my experience with wet stacking

[Beerslayer]

When do you think the load should be cut in? Say, a certain time after there is oil pressure? Or later?

 

[PeterD]

When do you think the load should be cut in? Say, a certain time after there is oil pressure? Or later?

I always apply load as soon as the frequency is stable, the voltage is stable, and I've done a review of the engine gauges to ensure all are within normal limits. So about 10 seconds after I reset frequency (as my generator will startup with a slightly off frequency.) Once running for about 5 to 10 minutes, I recheck frequency, and readjust as it will be off as it warms up (not much, about 1 Hz or so.)

 

[sewerzuk]

When do you think the load should be cut in? Say, a certain time after there is oil pressure? Or later?

I typically give the set about a minute to run under no load to warm up, then a partial load for another minute or two to speed the warmup process, then 80-100% load.

 

[quickfarms]

My light trailer, like the ones found at construction sites, has 4 1000 watt lights on it that are powered by a 6kw generator. The designers engineered this unit with a 67% load. There are many of these out there that have run this way for thousands of hours.

I do not know what the magic number is but there needs to be a load.

 

[steelypip]

The short answer to the how much load question is 'enough to get everything hot.' A wally-world Chinese gasoline generator probably shouldn't be run sustained at rated output very long. I'd probably do the test run (30 min or so) at 2/3 rated load and do a 30-60 second full-load check just to make sure everything could cope, then back down to 20% load for a few minutes' cool down before shut off.

By comparison, the mil-spec generators are extremely under-rated. As sewerzuk's test case showed, the MEP-005A in good health was capable of pulling 166% of rated output. I haven't loaded my MEP-002A that hard, but I did have it reading 100% on the load meter with a pure-resistive load, which should be about 120% of rated load. I didn't have any more space heaters to load it with, so I don't know how much more was in the jar.

That said, wet stacking shouldn't be a problem even at 50% of rated load as long as the test run is long enough. My generator doesn't really start to get warm until it has run under load for half an hour or so. I'd say that the air-cooled diesels probably need to run an hour at a shot to get everything up to thermal equilibrium. I have not observed that the warm up happens a lot faster at 100% rated load than it does at 50% of rated, which suggests that the thermostat on the cooling tin is doing its job.

Probably the worst cases of wet-stacking I've ever heard of were on the British Rail Class 55 Deltic locomtives. There were two Napier Deltic engines in each one, and Brit Rail had trouble finding heavy enough trains to really work the engines. Combine that with a complicated and oily two-stroke diesel exhaust system and lots of engine idling, and you have a recipe for the famous 'Deltic exhaust collector drum fire' that resulted in quite a few of them going to the shop for repairs during their operational lives.

 

[Motorcar]

that Deltic is light duty stuff...watch this.

.[media]http://www.youtube.com/watch?v=GSJw8AhtdrA[/media]

 

[SouthwestUSA]

And all this time, I thought "wet stacking" had something to do with that TV show David Hasselhoff , was on called "Bay Watch."

Just goes to show how enlightened one can become by a daily dose of Steel Soldiers...

And this week, I get to pull maintenance on 5 MEP generators I have in the barn... Should be interesting to see what I have, but they were never owned by civilians...