Genset Power Quality Improvement?

[WQ9E]

As to my old genny, I was more amazed at how low the octane rating is for it. I guess the high compression/high octane/combustion phase hadn't kicked in back then. More of a 50s-60s thing?

I have a friend who collects and restores old IH "iron".  Attached is part of the spec sheet for some of their 1940s/early 50s era engines, use your PDF viewer to rotate it for easier viewing.  Note that even with the large displacement the HP rating is very low resulting mostly from low compression and low recommended RPM operation.  Realize the net HP rating from this era is inflated compared to how engine HP is measured today.  My friend also has an advertising sheet from the introduction of the blue diamond series engines with their 6.3 to 1 compression as a modern high compression engine. 

Now we have light truck diesel engines producing around 1 horsepower per cubic inch and naturally aspirated gasoline engines producing over 1.5 HP per cubic inch.  The gasoline engine in my 2008 CTS uses a 11.3 to 1 compression ratio but thanks to the wonders of direct injection recommended octane is 87.

Of course those engines probably won't still be operational 70 years in the future like many of their 1940s ancestors

[W1TAV]

Chris,

Welcome to my world of Generators and issues with the proliferation of switching power supplies. For what it is worth, I have been seeing and dealing with the effects of reactive power in building distribution systems since the mid 1980's. For the past 5 years I have been directly supporting the emergency power systems for some 3000 cellular phone sites and another 1000 or so commercial generators or as the NFPA calls them "Rotational Energy Converters"

1st, I too had one of the 1st generation energy saving washers. I could hear it on HF 200+ yards away from the house! Good luck with trapping the RF hash from yours.. I was never able to completely clean mine up until it went to the scarp yard 2 years ago!

As for your generator, look for a 0.5-1 KVA 240 Volt transformer and tie it into the mains at the generator. You will not be using the output.  This is a Poor Man's means of dealing with the reactive power that it being thrown back at the Gen-set from non-linear loads (switching Power Supplies)

The best way I have found to describe the issue as it relates to generators is a garden hose. When using a self-closing spray head, open and close it rapidly as the flow of water is cut of, it sends a wave of energy back into the house system, it doesn't take too long and your pipes are banging. that energy is now converted to a mechanical energy you can see and hear. 

In a generator that energy has to be absorbed in the windings, two things occur, 1) as the current returns, it is dissipated as heat effectively de-rating the the generator  2) As the generator tries to overcome the returning energy, it can exceed the available torque binging the unit to it's knees! I have seen Ford V10's driving an alternator rated for 60KW, unable to to hold an apparent power 25 KW load due to reactive power issues.  Using an (unconnected secondary)  transformer on the output may help absorb and dissipate as heat this retuning energy on you home gen-set. We have seen this done.

I am working on a presentation regrading this issue, I will likely post an overview as it's own subject here on AMfone.  In the meantime for those considering buying a generator I offer the following: (note, I have no horse in home generator race, the lines of generators I work with start in the range of 30KW on up to 1.2 meg)

For Rope Start Generators Beware of any rating for KW, in the last few years, we have been seeing "5500" watt generators being sold by Pep-boy and others that are truly 3800 watt units. This category includes many good brand names that are relabeled Chi-Com imports. However  new inverter generator sets seem to be a very good product.

For home installations, (8-18 KW) the Kohler home line of generators looks to the the best bang for your buck.  Generac is the worst  and supplies many otherwise good brand names such as Siemens  and CAT with their home line and smaller commercial generators. Onan is outstanding, however it comes at a price. Propane and Nat Gas are good Choices. Avoid (wet) gas at all cost.


I would have liked to have replied to this sooner, however my company is still pretty busy fueling  and servicing running generators in NYC, Long island and NJ.

Steve

[W4EWH]

Avoid (wet) gas at all cost.

I disagree: I have natural gas here to heat my home, but a NG-powered genset has disadvantages from my perspective. Consider:

• It would cost three to five times what my gas-powered set cost when installation and permit costs are included.
• Gasoline is available almost everywhere, at any time of the day or night.
• Using natural gas would tie the unit to one location:
  
  • It would prevent me from helping out other members of my family if need be. At least in my area, my sister is often out when I have power, and I want the option of loaning the set to her.
  • I would not be able to use the generator on Field Day or during EmCom events.

73,

Bill, W1AC

[W1TAV]

Bill,

I 100% agree with your thoughts on fuel.  It is when you cross over to full automatic operation and/or do not want to fuss with fuel and its inherent issues that  Propane and Nat gas systems come into play.  Personally I use gasoline, however I (Like am and sure yourself)  take all due precaution with treatment and long term storage of the equipment. We are in the minority, maybe not on this board, but certainly in the general  population. 

I also have a 30KW diesel, mainly because I can, however it makes no sense for me to maintain it as a backup gen set. It's there if I needed it, I know it will run on heating oil and I would likely only use it if I had to together with a few others homes and distribute some shared power in a long term event.   

All that said, my long term strategy for my home is solar/ wet battery storage feeding an automatic Grid/generator tied full sine wave inverter, backed up with a 7 KW (dry) gas unit, likely propane as I have a 500 LB tank now. Again in a long term event, move back to Gas or for a longer time outage go to the diesel.

The use of a solar / propane generator system for me is not a theory. I have built one up over the last 30 years for friend of mine in Maine. Last weekend I installed the latest offering from Outback for an inverter, we now have networked the PV Changer controller, inverter and generator. This is the 4th generation of inverter that we have used in his home since 1982. He is off the grid. It is all about life style and what we are willing to put up with. For the house in Maine, other then a concession to using a gas refrigerator and stove, they live with all of our modern appliances including a front loading washer. The trick here is energy conservancy and the elimination and control over parasitic loads. BTW, the main reason for the recent upgrade was the need for full sine wave power.  The controls on his central heating system have never played nicely with a modified (square) sine wave, this is now now longer an issues. We also now have seamless cut over from Generator back to battery.

I really need to start another thread on this.. Sorry for getting of track! 

[W2PFY]

What get me about these small generators is that they always use carburetors? I wish it was mandated that they have real fuel injection systems in them They do it on the Harley motorcycles  although they are much larger HP than most home style gen sets. Does anyone know of a single cylinder fuel injected gas engine? I think if they were fuel injected, the hours per gallon would increase and the engines might run smoother.

[W2VW]

Lookie. This unit comes with someone to help hook it up.

http://www.ebay.com/itm/US-Stock-16000W-Peak-8000W-Sine-Wave-Power-Inverter-12V-DC-110V-AC-Power-Tools-/181026317694?pt=US_Power_Inverters_&hash=item2a26026

[Opcom]

In TX natural gas or diesel is my choice. I would prefer natural gas for home power as it is on when the electricity goes out. I currently have diesel, but it is not as satisfactory any more due to it not being $2 per gallon any more, and having to immediately source fuel and immediately pay for it as opposed to the city gas which is independent of grid power and has a monthly bill.

The system is fully automatic and I have about 3 days of fuel here, a weeks worth offsite. The bio-adulterated diesel fuel sold now does not seem to last as long as old #2 diesel before getting nasty or creating new issues. The only non automatic thing is I have to run the generator once a month manually.

In Texas we do not not have the luxury of disregarding air conditioning, at least a small conditioned space for sleeping and/or for sick/old people is necessary. The houses are no longer built for easy cooling by open windows and do not have the old style high ceilings +high attic any more. Some older ones have large windows and an attic fan that draws air through the house.

I was under the impression that to convert a gasoline engine to natural gas, one has only to buy the appropriate carburetor, regulator, and valves or switches.

I was also told a diesel such as a naturally aspirated Perkins on the Mankato 40K set can not be converted to n. gas.

Before I was offered the 40KW Mankato 1800RPM diesel set + 175A Zenith automatic transfer switch all for $5K a few years ago, I was going to convert a Kohler3.5CM21  single cylinder 1800RPM 3.5KW generator to N. gas and set it up as a manual operation to run one a/c, the fridge, and a computer or radio. some juggling would be needed to run the washer and the dryer. That genset was very old at the time, but at 1800RPM it would have lasted another few decades!

I suspect that the 40K diesel wet-stacks on my load. I can only draw 11KW exclusive of transmitters. The usual power with the a/c on is about 6KW. In an emergency I would purposely draw much less, one big factor would be switching from central air to 1-2 smallish room a/c units making it 2-3KW.

There's a site where the guy used a stack of the old glass jar type of telephone company cells, 2V each, and is totally off the grid. But he has no furnace or a/c, and the rest is extremely basic. When the weather is bad he can run a 2KW generator to charge the system. That scheme might not work as well in the South, or with an oversized generator set.

The efficiencies are best at higher loads than smaller so when a large machine (considering the load) is involved, it should be run harder - so it would make more sense to run it at a more efficient point and store the remainder in batteries. Battery cost prevents that in a "Texas modern city house" situation if this is right:
30KW - 3KW load = 27KW
27KW * 24 hours -> batteries is 648KWH.
648KWH * 50% efficiency = 324KWH.
324KWH=108 hours at 3KW load, or 5 days.
but 648KWH of batteries at 12VDC is 29K amp-hours
29K amp-hours = 290 pcs. of 100AH AGM batteries
plus the sine wave grid-tie inverter cost, which needs to be a 20-30KVA size
Will install this when the check comes from the lotto...


I would not mind supplying neighbors off the Diesel set in an acute emergency, but quickly they are going to have to pay or barter due to fuel cost and limited resources, plain and simple. Just running something that size for the noise alone is a minimum of 1GPH.

This leads to the point that if generator sets are plentiful it might be better to have two, a small one and a large one, and use the proper one depending on the load.

There is also concern about the liabilities, but this was commented in previously.
Additionally, if things are real bad (lawless), criminals posing as looters may seek to storm the castle for their own comfort and operations. In this way a power system can become an attractive nuisance as well as create extra duties at night for the home owner.

just some opinions.

[Opcom]

Lookie. This unit comes with someone to help hook it up.

http://www.ebay.com/itm/US-Stock-16000W-Peak-8000W-Sine-Wave-Power-Inverter-12V-DC-110V-AC-Power-Tools-/181026317694?pt=US_Power_Inverters_&hash=item2a26026

I'm not sure I would trust that lady to do electrical work. Or does she just lie around and complain while you do the work, then demand to be paid?

[Opcom]

As to my old genny, I was more amazed at how low the octane rating is for it. I guess the high compression/high octane/combustion phase hadn't kicked in back then. More of a 50s-60s thing?

I have a friend who collects and restores old IH "iron".  Attached is part of the spec sheet for some of their 1940s/early 50s era engines, use your PDF viewer to rotate it for easier viewing.  Note that even with the large displacement the HP rating is very low resulting mostly from low compression and low recommended RPM operation.  Realize the net HP rating from this era is inflated compared to how engine HP is measured today.  My friend also has an advertising sheet from the introduction of the blue diamond series engines with their 6.3 to 1 compression as a modern high compression engine. 

Now we have light truck diesel engines producing around 1 horsepower per cubic inch and naturally aspirated gasoline engines producing over 1.5 HP per cubic inch.  The gasoline engine in my 2008 CTS uses a 11.3 to 1 compression ratio but thanks to the wonders of direct injection recommended octane is 87.

Of course those engines probably won't still be operational 70 years in the future like many of their 1940s ancestors

There is a quite old and very big stationary straight six Allis Chalmers at a private farm in Gainesville TX. It is inside a barn and was used to roll grain IIRC. It's not in use because it blew a head gasket, otherwise was running. I hope someone can rescue it. I think it is the 6138 or similar, 800+ cubic inches, gasoline.

[W2PFY]

Bill said

I would not be able to use the generator on Field Day or during EmCom events.

You just need a long hose

[WQ9E]

I suspect that the 40K diesel wet-stacks on my load. I can only draw 11KW exclusive of transmitters. The usual power with the a/c on is about 6KW. In an emergency I would purposely draw much less, one big factor would be switching from central air to 1-2 smallish room a/c units making it 2-3KW.

Running sustained at only 2-3KW you are almost sure to run into problems with too low cylinder temperature, especially if your power outage occurs during low ambient temperature.  Some of the modern diesel engines with variable exhaust vanes in the turbocharger use them to restrict exhaust flow to increase engine temperature under low load operation.  You might be able to experiment with an exhaust restriction system for your genset but of course you are giving up efficiency to generate this additional heat.  The starting point would be to install an accurate EGT gauge to see where your set is operating under light loads and how readily it responds to increased exhaust restriction.  If your injection system is not operating as well as designed this will further increase the problem.