Off grid Generator Imbalance

[Dave M7040]

Maybe I am missing something but I will throw this out.
Portable gensets are made with the neutral bonded to the generator frame and they have a label saying this.
Backup gensets have floating neutrals. My portable honda 3,500 watt requires a different transfer switch than my 20 kw Generac unit.
With the Honda the neutral is switched and with the generac it is not.
I know you are off grid and perhaps this observation is not relevant but I think the floating neutral design of your large unit does not have a ground reference for the neutral.
Others with more knowledge will add to this.
Dave M7040

 

[sodamo]

Huge difference between "Below were either 0 or open" . What is the Delta?

I will have to re measure these as my friend did the measurements, I took notes.

If there is transfer switch. NO TRANSFER SWITCH. Does make me wonder if that is part of the problem if there is something about a transfer switch the generator is expecting but not there.

Are you running AC generator power direct into the Outback and using it to switch from Inverted DC power to generator power? Direct to the AC In buses on the Outback panel. I don't normally run on ByPass. The Generator powers the Chargers in the inverters and my understanding is it also passes through meaning I not generating any inverted power.


Are the generators bonded or open? Is the outback bonded or open? What kind of a ground system? Bond screws in or out in the breaker panels?

Sorry, but these I can't answer. I have asked the generator people but not received and answer. The Outback and ground system were installed and inspected according to code. Have also worked without problem with my old generator and my smaller gas generator.

All 6/4 cable or is there over head neutral supported service wire ?
The only connection is the 6-4 cable

David Sent from my iPad Air using TractorByNet

 

[sodamo]

Maybe I am missing something but I will throw this out. Portable gensets are made with the neutral bonded to the generator frame and they have a label saying this. Backup gensets have floating neutrals. My portable honda 3,500 watt requires a different transfer switch than my 20 kw Generac unit. With the Honda the neutral is switched and with the generac it is not. I know you are off grid and perhaps this observation is not relevant but I think the floating neutral design of your large unit does not have a ground reference for the neutral. Others with more knowledge will add to this. Dave M7040

The generator guy was going to compare his wiring to the portable (which works without imbalance) but has not informed me of his findings.

Neither has a transfer switch, but a direct plug in connection.

David Sent from my iPad Air using TractorByNet

 

[buickanddeere]

An ohm meter and 15 seconds will verify if the generator's neutral is open or bonded.
I made a typo in an earlier response but corrected it to what I intended about the transfer switch.
I'm 99% certain there is neutral current flowing from a ground rod to another ground rod/chassis. The voltage difference is due the ground system having a high resistance.
Again , contrary to what some other folk here think. The ground system is not supposed to carry working current that is operating a load.

 

[sodamo]

Sorry for the delay, but I wanted to redo the measurements and did so a number of times and over two days, slight variance but probably due more to my slowness at times. The generator case wasn't designed with me poking around inside.

Generator measurements

Resistance
Gen stopped, Outback or any other loads disconnected, Breakers off
Measured with Fluke 117
Measured at top of alternator, where windings connect to output
L1 / L2 - 1.0
L1 /N, - .7 (u5 winding)
L2/N, - .5 (w5 winding)
L1/Earth - OL
L2/Earth - OL
L1/Gen case - OL
L2/Gen case - OL
N/Earth - OL
N/Gen case - 1.0

Note: no physical ground between system and generator
Earth is cable to bolt on engine block
Case is cable connected to bolt on rear of alternator
READINGS HAD TENDENCY TO FLUCTUATE BUT SEEMED TO SETTLE ABOUT 15 SECONDS

Voltage
Gen running, Outback or any other loads DISCONNECTED, Breakers OFF
On DSE7220 screen:
L1/L2 v- 232
L1-N - 115
L2 - N - 115

At alternator
L1 / L2 - 232
L1 /N - 116
L2/N - 116
L1/Earth - 109
L2/Earth - 116
N/Earth - 15.8

Voltage (AC on Fluke)
Gen running, Outback CONNECTED, Breaker ON
On DSE7220 screen:
L1-N - 110
L2 - N - 120

At alternator & MAIN BREAKER
L1 / L2 - 232
L1 /N - 111
L2/N - 121
L1/Earth - 110
L2/Earth - 120
N/Earth - 13.8

Maybe this is insightful?
David

 

[Industrial Toys]

I've mentioned this many times before. A friend suggested using a transformer on my gernerators and I have never looked back. All generators and inverters only supply 220 with no neutral connection at all, and the transformer makes the neutral for your house/loads. You only use one side of the transformer 110/220, I guess like an auto transformer and the other side does not matter what voltage it is, as you don't use it. The generators always run perfectly balanced and you never ever have to think about balancing loads from one side to the other.

 

[SPYDERLK]

Sorry for the delay, but I wanted to redo the measurements and did so a number of times and over two days, slight variance but probably due more to my slowness at times. The generator case wasn't designed with me poking around inside.

Generator measurements

Resistance
Gen stopped, Outback or any other loads disconnected, Breakers off
Measured with Fluke 117
Measured at top of alternator, where windings connect to output
L1 / L2 - 1.0
L1 /N, - .7 (u5 winding)
L2/N, - .5 (w5 winding)
L1/Earth - OL
L2/Earth - OL
L1/Gen case - OL
L2/Gen case - OL
N/Earth - OL
N/Gen case - 1.0

Note: no physical ground between system and generator
Earth is cable to bolt on engine block
Case is cable connected to bolt on rear of alternator
READINGS HAD TENDENCY TO FLUCTUATE BUT SEEMED TO SETTLE ABOUT 15 SECONDS

Voltage
Gen running, Outback or any other loads DISCONNECTED, Breakers OFF
On DSE7220 screen:
L1/L2 v- 232
L1-N - 115
L2 - N - 115

At alternator
L1 / L2 - 232
L1 /N - 116
L2/N - 116
L1/Earth - 109
L2/Earth - 116
N/Earth - 15.8

Voltage (AC on Fluke)
Gen running, Outback CONNECTED, Breaker ON
On DSE7220 screen:
L1-N - 110
L2 - N - 120

At alternator & MAIN BREAKER
L1 / L2 - 232
L1 /N - 111
L2/N - 121
L1/Earth - 110
L2/Earth - 120
N/Earth - 13.8

Maybe this is insightful?
David

I think those should be identical. Theres something wrong with the windings.
larry

 

[Industrial Toys]

I find it a little strange that your resistance readings for the windings vary but the voltage is identical.I have not worked on many gensets, but I know they can be challenging. I had one recently where I got all the right readings and yet could not get that brushless genset to self excite. Just changed the whole gen end! Fortunately is was a Northern cheapie.

 

[buickanddeere]

Sorry for the delay, but I wanted to redo the measurements and did so a number of times and over two days, slight variance but probably due more to my slowness at times. The generator case wasn't designed with me poking around inside.

Generator measurements

Resistance
Gen stopped, Outback or any other loads disconnected, Breakers off
Measured with Fluke 117
Measured at top of alternator, where windings connect to output
L1 / L2 - 1.0
L1 /N, - .7 (u5 winding)
L2/N, - .5 (w5 winding)
L1/Earth - OL
L2/Earth - OL
L1/Gen case - OL
L2/Gen case - OL
N/Earth - OL
N/Gen case - 1.0

Note: no physical ground between system and generator
Earth is cable to bolt on engine block
Case is cable connected to bolt on rear of alternator
READINGS HAD TENDENCY TO FLUCTUATE BUT SEEMED TO SETTLE ABOUT 15 SECONDS

Voltage
Gen running, Outback or any other loads DISCONNECTED, Breakers OFF
On DSE7220 screen:
L1/L2 v- 232
L1-N - 115
L2 - N - 115

At alternator
L1 / L2 - 232
L1 /N - 116
L2/N - 116
L1/Earth - 109
L2/Earth - 116
N/Earth - 15.8

Voltage (AC on Fluke)
Gen running, Outback CONNECTED, Breaker ON
On DSE7220 screen:
L1-N - 110
L2 - N - 120

At alternator & MAIN BREAKER
L1 / L2 - 232
L1 /N - 111
L2/N - 121
L1/Earth - 110
L2/Earth - 120
N/Earth - 13.8

Maybe this is insightful?
David

There is a conflict there. If there is low resistance from the neutral bar to the chassis, the generator is bonded. Yet other readings indicate an open circuit between L1 or L2 and earth.
Neutral is connected to L1 and L2 via the windings.

 

[buickanddeere]

I've mentioned this many times before. A friend suggested using a transformer on my gernerators and I have never looked back. All generators and inverters only supply 220 with no neutral connection at all, and the transformer makes the neutral for your house/loads. You only use one side of the transformer 110/220, I guess like an auto transformer and the other side does not matter what voltage it is, as you don't use it. The generators always run perfectly balanced and you never ever have to think about balancing loads from one side to the other.

I have the similar setup. Full balanced loads using both generaror windings at all times. One does have to check every ground and neutral path to ensure neutral current never flows in the ground system.