200KW generator rather than store bought power, what do I need to know?

[Tyler d4c]

On a note of the millitary gennys the 2 ive owned where able to be wired for 480.

 

[MarshallPowerGen]

Here is one that seems to fit my requirements.

https://www.machinerytrader.com/listing/for-sale/255972137/2002-spectrum-255-kw-stationary-generators-power-systems

From the Spec number, that should be basically a rebranded Kohler 250RZD/RZDB with a slightly reorganized DEC-3 16 Light Controller.

Gen-end and controller parts are still all available through Kohler (or Rehko now). Also can updated to a Flight Systems controller pretty easily (or ordered as a plug and play through Davidson Sales).

 

[terex herder]

Marshall, I don't find anything via gogl about flight systems controller or davidson sales. Is this something that would improve the responsiveness of the generator? Was Spectrum a reseller that is no longer around?

 

[DDoug]

Natty gas doesn't have the power of diesel for motors . Gas is good for light loads not motors .
We do BIG gen sets and I only use cat . The one we just did in Oklahoma Was 3000 amps at 480 volt . The price of them will make you poop . They aint cheap not to mention the tornado requirements you will need to comply with .

Interesting, I always thought KW is KW no matter the prime mover.

 

[Willie B]

Interesting, I always thought KW is KW no matter the prime mover.

In the 10-30 KW ranges, the same machine might have a KW rating for natural gas, another for propane. Propane makes an engine more powerful than it'd be on natural gas. I think about 9% difference.
I presume the gas fueled engines need to be bigger than diesels for the same KW rating.

 

[Nige]

According to the numbers I have available a natural gas powered genset in the 200-250 eKw output range will be anything from 20-40% less fuel efficient than the equivalent diesel-powered set, all other factors being equal. Maybe @Catsparky1 can shed more light.

Diesel Generator Fuel Consumption Chart by kW | Gallons/Hour

Fuel consumption charts for diesel generators 20 kW to 4000 kW. Gallons per hour at 25%, 50%, 75%, 100% load. Plan fuel tank sizing and operational costs.

generatorsource.com

 

[Nige]

I presume the gas fueled engines need to be bigger than diesels for the same KW rating.

I wouldn't say that is necessarily the case. There will be ways of turning up the wick on any model of engine to make it produce the required power from an energy-poor fuel. All down to the control of fuelling and cramming sufficient air into it.

 

[DDoug]

Either way, is not a 200 kw genset a 200 kw genset, regardless of prime mover ?
and a 200 kw genset should run whatever loads up to 200 kw ?

The local phone company had a large backup genset in the basement powered by a gas turbine.

 

[Willie B]

I wouldn't say that is necessarily the case. There will be ways of turning up the wick on any model of engine to make it produce the required power from an energy-poor fuel. All down to the control of fuelling and cramming sufficient air into it.

I guess bigger was a poor choice of words. In Generac home standby machines the less costly models are the same machine, you only adjust the orfice from natural gas to propane. In some models they rate output lower for natural gas. Other models have an engine with adequate power to run the alternator at full rating.

 

[Nige]

Either way, is not a 200 kw genset a 200 kw genset, regardless of prime mover ?
and a 200 kw genset should run whatever loads up to 200 kw ?

Electrically I would agree with you, it’s simply the amount of fuel required to produce whatever quantity of power that comes out of the generator end.

 

[terex herder]

Nige, I agree with you on the better thermal efficiency of diesel engines over natural gas. But I'm looking at the economic efficiency. Using the table you linked, (thanks for that) a 250kw at 75% load the cost per hour of the diesel would be $58.40 at $4.30/gallon. Natural gas would be $18.51 at $7.20/mcf.

Based on Catsparky1 post, I think a 250 kw is probably a better choice than a 200 kw.

 

[Nige]

Based on Catsparky1 post, I think a 250 kw is probably a better choice than a 200 kw.

Based on your OP I also thought that. TBH if the right set came up for sale you could probably go as big as 300 eKW and still be winning. The load on it would be adequate to keep the engine clean internally. I've seen the results of too many sets that were run at very low loads and it's not pretty.

 

[Welder Dave]

The engine is a DD 60 series not a screaming 2 stroke. Arguably one of the best engines ever made according to Truck Shop.

 

[MarshallPowerGen]

Marshall, I don't find anything via gogl about flight systems controller or davidson sales. Is this something that would improve the responsiveness of the generator? Was Spectrum a reseller that is no longer around?

Sorry, I meant a Deep Sea controller retrofit, not Flight Systems.

The Kohler DEC3 is a good controller, but when the boards start having issues they can be a pain to properly diagnose and are pricey to replace. Many elect to update to a newer controller and aftermarket AVR that's easy to plug into and program versus patching up peices at a time.

Davidson Sales Co

Davidson Sales Company is a factory representative, stocking distributor and manufacturer serving the power generation market.

www.davidsonsales.com

That unit was built by Kohler for MTU/Detroit Spectrum. I really don't know the history of their relationship.

EDIT: Thank you Wikipedia
"In 2000, DaimlerChrysler acquired the Detroit Diesel Corporation and placed its on-highway division under Daimler Trucks North America. The off-highway division was placed under MTU Friedrichshafen to form MTU America. Detroit Diesel branding has been maintained by DTNA and MTU America."

 

[JBrady]

Bigger nat gas gensets are all the rage right now. Just look at Caterpillar's stock price over the last 18 months. Data centers are gobbling up everything they can get their hands on. A diesel genset will handle power spikes (transient loads) better than a nat gas engine, but power wise they will have the same rating. A 3512 B/C/E genset has the same power rating as its G3512 cousin. There is a guy in western Oklahoma that has some contract with major retailers like Wal Mart and often sells their emergency generators on Marketplace.

Another suggestion would be to use a manual transfer switch on your install so if you ever need to go back to grid power, you can just pay the bill and have them set your meter.

Just to give you a reference point, there is a 200kw diesel generator (200 hours), sound enclosure, and ASCO 300 auto transfer switch for sale near Tulsa, OK for $25,000.

 

[terex herder]

Thanks everyone for their help and insight. I may not be much smarter, but I am less uneducated.

In reading some specs I found the note "derate 7% per 1,000' elevation above 600'. (I am at 1300', so 5% derate.) Maximum rated altitude 5,000'." That is a far more severe altitude derate than I have encountered in other applications. ISTR we used to figure 4%/1000' for spark ignition non-forced induction, but there was a slightly offsetting vehicle drag reduction of 2%/1000'.

 

[Nige]

That’s fine, but do those same numbers hold true for a turbocharged engine which I assume it will be if you are looking at a 250eKW generator set.