yucan2
14kW, model #0055340.

Output bouncing around with no load but hovering around 60hz, 240 volts. With load, frequency drops to 40 and voltage around 180.

Adjusted governor. Frequency and voltage still erratic. Checked and adjusted valves. Same problem.

Suggestions?
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ceb58
yucan2;8549 wrote:
14kW, model #0055340.

Output bouncing around with no load but hovering around 60hz, 240 volts. With load, frequency drops to 40 and voltage around 180.

Adjusted governor. Frequency and voltage still erratic. Checked and adjusted valves. Same problem.

Suggestions?


You may want to start looking for a loose or partly broken neutral. Check, with a load, phase to ground. If you get a low voltage reading on one and a high reading on the other then there is a problem with the neutral conductor.
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mastr
How much load? How does the engine sound?
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yucan2
ceb58;8550 wrote:
You may want to start looking for a loose or partly broken neutral. Check, with a load, phase to ground. If you get a low voltage reading on one and a high reading on the other then there is a problem with the neutral conductor.


I'm reading low voltage phase to ground as well as phase to phase.
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yucan2
mastr;8551 wrote:
How much load? How does the engine sound?


Engine seems to be struggling slightly to maintain speed even with no load. Sounds slightly louder than normal but not excessively.
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ohmslaw
I would check several things.
gas pressure, choke open completely, spark, compression. spark plugs OK?
pull one cylinder wire at a time and see if the running speed changes.
I am leaning towards coils but so many possibilities here.
Choke one cylinder at a time with your finger while it is running. Does the speed change? Do they have equal suction?
OK I checked the model number is this a 14kw or an 8KW?
Tim
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ohmslaw
yucan2;8549 wrote:
14kW, model #0055340.

Output bouncing around with no load but hovering around 60hz, 240 volts. With load, frequency drops to 40 and voltage around 180.

Adjusted governor. Frequency and voltage still erratic. Checked and adjusted valves. Same problem.

Suggestions?

Adjusted governor tells me an 8 KW not a 14.
Tim
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yucan2
ohmslaw;8555 wrote:
Adjusted governor tells me an 8 KW not a 14.
Tim


Thanks Tim, and now I'm embarrassed. Time for some background.

A guy calls me and says he installed a 14kW for a customer a couple of years ago. He said it was a 14kW and gave me the model and serial number. Says recently it wouldn't carry the load.

I ran the numbers to determine warranty status. Unit was never registered. He asks that I go check it out and make repairs.

I head out expecting to find a stepper motor problem. Instead the unit has a mechanical governor and it never clicks that I'm not working on a 14kW. I even glanced at the nameplate. It's a centurion by the way, not that it matters.

I guess it was the power of suggestion, the mere mention of it being a 14kW got embedded in my brain and that was it. I spent the better part of Saturday working on that thing, scratching my head and saying this makes no sense. I kept thinking unit must be overloaded, but its a 14kW, it should be able to handle this load. :confused:

Connected load:
Alarm System
Ejector Pump
Sump Pump
(3) Freezers
(1) Refrigerator
Numerous Lights and televisions. This is a huge home.
In other words, the ATS breakers were all being used and supplying significant loads.

I could kick myself in the butt and ring the installers neck :eek: Instead I have to go back to the homeowners and explain to them why their "14kW" unit is bogging down.

I just can't believe I didn't catch this. Oh well. :mad:

BTW, I now think that this unit has been put through such a stressful load carrying workload for so long, (there have been numerous extended outages), that the now inability to carry a significant load is to be expected.

Can it be salvaged? Engine compression, voltage regulator, springs on the governor? All these areas have been severely taxed. So much for next Saturday.

Feel free to suggest any other potential problem areas to check. I'll research them all. It's personal now and its on my dime. Gotta try to make it right, within reason of course :D
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ohmslaw
So it is an 8 KW. Single cylinder mechanical governor. The governor needs to be set at 62.5 HZ no load. Can you manually bring up the rpm under load?
What is the compression? Has the air box been converted to LP/NG properly?
Air filter clean? Fuel Pressure?
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yucan2
ohmslaw;8557 wrote:
So it is an 8 KW. Single cylinder mechanical governor. The governor needs to be set at 62.5 HZ no load. Can you manually bring up the rpm under load?
What is the compression? Has the air box been converted to LP/NG properly?
Air filter clean? Fuel Pressure?


Yes, an 8kW. Couldn't get it to stabilize at 62.5. Jumping all over the place, between 58 and 63 or 64.

Air filter was clean. Running on NG. All seemed well in that regard. Didn't think pressure was an issue after (2) years but didn't check. Will check when I return, probably not before next Saturday. I'll look at compression also. Thanks again.
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mastr
If it was trying to start all 4 (or even 3) of those compressors at once, I guess it had good reason for struggling, on natural gas the set is rated 7kw. If you have time, put your ammeter on it and see what the actual load was.
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d11gnccer
Sorry to hijack your post but I'm really starting to wish Generac would start selling only through certified dealers. I need to rant.

I just recently spent several hours on a centurion 7/6kw during our last major outage. Dead battery, then found dead starter motor, then found broken carb linkage to governor. Get it running and the circuit board isn't sending power out on 194. By this time utility is back and board isn't sensing utility... because it isn't there. The governor was also set to 70 hertz.

Find a whole house switch, in a house with a 400 amp service. "Ma'am, I need to see your electrical panels. By the way, do you know who installed this?" The reply was "I don't know." Find a sub panel with an electric furnace, multiple freezers, and other various loads. Start pulling panel covers off and they are backfeeding through the sub panel to the other 200 amp panels!

Husband comes home and admits he had installed it.
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Skip Douglas SkipD
d11gnccer;8560 wrote:
Sorry to hijack your post but I'm really starting to wish Generac would start selling only through certified dealers. I need to rant.

I just recently spent several hours on a centurion 7/6kw during our last major outage. Dead battery, then found dead starter motor, then found broken carb linkage to governor. Get it running and the circuit board isn't sending power out on 194. By this time utility is back and board isn't sensing utility... because it isn't there. The governor was also set to 70 hertz.

Find a whole house switch, in a house with a 400 amp service. "Ma'am, I need to see your electrical panels. By the way, do you know who installed this?" The reply was "I don't know." Find a sub panel with an electric furnace, multiple freezers, and other various loads. Start pulling panel covers off and they are backfeeding through the sub panel to the other 200 amp panels!

Husband comes home and admits he had installed it.
That's a case where I would feel obligated to let the electrical inspector know what was discovered. Though I am not an attorney, I feel that I may be held partially liable if the house burned down and I had not reported the total disregard for following codes but others discovered that I had known of the situation.
Skip Douglas
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ceb58
yucan2;8556 wrote:
Thanks Tim, and now I'm embarrassed. Time for some background.

A guy calls me and says he installed a 14kW for a customer a couple of years ago. He said it was a 14kW and gave me the model and serial number. Says recently it wouldn't carry the load.

I ran the numbers to determine warranty status. Unit was never registered. He asks that I go check it out and make repairs.

I head out expecting to find a stepper motor problem. Instead the unit has a mechanical governor and it never clicks that I'm not working on a 14kW. I even glanced at the nameplate. It's a centurion by the way, not that it matters.

I guess it was the power of suggestion, the mere mention of it being a 14kW got embedded in my brain and that was it. I spent the better part of Saturday working on that thing, scratching my head and saying this makes no sense. I kept thinking unit must be overloaded, but its a 14kW, it should be able to handle this load. :confused:

Connected load:
Alarm System
Ejector Pump
Sump Pump
(3) Freezers
(1) Refrigerator
Numerous Lights and televisions. This is a huge home.
In other words, the ATS breakers were all being used and supplying significant loads.

I could kick myself in the butt and ring the installers neck :eek: Instead I have to go back to the homeowners and explain to them why their "14kW" unit is bogging down.

I just can't believe I didn't catch this. Oh well. :mad:

BTW, I now think that this unit has been put through such a stressful load carrying workload for so long, (there have been numerous extended outages), that the now inability to carry a significant load is to be expected.

Can it be salvaged? Engine compression, voltage regulator, springs on the governor? All these areas have been severely taxed. So much for next Saturday.

Feel free to suggest any other potential problem areas to check. I'll research them all. It's personal now and its on my dime. Gotta try to make it right, within reason of course :D


Leroy, when you go back clamp the feeder wires in the ATS and see what amp load you get. With the 3 freezers and 2 refg. I bet it pulls one hell of an amp draw. You say that it is an 8kw running on NG as you know this probably makes it a 6-7kw unit.
And I bet the installer did not install a disconnect with over-current protection between the gen. and the ATS. We have had lively discussions before on this subject but again I will bet that if you look at the disconnect on the gen. it is just that, a disconnect, that doesn't provide over-current protection. Sounds like the unit is about to give up the ghost.
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ohmslaw
ceb58;8563 wrote:
Leroy, when you go back clamp the feeder wires in the ATS and see what amp load you get. With the 3 freezers and 2 refg. I bet it pulls one hell of an amp draw. You say that it is an 8kw running on NG as you know this probably makes it a 6-7kw unit.
And I bet the installer did not install a disconnect with over-current protection between the gen. and the ATS. We have had lively discussions before on this subject but again I will bet that if you look at the disconnect on the gen. it is just that, a disconnect, that doesn't provide over-current protection. Sounds like the unit is about to give up the ghost.


Ceb,
Are you implying that the breakers in the Generac units are not over current protection devices and will not trip?
Tim
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yucan2
ceb58;8563 wrote:
Leroy, when you go back clamp the feeder wires in the ATS and see what amp load you get. With the 3 freezers and 2 refg. I bet it pulls one hell of an amp draw. You say that it is an 8kw running on NG as you know this probably makes it a 6-7kw unit.
And I bet the installer did not install a disconnect with over-current protection between the gen. and the ATS. We have had lively discussions before on this subject but again I will bet that if you look at the disconnect on the gen. it is just that, a disconnect, that doesn't provide over-current protection. Sounds like the unit is about to give up the ghost.


I feel you may be correct about it giving up the ghost though I will attempt to get it back into a normal operating range if at all possible.

As Tim pointed out, there is a 35 amp breaker in the generator that to my knowledge has never tripped, however, it would allow a maintained current draw of 35 amps on a leg over long periods, give or take, which I suspect has happened and the occasional in rush of startup current far exceeding the generators safe operating parameters thus causing the premature wear.

There is no additional over current protection.
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mastr
yucan2;8565 wrote:
...35 amp breaker in the generator that to my knowledge has never tripped...


And it probably won't ever trip. There is a good chance that the set won't make enough power to trip it. Circuit breakers alone are not adequate overload protection for most small generators, no matter who makes them. But they do satisfy the NEC and inspectors.

Natural gas fueled, on a "good" day that set will make 7kw, at 240 volts, so 29 amps. When that big load is dumped on and it falls down to 180 volts and only about 2400rpm, it can no longer produce full power. Giving the benefit of a doubt, lets say it can make 5.3kw (2/3 of the full 8kw propane rating, since the engine speed is down to 2/3), at 180 volts that is less than 30 amps. It will probably sit there and hammer until it melts before the 35A breaker would trip.
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Ira
Just curious...would the frequent overloading of the genset cause additional wear on the various electric motors, electronics, etc.?
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ceb58
ohmslaw;8564 wrote:
Ceb,
Are you implying that the breakers in the Generac units are not over current protection devices and will not trip?
Tim


Tim, what I am saying is I have seen some older units that have what looks like a breaker but it provides no over-current protection. It is just a disconnect. Square D makes a all in one disconnect for A/C units. It looks just like a breaker and has an amp rating stamped on it just like a regular breaker but if you open the cover it states on the side of the disco. "UNIT DOSE NOT PROVIDE OVERCURRENT PROTECTION" If the unit has this then it has not had any protection for the feeders or the gen.
By the residential calculation the demand factor for 1 refg and 3 freezers would be 3300va or 10amps. But this doesn't take into account the inrush of start up.
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ohmslaw
ceb58;8569 wrote:
Tim, what I am saying is I have seen some older units that have what looks like a breaker but it provides no over-current protection. It is just a disconnect. Square D makes a all in one disconnect for A/C units. It looks just like a breaker and has an amp rating stamped on it just like a regular breaker but if you open the cover it states on the side of the disco. "UNIT DOSE NOT PROVIDE OVERCURRENT PROTECTION" If the unit has this then it has not had any protection for the feeders or the gen.
By the residential calculation the demand factor for 1 refg and 3 freezers would be 3300va or 10amps. But this doesn't take into account the inrush of start up.


OK that makes sense. I have never seen a Generac without over current protection. I do not think this is a load issue but we will not know until Leroy gets an amp probe on it. I am still leaning towards a coil issue. The unit appears to be running erratic not trying to stall or slow dramatically due to load. I also would follow the book for setting the Governor.
My process is to reset the shaft, Loosen both springs a couple of turns and then adjust the main to 61.5 no load . after that get to 62.5/63 with the secondary.
TIM
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yucan2
ohmslaw;8570 wrote:
OK that makes sense. I have never seen a Generac without over current protection. I do not think this is a load issue but we will not know until Leroy gets an amp probe on it. I am still leaning towards a coil issue. The unit appears to be running erratic not trying to stall or slow dramatically due to load. I also would follow the book for setting the Governor.
My process is to reset the shaft, Loosen both springs a couple of turns and then adjust the main to 61.5 no load . after that get to 62.5/63 with the secondary.
TIM


I don't think it's a load issue now at this point either, though I believe too much load caused the problem.

Using the procedure you and the manual described, I turned the choke shaft fully clockwise and got a new bite. Then tried adjusting the primary tension to 61.5hz. Couldn't do it. Something else is up at this point.

I will perform a full diagnostic next trip out.
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d11gnccer
SkipD;8562 wrote:
That's a case where I would feel obligated to let the electrical inspector know what was discovered. Though I am not an attorney, I feel that I may be held partially liable if the house burned down and I had not reported the total disregard for following codes but others discovered that I had known of the situation.
It's documented on a work order and we have a quote out to correct the problem. The homeowner is fully aware that he is not up to code and the risk of not being covered by insurance/manslaughter charges of backfeeding to utility lines.
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Skip Douglas SkipD
d11gnccer;8572 wrote:
It's documented on a work order and we have a quote out to correct the problem. The homeowner is fully aware that he is not up to code and the risk of not being covered by insurance/manslaughter charges of backfeeding to utility lines.
That's good to hear.

I surely do hope that the homeowner takes the proper action.
Skip Douglas
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scoot
Have you checked the throttle body? I have had the erratic hz at no load also,and found that the "stamped" part of the the body to be loose just a bit causing the fluctuation. If this is even a little loose will cause problem, and if the unit has been running like this you will have to reset the govener shaft and adjust speed per manual
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