Folks,

We're setting up a fancy data center, and part of it is having backup power. I got to see the generators fired up and running today. WOW is all I can say. I talked with the CAT maintenance person. Here are some of the specs (if I remember correctly)..

V-12 Cats, about 1500+ HP each (we have 2 + an empty bay for a third)
each produces somewhere around 1.5 Megawatts of power
80 gallons of oil per oil change
Dual 6000 gallon fuel tanks, switchable, with 3 filters per line

now for the real fun!

they are preheated to 180* 24x7

startup to full power in ....... 9 seconds.

We were in a hurry to get this data center setup so we "bought up" to get an earlier delivery. These are way oversized, but were at the right price.

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Those are cool standby units. I work in nuclear power stations, they also use diesel-generators for standby power, normally two or three units between 2 and 4 MWE each. It's normal to pre-hear the jacket water to allow them to be loaded immediately. If you happen to be standing next to one when it starts, it will get your attention.

A few years ago I got to see the emergency generator at one of our local hospitals; it's smaller but similar in that it is also pre-heated to start quickly.

What do you have to cover the first nine seconds until the generators are up?

How often do they run the cats, for how long each time, and do they put a load on the motors or just let them idle? What about oil changes? Do they rotate out the fuel or treat it to prevent problems?

I have heard quite a few horror stories associated with the 1989 Loma Prieta earthquake in northern California. One hospital's generator died after ten minutes (water in the diesel fuel...) and they were dead in the water for several hours. Turns out the maintenance people ran the generators once a month for ten minutes.....

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

The big diesels are always impressive to see. We just had a 2 MW portable unit @ work when our substation blew. We used it to backfeed an on site transformer to power the plant, syncronized with our cogen plant (which is too small to carry full plant load). It was mounted in a custom built 40' box van 3 axle trailer. Even at partial load, it was swallowing over 800 gallons of diesel per day....at todays fuel prices....owwwiieeee!!!!!

I forgot to sneak a camera in & get pics of it..dammit...

I had some concerns of their methods as well, as they were essentially powering up a 12.5kv system thru a 480v secondary winding, with no way of detecting shorts or protecting the 12.5kv side.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

That does sound a little shaky, I assume it was an ungrounded system running without ground detection? Was this a temporary setup? Also, 2MWe at 480V is a LOT of current.

What do these things use to start? Hydraulic accumulators?

I spent a year on a working boat that had 2-12/71s for motive power, and 2 4/71s running generators. They used accumulators, which was great as long as they fired right up, but a pain to pump back up by hand if there was a problem.

I can't imagine the starter motor that would be required to burp over 1500 horses .....

I think for a lot of generators, the alternator/generator is coupled to the end of the driveshaft...I know in some diesel locomotives using electric motors, they just turn the alternator bolted to the end of the crank into a giant motors that turns the engine until it starts directly.

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1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER

A lot of standby diesels use air start motors to spin the flywheel, usually 4 air motors driven by 200-250 psig air. The air tanks are kept charged with compressors and have enough capacity for several starts. You can't motor the generator unless you have other power available.

Large marine diesels usually use "air starters" which will give you quite a "start" if your standing near by and dont know the engineer is about ready to "lite her off'

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I missed the moment of startup, but each generator had 4 large batteries tied to it. Each battery was about a foot wide, by a foot deep by 2 feet long. I'll ask next time I see them.

The cat guy said they did an 8 hour full load burn in on installation. They run the generators about 30 minutes a month, with maybe a 50% load.

We have about an hour of battery backup to bridge getting the generators up.

I may offer to burn off some of that "old" diesel sitting in the tanks. 8~)

Last place i worked that had big Cat generators,399s and 3412s each engine had 2 mt40 Delco starters.They did not start instantly as when you pushed the start switch it activated an oil pump and the starters did not crank until the oil pressure was up.We did have some smaller John Deere units 250kw that started and went online so quick i often wondered how long they could last,they were not heated oil or coolant. Don

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles

Supposidly CAT makes the best generators out their. I'm glad to see an American company doing so well.

Usualy the big engines like that have air starters.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Yeah, it's just 3 phase pole & underground wiring throughout the plant, normally fed thru our substation with a combination of PG&E & our cogen. The sub is the only link point to the system. What they did was a temporary setup just to get the plant back running to minimize production loss. The sub had a catastrophic failure on the high side (PG&E fed 115kv) resulting in the explosion of a gas filled motorized safety switch which had somehow gone to ground (quite impressive porcelain schrapnel bomb) I was just in there a few minutes before it went inspecting why it had tripped, had seen nothing evident. I can only guess it was either low on sulfur hexafluoride gas (which should only affect arcing it during operation of the switch though), or more likely the porcelain insulator(s) had developed hairline cracks in the coating and allowed moisture to seep in, creating enough potential. It was a very windy rainy day, & I had noted afterward that the stand had never been anchored down, so it relied on the buswork tubes to keep it upright, which could stress the insulators. We had to de energize the whole sub to make repairs and check it all out, and all of the safety paddles and monitoring equipment were in there. They got the idea to get that 2mw genset in and backfeed the transformer meantime, except that all the line safeties were all now out of the picture with the sub offline. They tied 5 mcm 500 cables to each phase of the genset and averaged 4000 or so amps of feed into that secondary (with the cogen synched online). That poor old transformer is tough.
The genset had dual electric starters, hit the start cycle button and it did the rest. It was interesting to hear it winding up, you could hear each cylinder fire in a locomotive type rhythm until it slowly gained enough rpm, then the standby light would come on, and you close the main breaker, it would sync and lock in, the engine would rock the trailer and drop with load, them you hit the load cycle button, you'd hear the twin turbos kick in and feel the tone of the exhaust change to raw power, and it would come up to the load you dialed in. Wish I'd gotten the pics, I could almost crawl inside the air filters.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

Wow, that sound very scary. You are lucky that you were elsewhere when it went. I'm a mechanical guy, switchyards scare me.

It is a bit unnerving to look over the aftermath and think about having just stood there (8" 5lb chunks of jagged porcelain 50' away and shards everywhere). You have to keep reminding yourself of it working in there, it's just so quiet and innocent seeming normally until that split second when....sometimes and usually you'll hear noise beforehand, in this case, it just up and blew. The switch had tripped initially and the ground fault paddle was tripped, I and the maintenance head looked it over, found nothing, decided to re energize it thinking the storm had probably upset it, everything appeared to close normally, panel lights were normal, but no power to the substation control room, we looked it over, switches were closed, left the area and went to look for another problem somewhere, that's when it blew.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale