Generator Sizing Assistance Please

[oldMan99]

I am looking at a piece of equipment and need to know what size generator I need to run it. I'm good to go on sizing for single phase but I have never messed with 3 phase stuff so now I'm lost. Any help much appreciated.

The data plate says:

208/230 vac, 3 phase, 50/60 hz, 60 amps per phase.


What size genset do I need to run this thing?

What would be the mil designation for this size unit?

What would be the mil designation of a genset to run 2 of these units at the same time?

Would I also be able to pull 110/220vac SINGLE PHASE off the same genset at the same time?

As always; THANKS in advance!

 

[Speddmon]

I am looking at a piece of equipment and need to know what size generator I need to run it. I'm good to go on sizing for single phase but I have never messed with 3 phase stuff so now I'm lost. Any help much appreciated.

The data plate says:

208/230 vac, 3 phase, 50/60 hz, 60 amps per phase.


What size genset do I need to run this thing?

What would be the mil designation for this size unit?

What would be the mil designation of a genset to run 2 of these units at the same time?

Would I also be able to pull 110/220vac SINGLE PHASE off the same genset at the same time?

As always; THANKS in advance!

To run 2 of the machines you provided the name plate data for at the same time, you would need an MEP-006a 60 KW generator. If you were only to run one at a time, then you could get by with an MEP-005a 30 KW set.

Keep in mind that the data you provided is for "Full Load". If you knew for a fact that the machines would not be running at full load, then you could probably get by with an MEP-005a for both machines. The MEP-05a has a current rating of 104 amps at 120/208 volts 3 phase and 52 amps at 240/416 volts 3 phase. Also, using the statement about not running at full load, if you were to run one machine at a time, you could probably get by with an MEP-004a 15 KW set for just one machine.

Also, unless the motors and controls on the equipment you are planning on running is dedicated for 208/240 volt 3 phase only, I would rewire the motors and control transformers to use the available higher 240/416 volts 3 phase. The current requirements would be lower so you could use smaller wires and make it easier to rig up a transformer for the second part of your question...below.

Would I also be able to pull 110/220vac SINGLE PHASE off the same genset at the same time?

Short answer, no, not in their current configuration. The MEP series generators about 10 KW are 3 phase only. To get 120/240 single phase while running 3 phase equipment, you could rig up a transformer and make your own single phase power though.

 

[PeterD]

You could pull some 120/208 off to get single phase if you needed, but if you are fully loading with the equipment you are describing then you may not get a lot of spare power from a 004. A MEP-004 is rated at about 52 amps per phase, so at maximum load you'd be slightly over the book rating. But a 004 is tough, and can handle an overload normally. To run two of these units, then a MEP-005 would be needed, or better a MEP-006 which would give some additional power for other circuits.

 

[Isaac-1]

It would help to know more about the type of equipment this is. Right now we know it needs 60 amps per phase when running at full load, but there are a lot of other factors to consider. For example if this has one large electrical motor that starts under load like for a compressor it will have a much higher inrush starting load than if it were something with several smaller motors that don't all start at once. If it uses a contactor and a large motor then the voltage drop from the large motor starting it could cause the contactor to drop out and chatter whenever the motor tires to start. Or alternatively if the device is something like a large SCR based battery charger the reactive load of the SCR's can cause excessive heating in the generator coils requiring a larger generator than would be suggested by the amp draw alone.

Ike