MEP-002A and -003A main breaker

Triple Jim

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I exercised my MEP-003A today. While it was powering my house's normal loads, I let enough air out of the tank to make my 5hp compressor start. It's an industrial compressor with a real 240V 5hp 1725 rpm motor that is rated at 24 Amps at full load. It started and ran OK, although you could tell that it started a little slower than when on commercial power. The breaker on the 003A did not trip.

Based on this and the posts earlier in this thread, if the breaker on the generator trips too easily on surges, I'd suspect something is wrong with the fluid-delay type breaker.
 

keen4007

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Former Townie

I have recently purchased a MEP003A that had been setting outside for several years. After new starter and batteries I was able to start it only to find it's not generating. I have spent some time studing the schematic and checking continuity oflot's of wiring and have yet to find any opens or shorts. I am beginning to suspect the gen is the culprit. Is there an easy test for this. Make it easy, 24V is about as high as this 40 yr heavy equipment mech is familiar with.
 

sewerzuk

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I have recently purchased a MEP003A that had been setting outside for several years. After new starter and batteries I was able to start it only to find it's not generating. I have spent some time studing the schematic and checking continuity oflot's of wiring and have yet to find any opens or shorts. I am beginning to suspect the gen is the culprit. Is there an easy test for this. Make it easy, 24V is about as high as this 40 yr heavy equipment mech is familiar with.
Probably best to start a new topic on this...as it doesn't really pertain to the main breaker issue
But the most likely culprit on an -003a is a bad VR board.
 

CNGsaves

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Was it ever resolved if MEP-002a and MEP-003a gensets that Sewerzuk had troubles with air compressors (or other large hard start loads in 240v) had actual breaker problems or required "adjustment" of some kind?

I'd hoping that MEP-002a that I plan to purchase will handle my 3 ton A/C for house if load is managed with slow start by the A/C unit (ie may need to install hard start kit). Any users with MEP-002a successful in running their A/C units? Others having breaker trip problems like Sewezuk?
 

jbk

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i had similar thoughts this year posted a thread. i wanted to start 2 1/2 or 3 ton central unit with the 002. rla was the killer. 17 240 amps to run but the rla was 112 240 no way the 002 would do it. i used a 003 for this ac this hurricane season and it made the meter jump real good. so check your spec. on the ac some of the older units have just 2 times to run surge.
 

jbk

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i think your right jerry. i dont recall the breaker size it was my daughters house. i just know this was the max. surge of the ac, 112 amps 240. 17.6 to run
my old 4 ton unit states 26amps to run and 46 surge.
 

CNGsaves

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Thanks so much to Speddmon, Ike, Sewerzuk, JBK, Storeman, etc. for sharing all your experiences and knowledge. You guys are awesome!

I've spent last 2 days reading EVERY post on MEP-002a and MEP-003a so some of this info swimming around upstairs . . . . it was around 29 pages of 20 posts per page x number of pages in all those posts!

Ran thru calculation that Speddmon provided for my specific 3 ton A/c which is 13.4 RLA and 78 LRA. That equates to 1.73 x 208 x 78 x .8 / 1000 = 22.45 Kw Thus, looks my best bet is trying MEP-003a if I hope to run 3 ton A/C on house with MEP-003a as backup generator. The little MEP-002a just won't cut it.
 

Squirt-Truck

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This is a great thread.

Did anyone ever try the idea to install an alternate main breaker that will still protect the generator and not be as sensitive as the OEM breaker?

This sure seems like a simple fix, if say an 002 is good for 30 amps and a standard 30 amp breaker will start the compressor, why would this not work and provide the required protection??
(Do not laugh, I am a mechanical guy which aspires to the theory that if you cannot fix it with a hammer it has to be an electrical problem.........)
 

3dAngus

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This is a great thread.

Did anyone ever try the idea to install an alternate main breaker that will still protect the generator and not be as sensitive as the OEM breaker?

This sure seems like a simple fix, if say an 002 is good for 30 amps and a standard 30 amp breaker will start the compressor, why would this not work and provide the required protection??
(Do not laugh, I am a mechanical guy which aspires to the theory that if you cannot fix it with a hammer it has to be an electrical problem.........)
If it's going to be a sticky, I would think it would have a solution. I just read six pages and cannot draw any solid conclusions.
Just the fact that my gen set doesn't play well with inductive surges. Is this a misapplication of the intended use. Did the military use these generators for 40 years and not notice?
Is the load faulty? I find it difficult to believe the military did not know these gen sets are not appropriate for industrial motor startups, so what conclusions would we draw from that.
What is the intended purpose? Should be in a tech manual somewhere, or else dozens or hundreds of write ups would be made for improvement or defect and repair.

We're overlooking something a bit more obvious here, but I don't have time to research it.

Not sure why this is a sticky. It could be reduced to one or two posts if made into one to reduce the reading.

I would swap out the circuit breakers for another manufacture and give it a shot. It seems the OEM are over engineered for the tasking.
 
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3dAngus

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Looks like they built the relay for .85 amps and marked it for .75 amps tripping. They evidently found a problem back in 1984, but I doubt that specific issue would relate to the huge surges reported here on industial equipment and household central air conditioning unit surges, where a cheapo Lowes 5 hp might handle the surge as reported in the post above. It just has to be tested on a case by case basis.
If I ever get back on my 5KW and test, I will test it with a good running A/C that has been tested with a bigger genset. I have tested it with a military horizontal heat and air unit rated at 36K BTUs and the heat comes on but fully bogs the 5KW gen set down. The A/C compressor, when in A/C mode does not come up at all, but the fan comes on. These kinds of things cannot draw any conclusions as the A/C is not tested and verified as good, but I did find it interesting the heat would really bog down the generator. I did get good heat and there was no trip, but that heat is strip heat and resistive in nature. I need to test further to draw any conclusions, but I can almost predict accurately this gen set will not run the A/C due to the starting nature of high current on a compressor and inductive loads.

I feel, based on the posts above, and a treasure trove of information, the use of a 5KW or 10KW gen set for an inductive load provided by shop equipment, electrical motors, starting capacitors and compressors, is a misapplication of these types of gen sets. But what remains inconclusive, is what did the military engineers, who put out the spec for manufacture, have in mind, and what did the operators have for guidelines in applications in the field. Surely they were told these gen sets were not functional for industrial motors and they had this as common knowledge, and the primary useages were for low level starting or resistive current applications like lighting for tents and not for motors, where they had to have instructions to bring along a much higher rated gen set, like a 15, 30, or 60kw generator for motor startups.

It's beginning to make the cheapo 5-7.5kw lowes gas generator look more and more promising for all around useage, provided you don't need it for more then a day or two at a time without maintenance, unless you specifically need 3 phase power for non inductive loads. If anyone wants a 5kw on a trailer for sale, reasonably priced and in good condition, check the classifieds. I'll be putting mine up for sale shortly, before I go through all the aggravation of wiring it up and trying to make it work with my home A/C unit. I never planned on using it for a 3 phase power shop. Thanks for all the info guys.
 
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Isaac-1

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How much aggravation is there in replacing the output breaker? Keeping in mind that most commercial generators in this size range have breakers that do little or nothing to protect the generators from overload as the thermal trips are too slow to save them most of the time on slight overload, and many of these generators can not provide enough instantaneous reserve to trip the standard 10X load magnetic instant trip in a common thermal/magnetic breaker.

Ike
 

Munchies

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From airpax
"Hi Joshua,
Here is some information on circuit breaker part number 299-3-4798-1 that was set up for Libby Welding many years ago. I’m sorry for the hard to read information but it was done in pencil at that time.
Please feel free to forward my contact information to whomever.
Regards,
Gene

Gene Duma|Senior Application Engineer|Sensata Technologies|(P) 508-236-5418|(F) 410-228-3456|E-mail: eugene.duma@sensata.com
"

Maybe he can answer specific questions regarding why/when the breaker trips.
 
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