Cheap Generator Test Load 2

[itsmoked]

So I want to load a 30kW 3cyl Cat diesel generator that's been forced to dribble along at 1kW for a while.

It's a WYE generator (Whisper Gen) with 480V 50A 3ph, 208 125A 3ph, 120 (3 phases). I want to run the saltwater rheostat gambit that Bill et.al. are happy with.

But... In all those discussions I just always thought, in my head, about 1ph, not actually thinking about the 3ph situation. For three phase power, I take it you do the exact same thing as 1ph but you use 3 electrodes and keep them as physically similar as possible and uniformly spaced as possible. Correct?

What would be a reasonable run time and load percentage for a de-sooting?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[wayne440]

When the exhaust clears up and the outlet is dry (no sticky residue), I call it done. The last one I did took about an hour at 80% load. The saltwater deal sounds like a PITA, why not rent a couple of 10-15kw portable heaters? They should be available cheap this time of year.

 

[waross]

Hi Keith. I would use one plastic barrel per phase. Automotive leaf springs make good electrodes. I would try for at least 50% load, more is better.
If the set has been pumping oil, beware of the possibility of burning oil leaving the stack.
Be prepared to add a lot of water, several time a day.
I was able to set up one load bank on a concrete roof. Isolation by elevation.
24 hours may do it.
I usually only load bank when there is an oil pumping problem, generally with a new set.
I had to do a 5 day run with a 280 KW set or the supplier would void the warranty. A motor was started a few times a day that needed the full output of the set to start. Normal operating was about 20% of rating.
For oil pumping, a day or so if memory is accurate.

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

 

[catserveng]

Salt boxes do a great job, but require diligent attention. Have used them in many situations for years. That being said, now days would prefer a solution that doesn't require bare conductors in and near water, maybe too much 70E training lately.

A fairly inexpensive solution, in line with Wayne's idea,

http://www.sunbeltrentals.com/equipment/category.aspx?id=s234

A couple of 10 kW heaters at around $50/day would give you 2/3 rated load, should be enough to burn off the slobber. When I did this a lot found the rental yards were actually willing to deal a bit on heaters going out in the summer, not normally a time they rent and they seemed to be more flexible.

As to amount of time and load required, NA engines will usually clean up pretty nice with something above 30% rated load, at least in my experience, TA engines usually need something in the 65 to 75% load range to clean up nicely. A lot depends on vintage of engine, type of ring packs used, size of exhaust system, etc.

My own rule of thumb was that an engine stack should have a noticeable reduction in smoke within an hour, most units cleaned up within 2 hours, some really stubborn ones after 4. Likely if it doesn't clean up in 4 hours there are other problems, like the muffler coked up, exhaust manifolds plugged, turbo seals damaged, or major engine problems requiring repair. At least from what I've seen. Hope that helps.

Mike L.

Bill makes an excellent point about watching what comes out of the stack, having started a couple of small fires and one test resulting in a multiple engine and ladder company Fire Department callout downtown to a major city kinda drove that point home for me.

 

[itsmoked]

Thanks all. I'll check on heaters as that would surely be less messy. Thanks for the time/percent numbers and the burning oil-spew warning too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

Rent a light tower which comes with a generator and just use the lights as a load. The light energy is easier to dissipate than heat.

http://www.lighttower.net/30kw-light-towers.aspx

 

[sreid]

"Burners" for electric stoves are cheap high power resistors.

 

[oldfieldguy]

Visit your local HVAC contractor and get a few resistive heater elements form upgrades. I have gotten them for the asking. Used them to build a single phase resistive load bank, then used it mostly in DC applications for testing battery banks, but it also loads up for generator tests as well.

old field guy

 

[waross]

Hi Keith.
To clear up a discrepancy between catserveng's post and mine;
I was dealing with badly seated rings that were pumping oil, or making sure that the rings were seated to avoid future problems. That takes longer than burning off soot.
Thus the different load bank times.
If you are cleaning up soot deposits, then use Mikes recommendations.

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