MEP generator sizing for starting 10hp elec motors

[FFJR]

I'm evaluating getting a generator to run a grain bin that I'm putting up this summer vs having REC drop electric for me - getting a quote from them this next week I hope.
Just considering the option that a GL MEP 004/005?? might be viable option to power the site instead (no recuring monthly charges).

Loads: 10 hp centrifugal fan - would be running by itself for the most part other then maybe some block heaters at the same time I think during harvest. the 10 hp fan could be ordered as a single or three phase fan. The other loads would be a 7.5 hp unload auger and beyond that maybe a 10 hp electric unload belt that could run at the same time - but that could be a pto powered unit potentially.

Run time continuous would be 7-10 days straight right at harvest to initally dry, otherwise some intermitant times during the year spring and fall for block heaters and the unload.

Any input as to a MEP 004 15KW being large enough? or would a 005 / 30KW be the need? Also - any ideas on fuel consumption for these motors?

other question would be - if wired for three phase for smaller wires, cheaper motor, easier starting - would the other (smaller) 7.5 or 5hp motors need to be 3phase as well? or could they be run single with the generator? Or would that be too unbalanced ? I assume a person could pull 5kw or under single phase while it was setup for 3phase without any issue?

Thanks for your input and knowledge.

 

[gimpyrobb]

I would first look at current in-rush. The amperage to start a motor is often high, then settles down to the rated amp draw. You can size the genset from those numbers.

 

[Isaac-1]

Starting sequence on the motors may factor in also, are they staggered, would multiple ones start at the same time, is there a lot of stopping and starting on any of them, etc.

 

[FFJR]

The largest (10hp) would / can be started first and would typically run steady for a few days at a time. The smaller loads (5 or 7.5hp) would start and stop in about 15 minute time frames, but after stopping typically wouldn't start up again for at least an hour (loadout). I really don't forsee the 10 hp being used at the same time as the 5 or 7.5 - what I would see with it would be block heaters overnight added on and a few lights around the area is about it

 

[bchauvette]

follow

 

[FFJR]

I may be able to get that info from a manufacturer for the 10hp centrifugal fan this week at a trade/farm show I'm attending - otherwise right now I don't have any motors yet - this is all going to be new purchases for the project. Right now I'm just sizing the equipment on the bin and their brochures just give me the fan size and hp for a given airflow rating.

 

[dependable]

I'm guessing the 005 would be a better choice. If the 004 worked, you would still have to pay more attention to start up sequence.

 

[Isaac-1]

3 phase is also MUCH easier starting than single phase when it comes to inrush, and while I am not going to say that a MEP-004a could not handle it, I will say that there are potential combination conditions here that would put things into the questionable realm. Particularly without having detailed numbers on the starting and running load of the 3 motors, also keep in mind those incidental loads like heaters and lights can add up fast.

The typical 75% running load of motors these sizes are:

5HP = 3.4KW
7.5HP = 5KW
10HP = 6.3KW

So even if it does start them all three running at once is going to put you at 14.7KW, and this does not count lights, etc. and again assumes each is at 75% load.

Having said that if the two larger ones were 3 phase, and if you could assure that the 10HP would not be running while the other two were running, and the start up for the 7.5HP and 5HP were staggered then I would say that a MEP-004a in good running condition could handle this with no problem. This assume the starting loads on the motors are typical code H or lower motors (typically blowers and such are code F). It is just once you add that 10HP / 6.3KW base load on top that things might get tricky.

Ike

p.s. I would also worry about running a 30KW MEP-005a for long periods of time with only a 6.3KW load on in it due to potential for wet stacking, these diesel generators should always be ran with a base load of about 50% or more.

Sorry I think I misread that as 3 motors running with 10, 7.5 and 5 hp not 10 + 7.5 OR 5HP if it were the later two then if they were both 3 phase you should have no problems.

 

[FFJR]

At this point, I can't see anytime when the 10 hp fan would be running at the same time as I'm loading out (useing the smaller motors). If that day comes it's probably due to an expansion there and I'd be looking to put in grid power at that point. Two 1500 watt block heaters and a pair of yard lights would be the accessory loads that I anticipate unless I needed to run some small power tools for a repair job.

Was thinking the 004 would be a nice sized unit to have as a farmstead backup as well, whereas the 005 would be a bit overkill and burn more fuel due to it's size alone. Right now I have a gas 13hp honda powered 6.5kw genset I use for mobile power to the farm and as a backup to the house- but the one time I've used it on the house I've really had to mange the load here flipping breakers on and off to keep it balanced.

If those motors are genuine WHITE motors from the White Farm Equipment company (bought out by Agco which I've seen on the side of newer gensets) those may have been made right down the road back in the 80's about 45 miles away from me. I always assumed they were, but didn't know if they had other plants where these were made vs the tractor motors.

 

[Jimc]

The equipment and motors themselves will play a factor. For instance i have an 003a and in my shop i have a 3hp tubaxial fan and a 7.5hp compressor. The fan is actually harder to start than the compressor. My gen will run both at the same time but the fan has to come on first. For some reason the fan is just hard to get going. Could be motor design. Small start cap, who knows. 3ph will definitely be bettor for you though.

 

[FFJR]

Is it wrong of me to want the REC to come in with a outrageous bid on putting in the transformer and service so I have an excuse to go looking on G.L. for my second purchase???

Thanks to all for the help, I believe that the 004 15KW will be a good match for the system I'm building, and also give me a better backup then the gas genset I have now for winter use around the house (like the current blizzard we're having this afternoon - no ice on the lines, so we just hope the hold up to trees hitting them now).

Here's a pic of my first G.L. purchase. Use it as a service trailer at the farm, 100 gal of diesel, northern tool / honda genset, older 15 gallon air compressor, and other "stuff". pic shows it during a spring/summer storm that rolled through and we were out for about 12 hours. A 15KW would be a lot nicer fit though, wouldn't have to manage loads, and I've always got diesel around for the tractors.

 

[storeman]

Handy rig.

 

[Triple Jim]

3 phase is also MUCH easier starting than single phase when it comes to inrush...

I'm not disagreeing Ike, but not long ago I measured the starting current of three centrifugal blowers. They had quite a bit of inertia, so were slow to start, and the slo-blo fuses that were chosen were blowing at startup. The blowers had 5, 10, and 15 hp Baldor motors, and were running on 208V 3ϕ. I used an Amprobe clamp-on ammeter, and the slow startup allowed me to easily watch the current. I was completely surprised when I measured a full ten times the running current, and this held for all three motors. Of course that current tapered down as the motors sped up. I chose some physically larger slo-blo fuses that were designed for this kind of load, and they worked fine, but if that centrifugal fan of FFJR's is anything like the ones I worked with, he'll need more generator than an 004A, or some sort of soft-start equipment to limit the starting current.

 

[NEIOWA]

Is it wrong of me to want the REC to come in with a outrageous bid on putting in the transformer and service so I have an excuse to go looking on G.L. for my second purchase???

Thanks to all for the help, I believe that the 004 15KW will be a good match for the system I'm building, and also give me a better backup then the gas genset I have now for winter use around the house (like the current blizzard we're having this afternoon - no ice on the lines, so we just hope the hold up to trees hitting them now).
...

Yeah nice night. TO STAY HOME. I do NOT want to take a fire truck out tonight to rescue any morons. You must be pretty near me (East of Oelwein). Have a MEP004 could make available for a test of your theory/plan. And a bunch of new old stock civilian 3ph motors that are for sale.

 

[FFJR]

I just came in from the shop and heard on the county freq Rockwell get called out for a medical - stomach pain 20yrold. We had a medical last night at 3AM, was nice out then - just fresh snow and no wind. I'll keep your offer in mind as I get the final sizing / layout figured out as to what I need for the unload / powersweep.

 

[PeterD]

FWIW, I understand that the 004 has a good 'surge' rating. I can't remember what it is (and since I'm in the hospital, can't get at my manuals) but it probably will work if one is careful about starting one at a time.

 

[Isaac-1]

Peter, hope you are better soon, I know what it is like posting from a hospital bed.