Generator Quitting on Low Voltage

[mkgrady]

I have a customer with a Briggs & Stratton 10KW generator. It came with a Cutler Hammer auto transfer panel. I installed it four years ago and I have been maintaing it ever since with no problems. Twice in the last couple of months it has shut down due to "Low Voltage". This is according to the remote signal indicator inside the house. It has a blinking LED that flashes codes to indicate a fault condition.

The manual lists the following problems that could cause a Low Voltage: restricted fuel flow, broken or disconnected signal lead, a failed alternator winding, control panel CB is open, generator is overloaded. Since the house is empty it can't be overloaded.

The first time it shut down they had just had a gas leak and a repair that was unrelated to the generator. I attributed the shutdown to a lack of fuel, figuring it might have been sucking air. That was a few weeks ago. I stopped by (the house is vacant for the winter) last week during a storm with a power outage. I expected to see the generator running but instead it was shutdown on Low Voltage.

It starts right up and runs for a couple of minutes and then shuts down. I think I'll go back tomorrow to see if it shuts down with no load like when it is being exercised. Anybody have any Ideas?

Thanks in advance, Mike

 

[ceb58]

The first time it shut down they had just had a gas leak and a repair that was unrelated to the generator. I attributed the shutdown to a lack of fuel, figuring it might have been sucking air. That was a few weeks ago. I stopped by (the house is vacant for the winter) last week during a storm with a power outage. I expected to see the generator running but instead it was shutdown on Low Voltage.

It starts right up and runs for a couple of minutes and then shuts down

LP or nat. gas?
If the gen. has been running for 4 years with no problem the gas supply would be the first clue I would look into. Even though the gas line repair was not related to the gen. set the line could have air in it and need purging or whom ever made the repair did some adjusting of regulators. The first thing I think I would do is bleed the line and hook up a manometer to check the water column with the gen. running.

 

[mkgrady]

LP or nat. gas?
If the gen. has been running for 4 years with no problem the gas supply would be the first clue I would look into. Even though the gas line repair was not related to the gen. set the line could have air in it and need purging or whom ever made the repair did some adjusting of regulators. The first thing I think I would do is bleed the line and hook up a manometer to check the water column with the gen. running.

It is nat gas. Thanks for that advice. I would not have thought to have the engine running for the measurement but that sure makes sense. I will have the plumber/gas fitter take those measurements. I imagine the installation manual will tell me the gas measurement it needs. In the mean time I'm open to other suggestions.

 

[hillbilly1]

I think it's a Generac clone, if so, it requires 10"-12" W.C. on the gas pressure. I would also check for any compressor loads that may have been added without your knowledge. High head pressure on a compressor will also cause a low voltage condition due to overload. Refrigerators can also cause this if the compressor was stopped, then restarted in a short period of time (also high head pressure issue).

 

[mkgrady]

I think it's a Generac clone, if so, it requires 10"-12" W.C. on the gas pressure. I would also check for any compressor loads that may have been added without your knowledge. High head pressure on a compressor will also cause a low voltage condition due to overload. Refrigerators can also cause this if the compressor was stopped, then restarted in a short period of time (also high head pressure issue).

To rule out the fridge I guess I would unplug it and see if the condition changes. I can't imagine any other compressor loads in this house that are connected to the generator.

It may be a Generac clone, I don't know. It has a 570 cc Vanguard V-Twin OHV engine.

 

[ceb58]

I think it's a Generac clone, if so, it requires 10"-12" W.C. on the gas pressure. I would also check for any compressor loads that may have been added without your knowledge. High head pressure on a compressor will also cause a low voltage condition due to overload. Refrigerators can also cause this if the compressor was stopped, then restarted in a short period of time (also high head pressure issue).

More than likely it is a clone. I will say this as you may or may not know but the 10kw unit on nat. gas is only good for around 8kw. Try turning off all circ. that are fed by the gen and check voltage with no load then start turning them on one by one and see what happens to the voltage. I am still going with my first thought air in the line or some one readjusted regulator. Thought just pop into my mind:-? When they fixed the leak on the gas line did they turn the main valve on the meter all the way on? It may be that if there is air in the line but there is enough gas mixed with it to crank but not enough to supply engine under load. Crank gen. with no load and let it run 10-15 min and then start putting loads on it that should be enough time if there is air in system to get it out. If that doesn't work then go for checking water column.

 

[hillbilly1]

To rule out the fridge I guess I would unplug it and see if the condition changes. I can't imagine any other compressor loads in this house that are connected to the generator.

It may be a Generac clone, I don't know. It has a 570 cc Vanguard V-Twin OHV engine.

I just noticed your in Mass, You probably do not have heatpumps up there, unless they are geothermal. I have too many Generac reps claim their units will run a A/C unit, but usually will not if the FLA is over 20 amps.

 

[mkgrady]

More than likely it is a clone. I will say this as you may or may not know but the 10kw unit on nat. gas is only good for around 8kw. Try turning off all circ. that are fed by the gen and check voltage with no load then start turning them on one by one and see what happens to the voltage. I am still going with my first thought air in the line or some one readjusted regulator. Thought just pop into my mind:-? When they fixed the leak on the gas line did they turn the main valve on the meter all the way on? It may be that if there is air in the line but there is enough gas mixed with it to crank but not enough to supply engine under load. Crank gen. with no load and let it run 10-15 min and then start putting loads on it that should be enough time if there is air in system to get it out. If that doesn't work then go for checking water column.

Good ideas. Gives me lots to check when I go back tomorrow. I do believe though that 8KW is plenty to power this vacant house.

I just noticed your in Mass, You probably do not have heatpumps up there, unless they are geothermal. I have too many Generac reps claim their units will run a A/C unit, but usually will not if the FLA is over 20 amps.

No heat pump here. The heat is gas fired furnace. Now that I think about it, maybe the furnace running while the gen is running is starving the gen of fuel. Of course it needs to be able to run both but it gives me another thing to experiment with.

 

[mkgrady]

I think I have ruled out gas flow as the suspect. I went to the home and ran the generator in Manual. In Manual it has no load on it at all, just like it would be during a weekly exercise. It ran for a half hour with no problems. The voltage was steady and around 245 the whole time.

Still thinking gas flow could be the problem I set the controller to Automatic, shut off all the circuits that are fed from the transfer panel and simulated a power outage by shutting off the normal feed 50 amp CB. This caused the gen to run with no load on it just like in the manual mode as before.

My plan was to add load by switching on one of the eight or ten circuits at a time while checking voltage at all times. Well, voltage was normal but before I could add any load the gen cut out on low voltage again.

It finally occurred to me that although the normal power contactor opened the generator contactor never did close, nor did it receive a voltage signal to close. The coils of each contactor get their signals from the normal power source or the gen source, and they each get their common from the z printed circuit control board. This common also goes thru a NC contact of the oposite contactor. Presumably this keeps both contactors from closing at the same time.

I suspect the circuit board is bad and I hope I can buy a replacement. The only other thing I can check is the NC contact on the normal contactor. So, has anybody had a similar experience that you got resolved? Any other comments?

 

[ceb58]

I think I have ruled out gas flow as the suspect. I went to the home and ran the generator in Manual. In Manual it has no load on it at all, just like it would be during a weekly exercise. It ran for a half hour with no problems. The voltage was steady and around 245 the whole time.

Still thinking gas flow could be the problem I set the controller to Automatic, shut off all the circuits that are fed from the transfer panel and simulated a power outage by shutting off the normal feed 50 amp CB. This caused the gen to run with no load on it just like in the manual mode as before.

My plan was to add load by switching on one of the eight or ten circuits at a time while checking voltage at all times. Well, voltage was normal but before I could add any load the gen cut out on low voltage again.

It finally occurred to me that although the normal power contactor opened the generator contactor never did close, nor did it receive a voltage signal to close. The coils of each contactor get their signals from the normal power source or the gen source, and they each get their common from the z printed circuit control board. This common also goes thru a NC contact of the oposite contactor. Presumably this keeps both contactors from closing at the same time.

I suspect the circuit board is bad and I hope I can buy a replacement. The only other thing I can check is the NC contact on the normal contactor. So, has anybody had a similar experience that you got resolved? Any other comments?

You may need to check voltage coming to the gen. contactor to see if it is receiving voltage to close the contact. Could be a bad coil in the contactor. It can be a real hair puller. Good luck

 

[mkgrady]

You may need to check voltage coming to the gen. contactor to see if it is receiving voltage to close the contact. Could be a bad coil in the contactor. It can be a real hair puller. Good luck

I verified that the gen is putting out 245 volts to the transfer contactor and the circuit board LED indicates it is seeing voltage from the generator. For some reason the signal to the contactor coil is not getting there. If the coil was receiving voltage and wasn't pulling in I would suspect the coil but that is not the case.

Like most circuit boards they don't give you enough info to troubleshoot them so I'm thinking of replaceing it. Problem is, it's just a guess and it will be embarrassing if I guess wrong.

I'd feel better if some people chimed in and said they had a similar experience and replacing the board fixed it.

 

[busman]

I've had this problem with B&S generators before. Check the multi-wire connector at the control board in the housing. B&S uses a step-down transformer for the utility monitoring (240V/24V), but not for the generator monitoring. This means that they send 240V to the control board (not a good design). These connections/boards have a history of going POOF.

Mark

 

[yucan2]

I verified that the gen is putting out 245 volts to the transfer contactor and the circuit board LED indicates it is seeing voltage from the generator. For some reason the signal to the contactor coil is not getting there. If the coil was receiving voltage and wasn't pulling in I would suspect the coil but that is not the case.

Like most circuit boards they don't give you enough info to troubleshoot them so I'm thinking of replaceing it. Problem is, it's just a guess and it will be embarrassing if I guess wrong.

I'd feel better if some people chimed in and said they had a similar experience and replacing the board fixed it.

I have not seen this however there are 8 fault codes. What you describe would be 3 flashes. Are there others? Do you have manual to simulate the other 6? Not 7 because no need to simulate battery failure.

I like others am leaning more towards a loose connection rather than a bad board. I'm not certain if the fault stays resident in memory? How are you clearing the fault notice? By turning off the generator output breaker for 30 seconds?

If connections are solid and the tests above can be simulated, finally verify that the voltage really does not drop significantly at the output of the generator in auto. Would not be apparent in manual as it would not matter.
Look closely for a loose connection.

 

[mkgrady]

I've had this problem with B&S generators before. Check the multi-wire connector at the control board in the housing. B&S uses a step-down transformer for the utility monitoring (240V/24V), but not for the generator monitoring. This means that they send 240V to the control board (not a good design). These connections/boards have a history of going POOF.

Mark

I think you are saying there is a connector and control board at the generator. I have been looking at the control board inside the transfer panel. I will look for one in the gen enclosure and try to find corrosion. If I find a suspect connector should I try some WD-40 on it? If it is a bad board (at either end) will there be an indication it is bad?

The board inside the transfer panel lights a green LED when it receives normal power. When I kill the normal feed the green light goes out and the normal contactor drops out. After the gen starts I get a green LED. When the green LED comes on I would expect the gen contactor coil to receive voltage and pull in but it doesn't.

Thanks for the help

 

[busman]

It's the board inside the generator. It's not really corrosion that's the problem. It's just that it's really a low voltage style multi-pin connector being used for 240V. Look for smoke/arc damage on the connector/board.

Mark

PS: In fact, I had this same problem with my personal generator during the big snowstorm here last month.

 

[mkgrady]

I have not seen this however there are 8 fault codes. What you describe would be 3 flashes. Are there others? Do you have manual to simulate the other 6? Not 7 because no need to simulate battery failure.

I like others am leaning more towards a loose connection rather than a bad board. I'm not certain if the fault stays resident in memory? How are you clearing the fault notice? By turning off the generator output breaker for 30 seconds?

If connections are solid and the tests above can be simulated, finally verify that the voltage really does not drop significantly at the output of the generator in auto. Would not be apparent in manual as it would not matter.
Look closely for a loose connection.

Yes, I'm getting three flashes and no others. I have the owners and installation, and transfer panel manuals but I did not see any info on simulating fault codes. The manuals just describes what all the different codes mean. Am I missing a manual?

To clear the fault code (and make the LED stop blinking) I am using the Man/Off/Auto control switch at the gen. I turn it to off for a few seconds. The light stops blinking and then I put it back in Auto. I then get a steady light to indicate normal operation.

I carefully monitored the gen voltage output for the short time it runs on Auto before shutting down. It was reading about 245V.

Thanks for info.

 

[mkgrady]

It's the board inside the generator. It's not really corrosion that's the problem. It's just that it's really a low voltage style multi-pin connector being used for 240V. Look for smoke/arc damage on the connector/board.

Mark

PS: In fact, I had this same problem with my personal generator during the big snowstorm here last month.

Thanks for that. I hope my problem is that simple. Any suggestion on a good fix for that? Sounds like replacing the same connector would not be adviseable. Did you go with wire nuts or a terminal strip or something else?

 

[busman]

I've ordered the replacement connector from Briggs (thru the local dealer) for about $30 and will use butt splices when it arrives. Because the problem was right at the board, the generator output was fine, but the board thought it was low voltage.

Mark

PS: I'll try to remember to post a picture later today.

 

[mkgrady]

I've ordered the replacement connector from Briggs (thru the local dealer) for about $30 and will use butt splices when it arrives. Because the problem was right at the board, the generator output was fine, but the board thought it was low voltage.

Mark

PS: I'll try to remember to post a picture later today.

Mark, I looked for a connector at the generator as you described but I could not find one. I do however think you must be right because I think I have ruled out a transfer switch problem. I have replaced its control board and rung out all the wires and contacts.

 

[JWCELECTRIC]

MK,

Is there a inline gas filter before or after regulator that prevents dust from getting in the generator? It may be clogged and need to be changed or cleaned

- JWC