MEP 003a

[RAVC1]

I've recently learned of the 'MEP' series of generators and some of these appear quite attractive for power generation for my home. The MEP 003A is the set I've most recently researched and mush of its specifications seem surprising in that a 10 - 14 kW generator is producing inn excess of 100A of current at full load when this corresponds to 120V/60 Hz electricity.

How do they do this? This level of current seems to be available in gensets on the order of 30 kW or greater.

Rick

[Jim Rankin]

Power in kW =Volts x amps x power factor, so 10kw = 10,000 w=120 v x amps x 0.8

10000/(120 x 0.8) = 104 amps on ONE line

at 240V, 104 amps per line on (2 lines) at 0.8 power factor delivers almost 20kW single phase

3 phase 240V 104 ampsper line (3 lines) @ 0.8pf =34.5kW

So you see how the voltage and phasing vs amperage makes a big difference.

[allyoop]

Originally Posted by Jim Rankin

Power in kW =Volts x amps x power factor, so 10kw = 10,000 w=120 v x amps x 0.8

10000/(120 x 0.8) = 104 amps on ONE line

at 240V, 104 amps per line on (2 lines) at 0.8 power factor delivers almost 20kW single phase

3 phase 240V 104 ampsper line (3 lines) @ 0.8pf =34.5kW

So you see how the voltage and phasing vs amperage makes a big difference.

Jim, I understand a little about the conversions, but don't know where you get the "power factor" from. Enlighten me please.

[Jim Rankin]

In the example I posted, I pulled 0.8 pf out of the air. (It's also commonly used when building generator sets) for some reason.

Look at this generator FAQ (reply #8 in this thread)
http://www.smokstak.com/forum/showthread.php?t=47155

Ask away if that doesn't make sense.

[Raymond]

The way they do this is to use 50% oversize winding wire in the stator. This allows them to get full capacity at 120-240V. Just look at the leads and you will see right away they are huge. I have a 15 KW mil. gen SF-15 MD that is rated at 15 KW 120 single phase thats 156 amps, or 78 amps at 240v. The leads are over 3/8 inch in diameter. A standard 15 KW @ .8 produces 52 amps connected "Y" which requires a coil capacity of 52 amps. This would only produce 12.5 KVA at 120V or 240v single phase (connected delta). But if you use 50% oversize windings producing 78 amps, you get the full engine capacity of 15 KW single phase. It costs a little more but negates the need for another machine built for 120x240 only which is common for systems with only lights and small 120 or 240v loads. The bottom line is that with this machine, the generator is stronger than the engine so generator overload will not occur. The engine will slow down and the voltage will droop and the loads will suffer the consequences (theoretically). But since the engine is actually capable of over 30 KW. (the military uses a conservative continuous duty rating) the unit is really capable of over 22 KW maximum. The Mep 003 will easily do 15 KW in "Standby" use. The engine is a DJF which is 140 CU. IN. that will develop 35 HP producing 23 KW Generator output. The mep 003 is the perfect home generator except for it is noisy and the parts are not Onan standard except for most of the engine mechanical, and the electrical doesn't resemble the Onan at all. But there are so many of them I can't believe parts are that hard to come by. They may be used, but used military stuff is far superior to new civilian stuff.