MEP-802A electrical output hookup

[155mm]

If your battery bank is 24v, why not use a 24v generator?

 

[155mm]

4.2kw gasoline

Used 4.2kw 28vdc 150A Gasoline Generator Set by Continental Motors, Military Sur | eBay

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3kw

3KW, 28 V.DC. Generator set w/ 4A032 Miltary Standard 4 cyl air cooled Engine | eBay

Rope start but there is a place to mount a starter. Test run with low Hrs. Sold AS IS. or dc power off the grid.

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[sl33k3r]

I thought about something like those. But they are not as portable and efficient as my gas generators. It's nice to be able to pick mine up with one hand to put it in the truck. Plus, mine output 110 Volt for use in the field to operate small air compressor, saws, drills and if need be...lighting. The 28 VDC generators are not as efficient either. I can operate mine for up to 16 hours with a bit over a gallon of fuel. I average about 8 hours per gallon. Also, I find mine very quiet. As low as 47db for one and 57db for the other. They start very easy and one is even on wheels and has a extendable handle.

Even with poor sun in my area, I find that over the past three years that I don't run the generators that much to charge batteries. I have run them maybe 100 hours each winter the past two winters. Summertime they don't get ran at all since we get enough sun to keep the batteries topped off unless we decide to operate the electric cooking appliances a bit too often on cloudy days. Most often they are out in the field or in one of the out buildings. They are much more efficient than the larger generators and as I stated before, very portable. Ease to set in the back of the truck, on a wagon or trailer or in the back of the UTV.

 

[sl33k3r]

At my shop I believe I will be the only one working and maybe my wife. Shop lighting and small hand tools will be on battery. The wood shop's largest single tool is a planer @ 3 HP with a 1 HP vacuum system. The metal shops largest motor may be 5 HP. My air compressor will be a gasoline engine powered unit and will not have a electrical draw off shop or generator power. As long as I can start and run a 3 HP machine, while a 1 HP system is drawing vacuum or start a 5 HP motor without another load, I will be fine with a 802A.

To determine my requirements then, I need to know if the 802A will safely start a 5 HP tool. I know I need to know the amps a motor takes when it starts. The motor's plate states the full load amperage but not the starting amps. Or does it?

I did a bit of research and I hope I get this correct:
( Information gathered from http://waterheatertimer.org/calculate-inrush-for-3-phase-motor.html )
An induction motor's highest draw is when it's power is initialized and it's armature is not turning. It's "temporarily" shorted! The maximum amperage is now going through the winding. The whole circuit from the power source, through the motor winding and back to the power source instantly starts to heat up. The circuit WILL open. A wire will get red hot and break (hopefully not starting a fire in the process), the motor brushes will burn, the motor winding will heat up melting the coating which creates a more direct short which damages the motor, the circuit breaker trips breaking the circuit or most hopefully, the motor turns enough to open the current and thus close the circuit again with the next winding in the series to start the process again. As the motor speeds to full speed, the amp consumed becomes less and less until it reaches it's maximum no-load speed.

There is a code for a motor's maximum healthy "inrush" current when the motor is first initiated and before the armature begins to turn. The "locked rotor code" is the amperage for that motor to start. The code for my 3 HP motor on my planer is in the lower left "K":



These codes and their meaning is as follows:



So, for my planer, I use the "K" designation, use an amperage just less than the maximum amps in the chart ( 9.0 - 0.1 = 8.9 ) and multiply that number by the number of horsepower to find the thickness planer's inrush. 8.9 x 3.0 = 26.7 A. My MEP-802A will handle that startup, right? Even with a smaller vacuum system operating at the same time?

 

[glcaines]

One question I didn't see an answer for concerns whether or not being off-grid is a permanent thing or do you intend to go on-grid at some point in the future. This question should impact your decisions.

I am not off-grid, but I have an MEP003A that is trailer mounted. I have the single phase cabled underground to my house where it is connected to a 400 amp manual transfer switch for backup purposes. It is large enough to power my entire house, including a geothermal heat pump, ovens, dryers, etc. It gets used 2 - 3 times per month because I am in a very remote area and we have fairly frequent power outages. I also have a shop that has quite a lot of 3-phase woodworking tools with 5 hp motors, such as Delta Unisaw, 14-inch Delta radial arm saw, 20- inch Delta band saw, large Delta Jointer, planer, etc. I have another cable that I use to run 3 phase power to my shop. The MEP003A is a 10KW genset, and it has never had any issues starting anything, including a 5 HP single phase compressor. I have now installed a rotary phase converter so I now have 3 phase power in my shop from the local EMC and don't have to fool with the generator except as backup or remote use. I've had the MEP003A for quite a few years now and it has been virtually trouble free. It's an air cooled diesel so I don't have to be concerned with liquid cooling. Under heavy load I burn about one gallon per hour and a little less under lighter loads. I also like the fact that it is trailer mounted because I move it quite often to other temporary locations on my 40 acres.

 

[Coug]

So the math you posted adds up, it should be in the 24-27 amp range for current.

Just remember that when the genset is turned to 3 phase it has a max rated load of 16.6 amps, not the 26 that it's rated for at 240V single phase.

That means the generator is NOT sized large enough according to the data plates, but that doesn't mean it might not be able to start it up. The data plate ratings are for continuous operation, start surge is momentary, and it wouldn't surprise me if it could handle that much for the very short time it's applied.
(I checked the manual and couldn't find anywhere that gave a motor start surge rating like you see on civilian generators)

 

[smokem joe]

While it may start the 3HP, and that isn't even a for sure thing since you plan on running 1HP dust collection at the same time, it won't start the 5HP motor. Sounds like you should be looking for 803a or larger to power all buildings at once. I'd be very surprised if you could start 5HP with an 802a.

Several of us here refurbish 803A gen sets if you need one. With a 10kw or larger you will just have to be aware of wet stacking and load heavy enough at times to keep it burned out.

 

[Light in the Dark]

Yeah, 803 or bigger is where you will be. Just comes down to if you want to have a machine thats selectable phase, or if you will be able to tap legs for single phase as needed, without unevenly loading certain legs. If you can get away with running a machine at a time, versus multiple machines at once... I think you might do well with the 10kw class.

 

[Guyfang]

Yeah, 803 or bigger is where you will be. Just comes down to if you want to have a machine thats selectable phase, or if you will be able to tap legs for single phase as needed, without unevenly loading certain legs. If you can get away with running a machine at a time, versus multiple machines at once... I think you might do well with the 10kw class.

Or, go back and think about post# 9.

 

[sl33k3r]

Thank you for your replies. Our situation here is a permanent one. We do not want to be grid-connected. Our photovoltaics, solar water heaters, wind power and generators all need to be properly sized for us and our needs. If not, they may be too cost prohibitive for us to change once we are completely retired.

The more I figure things, the more I know I need a larger generator for the workshop. But that's a good thing! I most likely won't be situated with tools and no way to operate them. Now I know this, which one?

I bought this 802 not realizing we would be building a large workshop or understanding the demands of electric motor startup. I don't want to be under-powered in the future as we add equipment. What really surprises me is how big the difference is the three phase amperage output. Its really wonderful how much we don't know. We keep learning and expanding our understanding. Not sitting still like a lump on a log.

Quickly thinking, I would say to just run single phase equipment, but that thought gets squashed when I think of the larger picture. I work with hardwoods and sometimes larger stock. I want equipment large enough to not worry about being strong enough to cut it. The equipment cost savings is something I am believing will work in my favor. I can obtain, larger, stronger equipment for the same or less cost than single phase equipment. Even if I have to spend more on a larger generator, if I spend the same or even slightly more as a total investment in the future, i think it will be worth it to me. I love doing my own work and being able to help my neighbors as they have been good to me.

I have time. I don't believe I am building a workshop for another year and half. I will keep my eyes peeled for a good bargain with more power output. I don't want to have to be concerned what order I turn the tools on in order to be sure they don't overwhelm the generator or damage the winding.

 

[glcaines]

You are absolutely correct in that you can find some fantastic deals on high quality 3 phase power tools at auction. I have almost quit looking for single phase equipment for this reason. The vast majority of home owners don't have access to 3 phase power unless they install a converter.

 

[Hard Head]

Got to agree with this info. And its gotten so bad with copper prices, that the copper usage in the PF, (Photoelectric world) has gone to about 0% here in Germany. Aluminum, that's about all that's used now a days. We used to make fun of the East Germans for using mostly Aluminum, but the jokes on us. It takes a while to get used to be good at hooking up Aluminum cables, (I am not talking about small wires) but once you get the hang of it, I like it better. You have just never lived until you have run 300-400 meters of 240 mm (600 MCM) through a building and then hooked it up! Go to the gym for a work out? Not even close!

I am stripping what is left of my 500mcm and 1000mcm cable to save for when copper goes up in price. I used 300 feet to connect a 400kva gen set to the distillery next door. Used my pickup to pull the cable thru the conduit! It was fun laying out the cable by myself to get ready for the pull. I know your pain and frustration with big cables. I use 250 and 350 mcm welding cable for battery jumpers and it is so nice and flexible compared to building cable!

 

[dav5]

You are absolutely correct in that you can find some fantastic deals on high quality 3 phase power tools at auction. I have almost quit looking for single phase equipment for this reason. The vast majority of home owners don't have access to 3 phase power unless they install a converter.

I buy only 3 phase equipment and power them with an American Rotary phase converter. I convert to single phse only if the 3 phase motor fails. The phase converter has to be a fair bit larger than the motor it supplies though.