Temporary generator install - overloading generator

Discussion about OutBack Inverters in Off Grid Applications

Moderators: OutBack, OutBack Moderator Team

Post Reply
Matty
Forum Whiz
Posts: 46
Joined: Sun Sep 04, 2005 3:17 pm
My RE system: .
Off Grid Setup (primary residence)
2 Outback Power VFX3648
MX60 MPPT Charge Controller
MATE2 Controller
12 Kyocera 190GT @ 2.28kW
16 6v US Battery S6 L16 HC @ 48v
Generac 7k Propane Backup Generator
Location: Northern Idaho, USA

Temporary generator install - overloading generator

Post by Matty » Thu Mar 26, 2020 8:21 am

Good morning!

I have 2 VFX3648 inverters controlled by a Mate (I believe first gen). My whole house generator blew a board about a week ago and I've been running on a Honda 3000is generator for the time being. We run our generator about 1-2 times per week with the weather we're having lately. My main issue is that I can only run one inverter (master) with the generator. Today I had a bit of an aha moment and here is what I did.

I have a breaker setup that will allow me to have the generator on either inverter. I removed any breakers that were using both legs in my AC breaker box so I wouldn't have any 220 loads which would cause issues with this generator setup.

I turned the acs/gen aac limit on both ports down to 2aac which barely causes any load on the generator on one leg... as expected.

When allowing the power to flow to the second generator, everything is fine and the transfer throws without issue.

The main problem is that the generator slowly increased to a significant load and trips it's overload fail safe. This should be drawing no more than 500 watts at this level. When I run the generator on one leg, I am using 12aac / ~1200-1500w.

I have no other loads running while I do this.

Any thoughts as to what I am doing wrong? Please let me know if I can provide any further details.

Thank you!
Matt

sparksalot
Forum Guru
Posts: 285
Joined: Sun Jul 17, 2016 5:31 am
My RE system: FLEXpower TWO VFXR3648A Grid-Tied and Battery Backup Hybrid, Mate3s
Using Two Midnite 200 Classic Charge Controllers

Traction battery FLA 48 volt 805Ahr.

32 SolarWorld 245w mono, 2x-4S-4P
6 REC 320w on micro-inverters

Re: Temporary generator install - overloading generator

Post by sparksalot » Thu Mar 26, 2020 9:09 am

So, the Honda 3000i is unable to output any 220 vac???

Is the non-operating whole-house generator isolated/disconnected from the normal AC electrical system?

Matty
Forum Whiz
Posts: 46
Joined: Sun Sep 04, 2005 3:17 pm
My RE system: .
Off Grid Setup (primary residence)
2 Outback Power VFX3648
MX60 MPPT Charge Controller
MATE2 Controller
12 Kyocera 190GT @ 2.28kW
16 6v US Battery S6 L16 HC @ 48v
Generac 7k Propane Backup Generator
Location: Northern Idaho, USA

Re: Temporary generator install - overloading generator

Post by Matty » Thu Mar 26, 2020 9:42 am

I'm in the US, I should have stated that. The Honda doesn't have a 220v output only 110v.. The generator only goes to the inverters which go to the house AC through their internal transfer switches.

raysun
Forum Emperor
Posts: 1669
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Temporary generator install - overloading generator

Post by raysun » Thu Mar 26, 2020 9:59 am

It sounds like the AC IN wiring scheme isn't doing what it was intended to do. Double check that the generator is truly powering only one leg of the house circuits and is feeding only one inverter. (Dialing down AC IN on the second inverter isn't likely enough to keep AC IN from reaching its transfer switch.)

Both inverters have automatic battery charging functions when AC IN is applied. What is the state of the charger settings on both inverters?

Matty
Forum Whiz
Posts: 46
Joined: Sun Sep 04, 2005 3:17 pm
My RE system: .
Off Grid Setup (primary residence)
2 Outback Power VFX3648
MX60 MPPT Charge Controller
MATE2 Controller
12 Kyocera 190GT @ 2.28kW
16 6v US Battery S6 L16 HC @ 48v
Generac 7k Propane Backup Generator
Location: Northern Idaho, USA

Re: Temporary generator install - overloading generator

Post by Matty » Thu Mar 26, 2020 10:05 am

Thank you for the replies first off!! I really appreciate it.

I have no problem powering one leg, it's when I switch to using both inverters powering both legs that it becomes the issue. I don't have any breakers sitting on both legs using 220v. My thought was that if I have the generator powering both inverters I could keep both legs hot for 110v power. I may be misunderstanding how this all works.

The problem is that when the slave inverter kicks into charging mode, it continues to ramp up to a pretty significant load which then trips the overload on the Honda. I have dialed down the AC in and Charger max amps to their lowest specifically to keep the inverters from pulling too much power when charging.

raysun
Forum Emperor
Posts: 1669
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Temporary generator install - overloading generator

Post by raysun » Thu Mar 26, 2020 12:06 pm

I don't think the 3000i can do what you are looking to do. When AC IN is used, the inverters are bypassed, the generator power is fed directly to the house circuits.

A 220V house wiring scheme is split phase with both L1 and L2 110V hot legs connected to a common neutral. Feeding both legs from the same phase could potentially overload neutral (or show some wiring defects like a loose neutral connection).

What happens when the inverters are disconnected from the AC panel? Do you still see the issue?

What happens when the battery chargers are set to MODE=OFF?

In any event, even if this scheme works, the 7kW AC OUT potential, coupled with battery charging load, is entirely too much for the 3000i, trooper that it is. It's a very good thing you have a small Honda though, there's lots of small generators that would be a smoking pile of slag by now pressed into this sort of duty.

Matty
Forum Whiz
Posts: 46
Joined: Sun Sep 04, 2005 3:17 pm
My RE system: .
Off Grid Setup (primary residence)
2 Outback Power VFX3648
MX60 MPPT Charge Controller
MATE2 Controller
12 Kyocera 190GT @ 2.28kW
16 6v US Battery S6 L16 HC @ 48v
Generac 7k Propane Backup Generator
Location: Northern Idaho, USA

Re: Temporary generator install - overloading generator

Post by Matty » Thu Mar 26, 2020 1:21 pm

So learning some more from this... looks like the common neutral is the issue. I'm not following the 180 rule in power I learned.

Thanks for the input again! Much appreciated as always.

raysun
Forum Emperor
Posts: 1669
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Temporary generator install - overloading generator

Post by raysun » Thu Mar 26, 2020 3:07 pm

Matty wrote:
Thu Mar 26, 2020 1:21 pm
So learning some more from this... looks like the common neutral is the issue. I'm not following the 180 rule in power I learned.

Thanks for the input again! Much appreciated as always.
Put all critical loads on one side of the panel and balance the other side with the non-critical loads as much as possible. Put the generator on the inverter on the critical load side.

If the loads are modest enough, you'll have headroom for charging too.

Next, save alllll your pennies and buy a Honda EU7000is. Everyone who owns ones says it's the best thing they ever did, including me.

Upgrading from my wonderful EU3000is to the 7000 was a life changing experience.

Post Reply