Diesel genset question

[dicer]

Genset in question has a voltage regulator that is very rusty and corroded. Want to run the engine. Is it best to disconnect all the connections to the vr? Don't want to do something to smoke the generator. I think its a cat scrc 140KW.

 

[waross]

On a set that is in unknown condition I would be more worried about winding damage. By all means disconnect the AVR. I have seen mre than one set started without a check of the winding insulation resistance go up in smoke. Well, I didn't actually see the smoke. They called me after all the magic smoke was gone.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[TheBlacksmith]

I would. Is this an emergency genset? They are generally set up to automatically flash the field and come up to voltage. If the regulator sticks it could overvolt the generator. Just make sure (schematic, wire trace), that the set doesn't utilize output frequency as a rpm signal.

 

[catserveng]

Maybe an SRCR tail end? By all means, disconnect sensing and field output, on old SRCR regulators the buildup relay would hang up, causing VERY high output voltage. Also lift the brushes off the slip rings, I've seem sets that have sat a long time, try to start and the brush rigging tears off because the brushes were stuck to the slip rings.

The regulator is likely DOA, and there is no CAT supplied replacement, if you're looking to revive the set, PowerTronics has replacement regulators and great technical support. I would strongly recommend a megger test and a close look at the rotor before starting, and your best long term solution may be a replacement tail end.

Hope that helps, Mike L.

 

[dicer]

catserveng, "a close look at the rotor" what am I looking for?
I had motored the engine many months ago, with the starter, after doing an oil change and prelube, with no injectors in, excellent oil pressure. The regulator looks like it would be an easy fix, all simple components, its just a rusty mess.
There is no electronic control of rpm on this that I can see. Just a mechanical governor.

 

[catserveng]

On an SRCR generator that has sat for some time, corrosion on the rotor could be a problem, caused tracking and voltage stability problems. Of course most of those units were in the oil fields, not well protected (ok, not protected at all).

A quick megger test of the rotor at 250 VDC, should be above 10 megohms. a visual inspection, may sure the coating is sound, not flaking, and that the slip rings don't have huge pits if it sat in one position and the brushes got moisture under them and corroded the slip rings.

The regulators were tough and reliable, but no parts availability for a long time now, some items are still available, but not usually what you need. Whenever I deal with one of these units these days I just buy an aftermarket regulator, if time is not an issue you may be able to get it working with what is there. Not likely your CAT dealer can help, unless you're near the oil patch, last dealer guy I knew of who was commfortable with them was in Midland.

That vintage unit would have minimum electric controls, if it has an overspeed/crank terminate switch it will be the Synchro Start centrifigul switch type, unless it got retrofitted.

At that output I'm guessing a D333 is the prime mover?

Mike L.

 

[dicer]

I checked the plate, its 135kw 3306. Its on the list of projects to do.