MEP-002A and -003A main breaker

wciguy

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Lubbock, Texas
I have "restored" and sold around 30 002a and 003a units and over a dozen 004a, 005a, 006a, 805a and 806a units. Load tested the 002a units at 8KW for an hour and the 003a units at 13KW for an hour. No breaker trips.

The utility class MEP units are rated to start a 3-phase motor of a horsepower 1/3 the KW rating of the genset, i.e. a 30 KW set will reliably start a 10 hp 3-phase motor. The precise class units are rated to start a 3-phase motor of a horsepower 1/2 the KW rating of the genset, i.e. a 30KW set will reliably start a 15 hp 3-phase motor. YMMV.

The difference seems to be the response time of the governors on the engines. The newer tactically quiet sets, i.e. 805a, have electronic governors and handle the larger motors. If trying to start motors larger than these ratings you can expect circuit breakers to trip and count yourself as blessed if they don't.

Gotta say thanks to all you guys for all the great information on the thread.
 

W8BUH

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Location
West Branch , Mi.
I purchase a MEP-003A and having problem starting it. One of the three fuel pumps is working. The transfer pump that you connect to an outside fuel source is working but the main pump was not working. I changed the pump and put in one from the auto parts store. I checked the voltage that is coming to the pump and it has 24volt to it but is not working. I checked the ground. Does all three have to be working to get the unit started. The pump I took off is not working. I hooked up 24 volts to it and it would not work. Hope someone in the group can help me with it.
Thanks
 

wciguy

Member
34
2
8
Location
Lubbock, Texas
I purchase a MEP-003A and having problem starting it. One of the three fuel pumps is working. The transfer pump that you connect to an outside fuel source is working but the main pump was not working. I changed the pump and put in one from the auto parts store. I checked the voltage that is coming to the pump and it has 24volt to it but is not working. I checked the ground. Does all three have to be working to get the unit started. The pump I took off is not working. I hooked up 24 volts to it and it would not work. Hope someone in the group can help me with it.
Thanks
There are 3 fuel pumps. Two are hooked up in series to supply fuel to the injector pump. The third, or "Auxiliary Pump" is strictly to transfer fuel from an external tank to the on board tank so it can be run for an extended period. If one of the other pumps is running and working correctly, it will supply sufficient fuel to the injector pump to run the engine. However at least one of them must run, preferably both.

If you correctly installed a new pump so that it is grounded and it is getting the correct voltage, it should run. Perhaps it is defective.
 

bones1

Member
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18
Location
Southern Maryland
Excellent thread .Read it all. I see reference to people rebuilding and testing 30 units here and 20 units there and then selling them. Would someone be so kind as to tell me where to purchase one?. One that will pass the load test without tripping. I see only one in the classifieds and few on ehay.
Thanks.
 

jamawieb

Well-known member
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Ripley/TN
Excellent thread .Read it all. I see reference to people rebuilding and testing 30 units here and 20 units there and then selling them. Would someone be so kind as to tell me where to purchase one?. One that will pass the load test without tripping. I see only one in the classifieds and few on ehay.
Thanks.
Most of the people, like myself buy in bulk. When an auction takes place from the various online sites, they usually place a large number of units for sale at one time. When that happens I will buy as many as possible because it reduces freight cost. Then I resale all my units on craigslist or ebay. I don't try to rip people off and sell my units with smaller profit margins but I sell a lot of them. I've sold 30 generators this year alone.
 

Blazer8750

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Location
Cincinnati, OH
Ok, so I read 97% of the posts in this thread. Great thread. I am having a similar issue; starting a 3ph 10hp compressor motor with an 002A. Trips every time.

Has anybody actually by passed the OEM breaker? There was plenty of talk about it.
 

Triple Jim

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10 hp is going to be somewhere around 8 or 9 kW when running. It's hard to imagine a generator rated at 5 kW handling that load, say nothing of starting it.
 

jamawieb

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Location
Ripley/TN
Ok, so I read 97% of the posts in this thread. Great thread. I am having a similar issue; starting a 3ph 10hp compressor motor with an 002A. Trips every time.

Has anybody actually by passed the OEM breaker? There was plenty of talk about it.
Yes, I've actually bypassed the breaker by hooking the main wires together on the back of the breaker. Then I put an ordinary 50 amp house breaker inline of my load. It has worked well thus far but would not recommend this to anyone because I have a lot of experience with these generators and would hate someone to ruin their genset by bypassing safety features.
 

GREENMV

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Linden, TN
Mep-003a Breaker Replacement. Has anyone found a good replacement / aftermarket 100amp breaker that Is a drop in to replace a bad breaker on the 10Kw? Or has a good supplier for a new OEM at reasonable price.
 

GREENMV

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Linden, TN
Famous Auction Site, Type In CD3-Z142-1 If you buy 2 or more, Free Shipping. We will see If I get the 100amp breaker? The TM for the 5Kw TM-9-6115-584-24P Page 53 Item 72 Is part# CD3-Z142-1 and the TM for the 10Kw TM-5-6115-585-24P Page 51 Item 72 Part# CD3-Z142-1 even though the diagram says 73. They are the same part# ?
 

Guyfang

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They are the same part. But did you notice, that there are two circuit breakers listed. According to what Serial number of the gen set has, the UOC, (Usable On Code) list two different NSNs. Big price difference between them One is 74 bucks. The other is 329 bucks. There is listed at least 3 different manufactures.

After reading this whole thread, maybe this is why some folks have a problem with the circuit breaker popping under a sudden "shock load", and some people not? I confess, I have no idea, nor have I ever heard a rumor.
 

GREENMV

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@Guyfang, I did notice the different part #'s for the two, I was assuming the other breaker was for the 400Hz Gen. I have the same problem with my 10Kw Gen, It wont start a 5 HP motor and It should. I read this whole thread also and I don't think anyone came up with an answer to the question, Why some will start heavy amp loads and some wont. I did try with my Fluke Meter to capture Start amp's, but It Trips to fast for It. I did get that the breaker might be bad and that Is why I ordered some. I still don't know why the 5Kw TM and the 10Kw TM has the same part # for the Main Breaker. One Is 50 amp and the other Is 100 amp. will see what I get when they come In. I hope someone reading this Post might be able to update us or answer why the breakers are tripping not under full Load and If anyone solved this problem. Different Part #'s or breakers? I do have a question, Is It ok to use the 5Kw AC box on a 10Kw Gen buy just swapping out the 50 amp breaker with a 100 amp breaker. I did read someone was doing this.
 

Guyfang

Well-known member
7,521
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113
Location
Burgkunstadt, Germany
@Guyfang, I did notice the different part #'s for the two, I was assuming the other breaker was for the 400Hz Gen. I have the same problem with my 10Kw Gen, It wont start a 5 HP motor and It should. I read this whole thread also and I don't think anyone came up with an answer to the question, Why some will start heavy amp loads and some wont. I did try with my Fluke Meter to capture Start amp's, but It Trips to fast for It. I did get that the breaker might be bad and that Is why I ordered some. I still don't know why the 5Kw TM and the 10Kw TM has the same part # for the Main Breaker. One Is 50 amp and the other Is 100 amp. will see what I get when they come In. I hope someone reading this Post might be able to update us or answer why the breakers are tripping not under full Load and If anyone solved this problem. Different Part #'s or breakers? I do have a question, Is It ok to use the 5Kw AC box on a 10Kw Gen buy just swapping out the 50 amp breaker with a 100 amp breaker. I did read someone was doing this.
I posted in the other thread some more info. The military uses the same CB, in both sets, because its simply cheaper to stock one kind of CB. There is no 50 Amp CB. So you don't have to change anything other than the way the CT's are wired, just like Jamaweib, (I think?) wrote. But I would be interested in what part number is on the CB that pops too early. There has to be a difference between the two CB's. One cost 75 bucks, one cost 330 bucks. Something has to be different. And a CB works how? If I remember right, heat, (thermal contacts?). When you have an overload, it produces heat, and that pops the circuit breaker. Well, if its 400 or 60 hertz power, the heat caused by an overload should not be any different. Or should it?
 

Triple Jim

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I believe the breaker that's desirable is one that if basically a magnetic type, by also has a fluid damped mechanism. At slight overloads, it acts like a slo-blow fuse, allowing the overload to go on for quite a while before the damper lets it trip. With more severe overloads, it trips faster, and if the overload is big enough, the magnetic force overcomes the damper, and it trips immediately. After reading about this type, I got the impression that if the fluid damping mechanism got old and leaky and quit working, you'd be left with a breaker that trips quickly on any overload.

I don't know which breaker(s) are this type, maybe only the expensive one, maybe all of them.
 
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