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mep 006a 3 phase to single phase switch

hamrepairguy

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Has anyone thought about using a 3pdt relay and a couple large contactors,To make switching from single to three phase possible by just flipping a switch.

It can easily be done with relays and contactors with 24 volt coils.The only problem is what if one of the contacts develops a poor connection or if the coil were to fail and the contacts were to open.

I would use a key operated switch to switch between the two phases.

Any feedback would be greatly appreciated.
 

Isaac-1

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I suspect it could be done, but I don't see that there is likely that much demand given we are talking about a 60+KW diesel generator here. Also it is not as simple as just 1 / 3 phase operation, since there are several potentially desired 3 phase voltages that would each need different connections.

Ike
 

hamrepairguy

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guilford ct
conversion

Thanks for the reply, From what I understand the mep 004 and 005 use the same reconnection board, voltage regulator and thermal watt converter. So if I do this mod to my generator then the same could be done to the two smaller generators.

You would think that the mep 006a is kinda big, but when converted to single phase the rating is only 40kw or am I mistaken. I live in a house which has electric everything well, clothes dryer , hot water , heat, stove , ac etc etc.I can have a 30kw plus load on the main panel for extended periods of time. And that's not factoring in the inrush from certain things like the well, the ac and the dryer when they first turn on.

I figured that a relay would make the connections under the reconnection board easier to swap back and fourth between 3 and single phase . Which x8hh16b , x8a16b and x12eg16n.

And to use contactors for breaking the connection between 11 and 12 for single phase operation. And reconnection of 11 and 12 for 3 phase operation. And connecting 12 to 8 for single phase operation and breaking for 3 phase operation. Not the best explanation but im sure you can follow.

And for setting the 3 phase voltage option I could just re configure the connections on top of the re connection board.

I don't believe in running something to its max rating. I like having some headroom. So the mep 005 would not have cut it for me.
 
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Suprman

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Here is how a guy converted an 004 to single phase. Full power output in single phase but not easy to go back and forth between 3 phase.
 

Isaac-1

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Ok, a couple of issues, anyone that says the MEP-006a is rated at 40KW single phase is making a guess, it may be an educated guess, but it is a guess since these generators were rated 3 phase only at 60KW, and that rating was likely somewhat conservative, as commercial generators powered by the same engine tend to be rated around 75KW. The unknown factor here is in the generator end and at what point it starts being overloaded, and over heating. The next point of concern here is wet stacking, if you don't know about wet stacking look it up, but simply put diesel engines clog up with partly burnt fuel if ran for long periods of time at light load, and should generally operate a substantial percentage of the time at 50% load minimum, and 80+% ideally. So as you might see we are running into a corner case problem here with an engine that can turn a 75KW generator end running at an effective just over 50% load when maxed out at 40KW single phase output. This is in effect an over sized diesel engine on a generator which is a recipe for wet stacking. Next I would like to ask how confident you are in knowing you need 30+KW, and is this worst case or sustained load? I ask because I have a 33KW commercial diesel generator installed at my elderly mother's house, which is a large (3500+ sq ft heated) all electric house with water well, 3 50 gallon water heaters and 1 20 gallon, 3 resistive central electric heaters, etc. and it can allow nearly normal life with only minimal power management concerns (don't have all the heat on in the house, while cooking thanksgiving dinner, and doing laundry). For winter outages it is limited to 2 of the 3 heaters, plus anything else at once, or will run all 3 if water heaters, stove, etc. are off.

Ike
 

hamrepairguy

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guilford ct
Thanks for all of the Reponses. Ok yes I know for a fact that I have a 30kw load on the main panel for extended periods of time. I have a fluke clamp on current meter which tells me exactly what I have on each 120 volt leg. As for wet stacking I know exactly what it is and have the optional matching load for the generator which I can put in line when I need to.

Im sorry but I didn't start this topic to debate whether the generator is the appropriate size for my application. I was just looking for feedback as to the single to 3 phase conversion idea.

I should add that this generator will not be used primarily for powering my home. I have customers who I intend to rent it to who have the need for 50 kw plus 3 phase.

Can we get back to the original topic
 

jbk

Member
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livingston la.
if i was going to do it i would use a manual rotary switch to reconnect. no problem with the contact failure. good luck
 
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Isaac-1

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Sure, it is just when we get new people around here asking questions like this we have no way to know how much they know about what they are asking, or even if they are asking an appropriate question. As back to the original topic, which 3 phase voltage are they wanting?

Ike
 

hamrepairguy

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guilford ct
I understand, im sorry if I came off the wrong way. I would need 120/208 which I believe is wye or star low volt configuration. I already know how to convert it from either 120/208 or 240/416. I would be going back and fourth from single to 3 phase often. So a mod like I first mentioned would save me a lot of time and also wear and tear on the wires and fasteners.
 
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glassk

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Hampton, GA
I understand, im sorry if I came off the wrong way. I would need 120/208 which I believe is wye or star low volt configuration. I already know how to convert it from either 120/208 or 240/416. I would be going back and fourth from single to 3 phase often. So a mod like I first mentioned would save me a lot of time and also wear and tear on the wires and fasteners.

Sounds like you are wanting to do the same thing as a wye start delta run set up like in 3 phase motors, they have contactors with the interlocks and overloads built in them, see if this wiring looks close to the reconnection board, from delta wye start.jpg


I know that is for a 12 lead motor and if it ain't in the ball park , my bad,...
 

Isaac-1

Well-known member
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Location
SW, Louisiana
My big concern here would be the potential for contactor chatter such as while cranking (I am of course assuming a DC contactor since it would need to operate when the engine was off), there are also the various safeties you need to make sure the contactor would NEVER switch while the generator is running. Overall a mechanical switch or connection board looks very simple and safe by comparison.

Ike
 

Munchies

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The low voltage sensing wires would not be too hard, but the load wiring will be tricky to find a way to switch it back and forth. Only decent way I see is a BIG version of a 002/003a rotary switch and sit down with some catalogs and see if they make one that goes up to the needed amp rating
 

glassk

Active member
998
6
38
Location
Hampton, GA
My big concern here would be the potential for contactor chatter such as while cranking (I am of course assuming a DC contactor since it would need to operate when the engine was off), there are also the various safeties you need to make sure the contactor would NEVER switch while the generator is running. Overall a mechanical switch or connection board looks very simple and safe by comparison.

Ike
, i just thought an off the shelf would be a motor starter, i would just upgrade the lugs on the terminal board and use my cordless impact , that way it's my generator and I would know it went to the site correctly wired, make up an extra board in each configuration,...seems like the money spent on it would take many change overs to make it worth the ten minutes it would save,... although an ac drive would let him run three phase all the time and deliver 3 or single phase with an input to it,


AC adjustable speed drive with unique single or three phase output!
 
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