Off grid Generator Imbalance

[sodamo]

While not a tractor topic, I consider TBN to be a superb brain trust.

Last year in a feeble attempt to improve my offgrid setup (10kw PV, 3 MX60s, 4 FX3048, x240, Mate3), I decided to upgrade my generator.

Old Genset : 24kw, New Holland Shanghai diesel engine, Monicom control panel, 25 gal tank. Provided good service almost 7 years and still running when I sold it.

New Genset: 24kw, Yangdong Diesel engine, Deep Sea 7220 control panel, 100 gallon tank.

Smaller backup Genset: Home Depot off the shelf, gas powered Ridgid 8000.

When hooked up, my new Genset always has an imbalance between L1 / L2.
My observations:
There is 0 imbalance with Genset running but not hooked up.
Imbalance registers immediately once connected at the DS7220 readout and fluke meter readings anywhere from cable connection to Outback buses.
Imbalance is usually 5 volts at beginning, but increases over time, highest observed was over 30.
Cable to Outback will heat up and has damaged connection.
Breaker to X240 will trip, but not always. I added fan to x240 but no help.
Microwave and washing machine control boards don't like and error out.

Hook up Variations:
My cable into Outback is same that has been in service over 7 years. 10-4 with connector on one end thru house type watt meter to outback ACIn buses and neutral. Initially the connector was 30 twist lock type for connection into old Genset or Ridgid but I replaced with 50amp plug. I have a short connector conversion to hook into the Ridgid.
Have tested with ground connected and not connected at Outback without effect.
Same cable hooked into Ridgid generator, same Mate settings shows no imbalance, either initially or after time.

Various Generator connections tested.
Cable to generator main breaker (200amp)
Cable to generator 50 amp socket with ground Cable to generator 50 amp socket without ground
Note - generator is not grounded separately, neither is Ridgid nor old Genset.

Other tests: I have disconnected all loads from the AC side of Outback by turning off breakers in main distribution panel to house.
I have have turned off inverter output breakers individually until all were off
I have shut down individual inverters until just 1-2phase Master (port 1)is on.
I have tried various mate settings for generator from min to max and some at zero.
I have spent time with on phone with Outback Tech support and couldn't resolve anything.
Generator guy checked and couldn't find anything wrong with Genset. At this point he suspects a grounding issue.

I have replaced 1 fx3048. Mate3 was also replaced by Outback.
There are no error messages.

So, to say I am at a loss would be an understatement. What else can I check, test, look to verify is correct? Not only is this a PITA, but a safety hazard due to the heat issue.
Any and all suggestions welcome.

<CSIHelper: 0x17e8e840>

 

[KubotainNH]

Sounds like a grounding issue to me, maybe inside the genset itself? Can you rent another genset to see if it goes away? Or maybe add a balancing transformer like the electric company uses when there a bad ground making this same imbalance.

 

[sodamo]

Using the Ridgid 8000 generator was my solution versus renting another. No visible problem when running the Ridgid either initially or over time. To me, that is suggestive that the problem is within the new Genset. Any ideas on checking that grounding?

I have also considered adding a transformer, not ruled it out, but prefer to eliminate any other problem first. I have another x240 transformer from Outback that supposedly can be used in that fashion.

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[techman]

Sounds like crap chinese generator

 

[grsthegreat]

I question the use of the 10/4 cable. What does this supply.
10/4 copper is rated at 40 amps, but by convention should not pull more than 30 amps. Just adding a larger outlet (50 amps) changes nothing. A 24 kw gen provides 100 amps.

Am i not understanding something here

 

[Mace Canute]

Using the Ridgid 8000 generator was my solution versus renting another. No visible problem when running the Ridgid either initially or over time. To me, that is suggestive that the problem is within the new Genset. Any ideas on checking that grounding?

I have also considered adding a transformer, not ruled it out, but prefer to eliminate any other problem first. I have another x240 transformer from Outback that supposedly can be used in that fashion.

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Classic symptom of a bad neutral is severe voltage difference between each hot leg and neutral under load. Since it only happens with Deep Sea 7220 Genset I have to agree that the problem is located within the GS7220.

 

[CobyRupert]

Voltage imbalance usually means a bad neutral. "Bad neutral" can mean a lot of things. Could be bad "neutral" cable and/or connections, or bad bonding between neutral and ground (electrode) connections, bad ground connections.
I also assume you have some sort of transfer switch? Was this modified? Does it have a switched neutral?

Megger each winding.

Hard to follow your description. What is the Outback? What is the x240?

 

[buickanddeere]

As previously pointed out this appears to be a ground and neutral system problem.
Despite how many times laymen electricians are told by engineers, utity professionals, electrical inspectors and licensed trades persons. There are laymen electricians who still augue that ground and neutral are the same.
Is there any connection in any way back to the utility with your home system?
Are the generators bonded or not
Neutrals are insulated load carrying conductors that are held to near earth potential by a bond to earth at the utility service/supply point.
The ground system is usually bare and is used to hold metallic compoents to near earth potential.

 

[sodamo]

Thanks for the input.
Some clarification:
"generator main breaker (200amp)" should read 125 amp
"My cable into Outback is same that has been in service over 7 years. 10-4 with connector on one..." should read 6-4...

This is a totally off grid system, no grid power at all.

Outback is the name of the off grid system manufacturer: Outback Power Inc. - Home
X240 is an Outback transformer. Used in various ways, step up,step down, balancing, etc.

There is no transfer switch.
Neutral is not switched.

Had a retired electrician friend over today for a look.

Measured the resistance at genset:
L1 / L2 , -.5
L1 /N, - .5
L2/N, - .5

Below were either 0 or open
L1/Earth
L2/Earth
L1/Gen case
L2/Gen case
N/Earth
N/Gen case
Earth/case

Changed out the avr, slight change in voltage from 121 to 115, but no impact on end result, still L1/L2 delta under load.

Tried an isolated 240 load, welder directly connected, still a delta when turned on.

Verified that no imbalance when connected to the Ridgid genset.

Need to find wiring instructions t0 incorporate the x240 transformer.

the search continues - frustrating.

 

[buickanddeere]

Huge difference between "Below were either 0 or open" .
What is the Delta?
If there is no transfer switch. Are you running AC generator power direct into the Outback and using it to switch from Inverted DC power to generator 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?
All 6/4 cable or is there over head neutral supported service wire ?

 

[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.