which generator mep002 or mep003

[rat4spd]

forget kw compare amps

I'll stick with kw since it is a unit of power.

 

[Speddmon]

Speddmon, this may be getting a bit off topic, but Onan did make a 3.5 inch bore J series diesel engine in their civilian models, the 17.5RDJF, the big difference between this and the MEP-003a engine is the RDJF is a water cooled block.

Ike

Ike,

It's not off topic at all, I just reaffirms what I was saying that the 3.35" bore 12.5 KW would have less HP than a 3.5" bore motor...obviously, the 3.5" civi model can handle 17.5 KW in Onan's eyes.

And back to the point about the military under-rating the motors, their version of the 3.5" bore motor is only turning a 10 KW head....see what I mean.

 

[Bill W]

I think what may be confusing here is the output rating that the military puts on these units.,As I understand it, these units don't put out 80% of what they're rated for!, the mil has them only rated for 80% of what they really can put out, this way they'll have a 100% duty cycle running AT they're full (military) rated KW, ( i.e. mil rated 10kw can run 24/7 at its mil rated 10kw load ), it will handle larger ( surge) loads but constant higher loads will affect the duty cycle

 

[rat4spd]

That is a valid point, however, one interesting note is that it is rated for 100% output and duty in a single phase configuration. Normally on a three phase set of windings, the output would be have to be de-rated in single phase. This is probably the largest clue that the generating head is vastly under-rated, aside from the very large wire it has coming out of it.

 

[atankersdad]

Great thread on generators. Very analytical with lots of data. I had never thought about the BTU's going in as a fuel source. I have several of the 003a's. I love mine. The civilian gen units cannot touch what I have for the price. Thanks guys for taking the time to lay this out.

 

[Isaac-1]

There are other differences in the military ratings vs. civilian ratings:

Civ sets tend to be rated at 80 degrees F must be derated over this

Military tend to be rated at 100 - 120 degrees F

Civ sets must be derated if operated over 1,000 (NA) - 5,000 ft (turbo) altitude

Military at least my 016b rated as output at 8,000 ft.

Ike

 

[Csm Davis]

The military took into account the .80 (80%) power factor rating, that's why the set is rated for 10KW at 80% PF. The TM states "A 0.8 power factor load equals a 100% meter reading for maximum rated load. A 1.0 power factor load equals a 80% meter reading for maximum rated load"

Speddmon I would like you to try spell this out for me please I will tell anyone I don't know it all but I don't get it

 

[Csm Davis]

I'll stick with kw since it is a unit of power.

I am talking about when comparing the military gen sets to the civilian ones they don't lie as bad about the amps that a civilian one can handle as they do kw. Also most homes use 220 so if you know what your house max amp draw is you can match that to the gen set you need without having to figure watts.
amps x volts= watts

 

[rat4spd]

I am talking about when comparing the military gen sets to the civilian ones they don't lie as bad about the amps that a civilian one can handle as they do kw. Also most homes use 220 so if you know what your house max amp draw is you can match that to the gen set you need without having to figure watts.
amps x volts= watts

Sorry, I just can't make myself do it......I may need to be tied down and restrained.....maybe a little elctro-shock therapy..

Maybe Speddmon can help me, but I think I'm hopeless.

 

[Speddmon]

Speddmon I would like you to try spell this out for me please I will tell anyone I don't know it all but I don't get it

When you said that the military sets were rated for 0.8 and not max like the civilian ones...In actuality, they are both rated at the maximum.

The 0.8 you were referring to is for power factor. Simply put, the only way to achieve a pure power factor of 1.0 is with a purely resistive load. Any kind of motor, no matter how small messes with the sine-wave and thereby creates a negative power factor. Larger industries with many motor oriented loads use synchronous motors or capacitor banks to bring the sine-wave back into near perfect conditions...they call this power factor correction, and large users such as industry actually get surcharged if they do not correct the power factor. Now, you and I, as home users are never going to go the the expense of correcting power factor, and just the same, we do not use enough electricity to need to worry about it either.

The military does though, and this is why the put the rating on their generators. Basically what they are telling you is, if you are running motor loads with your MEP-003a, then you are safe to load the generator to the maximum 10 KW load, and you'll be fine. However, if you are using the generator to supply a load that has a perfect power factor, then your maximum 10 KW load will only be registering 80% load on the gauge. Forgive me for not getting more technical with this part of the explanation, but when you figure KW, you actually need to take into account the power factor of your load as well....but it's been almost 15 years since I have had to delve this deep into electrical theory, and I would need to re-educate myself to get it right. But for all intents and purposes, KW is figured simply as (Volts x Amps x power factor) /1000.

So, that being said your 10 KW MEP-003a will figure to be (52 amps x 240 volts x 0.8 power factor) / 1000 = 9.984 KW. Your civilian generators should be calculated the same way, but for the average person they usually do not mention the power factor.

I am talking about when comparing the military gen sets to the civilian ones they don't lie as bad about the amps that a civilian one can handle as they do kw. Also most homes use 220 so if you know what your house max amp draw is you can match that to the gen set you need without having to figure watts.
amps x volts= watts

Sorry, I just can't make myself do it......I may need to be tied down and restrained.....maybe a little elctro-shock therapy..

Maybe Speddmon can help me, but I think I'm hopeless.

I'm not into the civilian generators as much as I am the military ones, so if there is a discrepancy in the amp ratings of the two, it would be because of the power factor correction as I stated above. It's quite possible that if you had a 10 KW civilian set the amp rating should be lower than the military set, because they would not take into account the power factor...example; a 10 KW civilian might look like this...(41.66 amps x 240 volts) / 1000 = 10KW.

Notice that the civilian example does not take into account the power factor rating, thereby you only have a amp rating of 41.66 amps, versus the military rating of 52 amps for the same 10 KW name plate.

This example could be totally off, but like I said, I'm not as up to speed on the civi sets.

 

[Speddmon]

I just pulled this image out of a Briggs 10 KW generator manual I found on the internet...it shows the 50 amp receptacle on the generator, but below the picture it tells you that you should only connect a load that requires 41.6 amps.

So that example shows that the civilian sets are NOT calculating the power factor like the military ones and are not rated for as much current draw either.

 

[Carl_in_NH]

I have to wonder about the ratings on inexpensive 'big-box' civilian gensets; from what I've personally seen they seem to run one or two cylinder engines that are rated about 20% more HP than the rated output rating would dictate at 746W/HP. That's not a lot of surplus power to account for the losses in the overall system. I'm somewhat doubtful of those HP ratings on the engines, too; sure, it might put out that HP, but for how long? One turn of the crank, or 24/7? Likely a turn or two.

You've also got to question what the Trise is at rated output for the generator head itself; there's just not that much copper or aluminum in there, given cost considerations.

That's probably why these generators will get you though an emergency or two, and then begin the decent into failure. There's just no margin in the design - because design margin costs money, weight, and reduces fuel economy.

I tend to think the inexpensive 'big-box' civilian generators are rated like shop vacs; optimistic at best, a downright deception at worst.

 

[rat4spd]

Speddmon, dangit for you for bringing up power factor. There are three types of power, in the power triangle. Apparent power....the power you see on your meter, real power....the actual power put out by the generator which can be measured by fuel use....it's the energy in vs. energy out, and you have reactive power, or as we in the biz call it, VARS.....this is the power used by a piece of machinery taking into account how the expansion and collapsing of magnetic fields in windings tend to try to prevent the flow of current in things like motors. It means it takes more energy than 746w to turn a 1hp motor, and that translates into more hp input by your prime mover.

What all this really means is a Pandoras box for anyone that wants to learn it, but really, it mean it takes more than 1hp to make 746w. Clear as mud right?

 

[Speddmon]

Sorry, I was just trying to clear up the differences in why the sets are rated why they are...honest! But the power triangle is why I didn't get out the old books and start reading about it again for the post...I was going by memory. I didn't like it the first time around when I had to learn it, and I sure don't want to have to go through it again.

I'm more of a hands on kind of guy, the theory stuff is interesting, but I like to get dirty and see sparks!!!

Anybody who want's to debate apparent vs real power, power factor correction and why it's important and all of that good stuff, I'll send them your way ...or they can take a couple of years of correspondence classes and learn it the "fun"way

 

[rat4spd]

Sorry, I was just trying to clear up the differences in why the sets are rated why they are...honest! But the power triangle is why I didn't get out the old books and start reading about it again for the post...I was going by memory. I didn't like it the first time around when I had to learn it, and I sure don't want to have to go through it again.

I'm more of a hands on kind of guy, the theory stuff is interesting, but I like to get dirty and see sparks!!!

Anybody who want's to debate apparent vs real power, power factor correction and why it's important and all of that good stuff, I'll send them your way ...or they can take a couple of years of correspondence classes and learn it the "fun"way

I don't want to debate PF with anyone. It's an absract concept which got me banished from the control room numerous times on shift......We would spend 8 hours talking about it, because it gets even more complicated in a co-generation system.

As an example, our generator is rated at 0.55 PF. This doesn't change the KW output of the set, it only decreases the amp ouput at an equivalent KW (MW) load as PF increases, adn I can change PF on the generator at will to show this.

 

[screejunk]

I realize this is an old thread, but I just did a blog post regarding noise levels for the MEP-002A and MEP-003A units. The bottom line is that they are about the same noise level as Honda's best and largest worksite generator. This is without the ASK. The O02A is 2 dbA louder than the 003A. Tuning your unit and ensuring it is tuned properly with the injection pump is key. Ensuring there are no loose parts on the unit is also key...One little rattle can drive you crazy... So military units are not any louder than similar gas units -- even good ones. I completely disagree about store-bought sound attenuation features. They are very expensive and much higher than a $200-300 feature. Building a simple plywood cabin around your MEP is easy and cheap and does a great deal to deaden the sound and direct it away from your home/building. Just ensure proper and generous cross-ventilation in the units as they are air cooled...Here is my post on how loud MEP-002A and MEP-003A units are compared to lots of other noises and Generac and Hondas... My bottom line is that the noise levels of military units is the SAME as civilian units and is waaay over blown....

 

[edgephoto]

I realize this is an old thread, but I just did a blog post regarding noise levels for the MEP-002A and MEP-003A units. The bottom line is that they are about the same noise level as Honda's best and largest worksite generator. This is without the ASK. The O02A is 2 dbA louder than the 003A. Tuning your unit and ensuring it is tuned properly with the injection pump is key. Ensuring there are no loose parts on the unit is also key...One little rattle can drive you crazy... So military units are not any louder than similar gas units -- even good ones. I completely disagree about store-bought sound attenuation features. They are very expensive and much higher than a $200-300 feature. Building a simple plywood cabin around your MEP is easy and cheap and does a great deal to deaden the sound and direct it away from your home/building. Just ensure proper and generous cross-ventilation in the units as they are air cooled...Here is my post on how loud MEP-002A and MEP-003A units are compared to lots of other noises and Generac and Hondas... My bottom line is that the noise levels of military units is the SAME as civilian units and is waaay over blown....

I have a Generac GP7500E and it is no quieter than the MEP-002a I bought. I was thinking of buying an ASK for my MEP-002a. Have you done a test with an MEP-002a and an ASK?

 

[screejunk]

Anyone have specs for noise level with ASK?

I have a Generac GP7500E and it is no quieter than the MEP-002a I bought. I was thinking of buying an ASK for my MEP-002a. Have you done a test with an MEP-002a and an ASK?

The specs that I made about MEP002A and MEP003A were directly from a military manual, namely: MEP-Various-Handbook-for-Mobile-Electric-Power-Engine-Generator-Standard-Family-General-Characteristics-MIL-HDBK-633/.

They were not my own tests. The ASK was a retrofit to the original MEP002A and MEP003A models and I have yet to find a sound spec for them. Does anyone have one? I do own a MEP002A with an ASK and it does help, but a small simple plywood cabin does a pretty good job too. If you lined the cabin with rockwool, it would be even better! I like the cabin idea a lot as it makes servicing much nicer. It also makes inspecting for mice a lot easier!