MEP-803A Starting kVa capacity

[jaxbill]

Hello, I read through the TM but don't see a listing for the starting kVa capacity. I believe the normal output can exceed 10kW a bit but have no idea what it can do for starting motors/compressors.

Thanks

 

[Light in the Dark]

803A can output up to roughly 15kw (about 62A)

 

[jaxbill]

Is that the highest it goes for quick spikes accounting for the normal voltage drop?

I was looking at a spec sheet for an air cooled LP 20kW generator and the "Peak Motor Starting kVa (assuming 35% voltage dip) is 41 kVa for 240 V".

I always thought you get a significant bump over the standby rating for starting motors.

 

[DieselAddict]

That's a difficult to answer question. Many variables to understand. From a practical standpoint here are my estimates based on what I've learned over the years. This assumes single phase cap start.

Fractional to 2HP - no problem. Will start reliably.

2.5HP - 5HP - 50/50. Above 3HP you need to have your crap together to get a reliable start. Unloader valves, compressor clutches, hard start caps. Some 5HP motors will not start on an 803 without instantly tripping the breaker even with no load. You won't know till you try. Sorry.

Over 5HP.. not likely.

 

[jaxbill]

That's a difficult to answer question. Many variables to understand. From a practical standpoint here are my estimates based on what I've learned over the years. This assumes single phase cap start.

Fractional to 2HP - no problem. Will start reliably.

2.5HP - 5HP - 50/50. Above 3HP you need to have your crap together to get a reliable start. Unloader valves, compressor clutches, hard start caps. Some 5HP motors will not start on an 803 without instantly tripping the breaker even with no load. You won't know till you try. Sorry.

Over 5HP.. not likely.

Understood. Appreciate the info.

 

[Suprman]

The 803a will not start a fdecu 5ton ac unit where a 804a 15k gen will start it. I believe the ac unit is rated for 15k startup. Other than the start up draw, I believe the 10k would handle the running load of the ac. Once you get over 10k draw on the 803a I find you can load it 12-14kw but you have to step it. They don't like going from no load to 13k load.

 

[jaxbill]

The 803a will not start a fdecu 5ton ac unit where a 804a 15k gen will start it.

I had no idea the 804A even existed. Thanks for this.

 

[Suprman]

804a is 3 phase output only though.

 

[jaxbill]

804a is 3 phase output only though.

Oh crap and my first search of Craigslist turned up a pretty good looking unit. Thanks!

 

[Suprman]

If you have to have single phase, 10kw is it for military gens. Plenty of larger civilian models out there that have phase switches though. If you are running 120/208 3 phase equipment you can tap off one or two 120 legs to neutral for small amounts of single phase power but you won't get 240.

 

[jaxbill]

I assume there's no work-around or way to re-configure it?

 

[Suprman]

803a can do 120, 120/240 or 120/208 3ph. 804a is 120/208 or 240/416 both 3ph. You could tap a leg in 240/416 mode and get 240 single phase. You would only be able to use at best 1/3 of the generators capacity and it would be an unbalanced load. And in 240/416 you can't get 120.

 

[jaxbill]

Ok, now it makes perfect sense and is easier to understand than anything I googled so far.

 

[Suprman]

If you are only trying to run equipment, sometimes the equipment can be reconfigured to run on 3 phase. I have my plasma cutter set up like that. Run it off an 803. Motors can be replaced with 3 phase ones. If you want something for household backup power only then single phase is the way to go.

 

[155mm]

... If you want something for household backup power only then single phase is the way to go.

Single phase jenny's are the easiest way to go, if he needs more than the 10kw to start up something, then the 15 would be 'the way to go' due to necessity. I have only found a couple older AC units that are not compatible with 208, but they were in the scrap metal. Even our new Kenmore dryer is 208 compatible. Check your household equipment for compatibility, almost all of it will be compatable.
OP didn't state what his intentions for the jenny were, if its for backup, just use the 804, as needed, then when the emergency passes load test it to clean any unwanted's out.

https://www.steelsoldiers.com/showthread.php?167498-Wife-is-now-a-green-iron-believer

only pulled 2 legs off of the 3 for 6 days, no know issues have showed up.

 

[robertsears1]

It has been my experience that my 804a will usually not start my FEDCU-5s without tripping the short circuit light or tripping the main breaker, once in a blue moon, it will actually get the compressor running. My 804b will start them (actually get the compressor going) about 25% of the time without kicking out the main breaker due to the amount of current needed, it does not indicate a short like the 804a. I have five of the FDECU-5s and it is consistent from used ones to never put into service with the plug still in bubble wrap ones. I think my 804a needs to have the sensitivity of the short circuit alarm (could be the main breaker) adjusted and I remember reading something about that recently, need to investigate further. The FDECU-5 needs 60 amps while the 804 only puts out 52 best I remember. Granted, 10.4 kW is drawn by the two heat strips alone, but I have found getting past the big pull of the compressor start with the strips off is my biggest problem. With both fans and both heat strips on in the maintenance mode, it pulls 80% on the 804s so I use it as a load bank. Again, this is consistent across my fleet of FDECUs (I have five for some reason) Your mileage may vary.

I just brought home a fueling apparatus with a civilian 60kW 250 amp generator. I plan to try it on my FDECUs once I get it running and it warms up some. Robert

 

[CT-Mike]

804a is 3 phase output only though.

The older MEP-004 is a 15 KW unit with a 12-wine generator head. As such it can be rewired into low zigzag mode to give you a balanced single phase output. Search for Sewerzuk’s post on here for info on how to perform the mod.

 

[jaxbill]

The older MEP-004 is a 15 KW unit with a 12-wine generator head. As such it can be rewired into low zigzag mode to give you a balanced single phase output. Search for Sewerzuk’s post on here for info on how to perform the mod.

Thanks for the tip on where to search. Great threads and videos.

Looks like the 804 is 10 wire and can't be modified like the 004. But, I do need to see if my 240V loads are rated for 208V. If I understand correctly, I can use 2 legs, run the unit in 120/208V mode, and get 10kW rated capacity plus the normal excess capacity of a MEP, which could get you to more than a MEP-803A at least before it overloads for motor starting. However, I don't know how much more and if it's enough to deal with an 804. I will keep researching.

The seller of the MEP-804A is saying 15kw is reasonable to expect even on single phase. I imagine like all MEPs it would get much more than the rated 15kW using 3ph.

 

[Suprman]

You won't get 15kw out of an 804a single phase. It will give you 120 from each of the 3 legs to neutral and 208 leg to leg. You couldn't wire it to your house panel and just switch over. You need a single phase gen. Find one in the size you need. Dosnt have to be military surplus to do the job. I don't advise going with an older model 004a. As they are older parts are becoming harder to find. And they are loud.

 

[jaxbill]

Ok, I still might be able to make a 803 work. Added one of those consumer load monitoring products to main panel today. Need to get some data. Also haven't installed the hard start kit on the heat pump yet.