240V 3ph on MEP-806B. Is it safe?

mlhorton1

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Hi,

I recently purchased a Mep-806B. I have been reading all of the TMs and according to those it safe that for 120v/208v 3ph the voltage range is 197v-240v. I am trying to figure out if turning the voltage of to 240v is safe and if it can sustain that and run for extended periods of time?

Thank you in advance.

Matt
 

rickf

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If you are thinking that you can hook this too your house directly then you cannot unless your house is wired for 3 phase which is highly unlikely. I am not an electrician but I know you cannot connect three phase to single phase.
 

DieselAddict

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The question about safety is more to the loads you plan on running and less about the generator. To run the generator at 240v phase to phase your phase to neutral voltage will be over 135v. I certainly don't recommend doing that.

What are you planning to do with this generator? If its to connect it to a house or other split phase setup I would say NO, it is NOT OK to run the generator that high above spec.
 

Scoobyshep

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You can get 240. BUT the leg to ground voltage will increase as well. Leg to ground is typically 120.

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G744

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Most 240V loads will do OK on 208V. Certain motors will draw more current at that voltage.

I have been running HVAC units designed for 230V on 208V for years with no problems.

Just take two legs & neutral off the genset, and be happy with about 75% of rated output.

DDG
 

mlhorton1

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Sorry I was not specific enough earlier. I am running seed treater with electric motors and then an electric panel. Everything came prewired for 240V 3ph so I need to run at that specific voltage. The FLA for from them is 65 amps so the generator has more than enough power I am just making sure you guys don't know of any problems.

Thanks for all the responses.
 

Scoobyshep

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Sorry I was not specific enough earlier. I am running seed treater with electric motors and then an electric panel. Everything came prewired for 240V 3ph so I need to run at that specific voltage. The FLA for from them is 65 amps so the generator has more than enough power I am just making sure you guys don't know of any problems.

Thanks for all the responses.
Okay this changes things slightly, you need to look at your equipment and see if there is anything that runs 120 volt. If there isn't anything requiring 120 then you can Crank It Up. Also look at the motors and see if they have anything on the nameplate saying usable at 208.

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mlhorton1

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The panel that I will be bringing the power into is wired for 240V 3ph and it contains some computers and stuff so I think I need to go off the requirement of 240v 3 ph. I looked at the motors and they all say a straight 220V 3ph.

My assumption is that it should work fine but figured I would ask people with more experience using this generator.

Also I was wondering if there was anyway to change the starting voltage when I start up the generator.

It currently goes to 210V on startup then I have to turn up the voltage to 240V, but I was hoping there was a way to change the startup voltage to 240V I have not found anything in the TMs.
 

98G

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The panel that I will be bringing the power into is wired for 240V 3ph and it contains some computers and stuff so I think I need to go off the requirement of 240v 3 ph. I looked at the motors and they all say a straight 220V 3ph.

My assumption is that it should work fine but figured I would ask people with more experience using this generator.

Also I was wondering if there was anyway to change the starting voltage when I start up the generator.

It currently goes to 210V on startup then I have to turn up the voltage to 240V, but I was hoping there was a way to change the startup voltage to 240V I have not found anything in the TMs.
Your computers and stuff are likely to try to pull just one leg off of it and will be getting 135v instead of the expected 120v.

I'm thinking no go.
 

MrShawn305

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The panel that I will be bringing the power into is wired for 240V 3ph and it contains some computers and stuff so I think I need to go off the requirement of 240v 3 ph. I looked at the motors and they all say a straight 220V 3ph.

My assumption is that it should work fine but figured I would ask people with more experience using this generator.

Also I was wondering if there was anyway to change the starting voltage when I start up the generator.

It currently goes to 210V on startup then I have to turn up the voltage to 240V, but I was hoping there was a way to change the startup voltage to 240V I have not found anything in the TMs.
If you're running computers and such, I would stick to 208. Look at the L-N voltage and bump it up until you get to 120. L-L should be something like 212 at that point. The motors will likely work just fine. If you bump the L-L to 240, your L-N will be around 139 which is too much for the 120 circuits.
 
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mlhorton1

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I feel like there may still be some confusion. The panel is wired up by the company I bought the machine from and I simply need to supply it with 240V 3ph. I doubled checked the inside of the panel and it says to supply 240V 3ph. I am making sure that a MEP-806B should be able to go up to 240V and run for 10 hours or so a day.
 

MrShawn305

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I feel like there may still be some confusion. The panel is wired up by the company I bought the machine from and I simply need to supply it with 240V 3ph. I doubled checked the inside of the panel and it says to supply 240V 3ph. I am making sure that a MEP-806B should be able to go up to 240V and run for 10 hours or so a day.
There is no doubt about whether or not it can. It can absolutely do the job. The point we're trying to make is that the machine is designed to run 120/208. It has a voltage adjustment to give you some working room. But if you set the 208 side to 240, then that brings your 120 side to 139v. Most 240 devices (including your panel) will work with 208. But the same is not true of 120 devices. Those need 110-125 and bad things can happen if you go outside of that range. So most of this is just a warning to you. If you feel the correct thing to do is set it to 240 and run it, then send it. But me personally, I would set it at 212 and give it a try to see how the whole thing works. If it doesn't seem to like it, then bump up the voltage.
 

mlhorton1

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Yes the panel has a neutral bar and then there is a breaker for 240V 3ph with L1 L2 and L3. I have looked through the panel and the only thing that is 120V is a special outlet, by special I mean that it looks a lot more bulky that any other outlet I have wired up, that they have mounted to the side to deliver 120V to an air compressor that is mounted on the trailer. I talked to the company and they have assured me that they have everything set to take in the 138v/240v and convert it to what is needed.

Thank you guys for the help and confidence in the generator.

Does anyone have any idea if changing the starting voltage is possible and/or changing the graph on the display to go up to 260 like is displayed in the TM?
 

Ferroequinologist

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Your 220 motors will be fine at 208. The issue everyone here is pointed out, is that the hot to neutral is 120 when the set is running at 208 3phase. If the panel has computers in it, they are 98% sure going to feed off just one leg of the 3phase to the neutral, so they will see the proper 120v when it is run at 208 3phase. That is the important bit. I have a very expensive mig welder with electronics in it. Where I used it the most for over 10 years had 208 3 phase. ran fine, because the electronics got the proper 120v.

If you crank the voltage up to 240, the leg to neutral will be 135- too high for the electronics more than likely. Just because the panel says 240v, doesn't mean that's what it will get even plugged into commercial power. I have seen '240v 3 phase' be anything from 214v to 254v with a corresponding leg to neutral decrease from 120 to increase from 120. Most motors can take that wide a swing and be just fine. Electronics? not so much.

:Edit: well if you talked to the company, then I would say you were good to go
 

Coug

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The vast majority of equipment and electronics have a little bit of leeway when accepting voltage. Usually if it's within a 10% variance will be fine.

That 220V motor isn't going to care much, if at all, about only getting 210V instead of 220. Just like it doesn't care about getting 240V instead of 220.

The 120 side of things, you can probably get away with up to 130V no problems, as utility voltage that we designate as "120V" can be anywhere from 110-125, or a little outside of that, with no adverse effects.

As for the generator, it's not really going to care as long as it's within the range it's rated for.
 

Scoobyshep

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Does your hook up have a neutral? If it does then something uses 120. Of they are rated at 220 then 208 will be just fine.

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robertsears1

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I would suggest that you hook up the generator without the computer suppy energized if possible. Then get a meter and try to read the voltage in the control box where hopefully the computer part is not plugged into yet and see what you get with different voltages . Is this system totally separate from the building Wiring and the grid? If yes, then make sure you have a good ground for the generator just like you were in the middle of nowhere.

Robert
 
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Scoobyshep

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Remember proper bonding. If its only powered from the generator it is a separately derived system, so the neutral needs to be bonded to ground.

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