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

[terex herder]

I am working on a grain storage and handling complex. Due to the demand charges the power company bill is obscene. Last month I paid $460. for $17 worth of electricity. Seasonal use facility, mostly September through December. Motor load will be a 60hp, 2x 30hp, and sometimes 1 or 2 20hp as well. All will start unloaded, and in sequence, never simultaneously.

I have natural gas at the site, had a 10,000,000 btu burner previous, so am thinking of natural gas for power. It looks like natural gas is about 1/3 the price of diesel right now.

So I am looking for a used generator in the 175 to 250 kw range, 480V 3 phase. What things do I need to know, any things to stay far away from, what would be good? Any knowledge or observations that could be helpful?

 

[Simon C]

You are talking about 100HP of electrical load, The question is will the 30 HP be engaged before or after 2- 20HP motors. The inrush current can be 6 times the running amperage on 600 volt units. It would be just as high from what I know on 480 volt units. If the generator is too weak there could be issues.
Lots will depend on if it is automatic load control or operator adjusted frequency.
There is lots of things to consider when generators are being selected.
Simon C

 

[Simon C]

Forgot to mention that $1500 of electricity from Sept-Dec. is just small compared to a 250KW generator used. And used will mean some big dollars to repair at some point.
Simon C

 

[terex herder]

Electric company demand charge with new equipment will jump to $1,000 to $1500/month for a 12 month period, even with no electric usage. Actual power usage is small. I estimate 200-300 hours/year of run time.

 

[skyking1]

Genny makes sense under those circumstances. Mom and Pop crushers run those kinds of sequenced loads.
Might be nice to find one of those power trailers all set up and just make the few changes. I would think Tier 2 stuff out of California would be available now.
For those kinds of hours I would get a diesel and not bother with the NG.

 

[terex herder]

Today's prices for natural gas is $7.15/1,000ft3. 200kw full snort should be 2,583,000 btu/hr, or about $18.47/hr operating cost. Diesel, 14.5 gallon/hour. At $4.30/gallon, thats $62.35/hour. 200 hours, thats $8776 operating cost difference in favor of the natural gas.

 

[Catsparky1]

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 .

At 480 3 phase line to line voltage with all running you will need 261 kw .
I know you say they will never all run together but I've done this far too long to believe you . Not calling you a lair just from past experiences this is what I learned .

So 300 kw gen set new you are in the six figure range . 250 is the next size down and those can be towable . You would put quick disconnects on your electrical panel the genny already has them on it .

We are a design build contractor that does lots of BIG gen sets . hope that helps .

 

[DDoug]

Sept. thru December, might want to see if the heat thrown off can warm the shop as well.

 

[Joe H]

Look at Gov Surplus, gen sets are something the Army likes to dispose of frequently.

Here's a little one https://www.govplanet.com/jsp/s/ite...et&utm_medium=email&utm_campaign=GP-FA-061826

Joe H

 

[Simon C]

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 .

At 480 3 phase line to line voltage with all running you will need 261 kw .
I know you say they will never all run together but I've done this far too long to believe you . Not calling you a lair just from past experiences this is what I learned .

So 300 kw gen set new you are in the six figure range . 250 is the next size down and those can be towable . You would put quick disconnects on your electrical panel the genny already has them on it .

We are a design build contractor that does lots of BIG gen sets . hope that helps .

Have to agree with size, the question is how much is the budget and what will you get for it?
Simon C

 

[MarshallPowerGen]

You'd need to post up what you're checking out at auction or private sales to give you real world pros & cons (not links that would drive up the price, just model info).

Nat Gas at that kW is going to chew through some fuel. You'd likely be looking mostly at a PSI 10L-T or 11L, or some older Big Cam Cummins with the gasser head. There are other engines ran, but I'm not at my laptop right now.

 

[cfherrman]

Generators are very expensive unless you are getting close to max load, consider your load requirements and I would size multiple generators so you are getting your bang for your buck, also consider getting drives for your motors although they probably would be too expensive, but you could use small single phase generators and it would be overall cheaper

 

[cfherrman]

My cousin had a 855 genny, irc he said it was 20 gal/hr diesel

 

[crane operator]

We've dealt with some big crusher generators, and we actually just loaded up a big Cummins diesel a couple months ago. I think it was around $50,000 used. But the former owner had just put $25,000 into it with some repairs. It went to Louisiana.

I'll try to find out what the kw was on that unit.

 

[terex herder]

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

 

[Welder Dave]

That seems really cheap!

 

[Catsparky1]

could work well in your application.
Its a DD so if a twister gets it just follow the oil trail .
it will be really loud but you can get sound damping for it .
There is a company out of Washington state that does used and custom builds but I can't remember the name .

I do know they stand behind what they sell if that helps .

 

[Catsparky1]

Oh and one more thing . Don't matter the motor they all break . they do service and mantainance are key .
the motor doesn't matter the brand its what it spins that is going to fail first .

 

[Tyler d4c]

Like New Detroit Diesel 16V71T 450KW Diesel Generator Set - Depco Power Systems

www.depco.com

No mufflers either!

 

[Willie B]

I sell & install home standby generators. While I've been asked to price big machines, I've never sold one. I do from time to time work on them. Something to be VERY careful about is confirming you buy a machine you can configure to meet your power needs. Most large ones can be reconnected to choose your power choice, a few can't. I've gone to look at former military generators to find they are only 208/120. Others are 50 cycle, usually a manageable change.
Motors & other magnetic machines depend on "magnetic choke" to limit current. An across the line starter sends power to the motor. Magnetic field builds from 0% to 100%. At the instant it starts your magnetic field is zero. Starting current may be 700% to 1200% of running current. If it overloads the engine, it may slow the generator, lowering frequency, and voltage, as current spikes. A variety of failures can occur. Soft starters, or VFD controls can help. Be very sure your generator is big enough.