other side 115V.

 

[sodamo]

Hard for me to follow as well. My old FX system used an autotransformer to make 240 from the 120 inverters. Would hope Victron has documentation. As I recall all the neutrals and grounds were common.

 

[sodamo]

Last of the parts arrived. Now I need to play with the wiring to get switch and relay correct.

 

[sodamo]

My apologies for not keeping up. Have had a few challenges and this project took a back seat.
Today the system is basically functional

 

[sodamo]

This first Pic is the Radiant inverter controlling the Kohler propane generator