MEP-002A and -003A main breaker

[GREENMV]

Here Is a thought, Is there a difference In manufacturer? AIRPAX / HEINEMANN I would love to know someone who had a Gen that would not easily Trip the 10Kw Breaker, what manufacturer and part # they had.

 

[GREENMV]

I want to Thank jamawieb for His wisdom, The Idiot award for today go's to Ding, Ding, Ding "MYSELF" I got myself into trouble again assuming my 10Kw Gen was complete with only 40 hours on It and had the correct 10Kw AC box. I got to thinking about what jamawieb said about the CVT1's being different on the 5Kw and the !0Kw so this morning I checked my 10Kw to see the wraps on the CVT1 and It was staring right at me, I had a 5Kw AC box on a 10Kw Gen. No wonder my breaker was tripping. Now I have a brand new breaker for a paper weight. It just go's into Parts Stock? The moral of this story Is, If your Breaker Is Tripping when It shouldn't be, check you AC Box first.

 

[Guyfang]

It maybe not the ONLY reason, but your right, everyone should look. The same thing happened to me with a 60 KW. It was mounted on a large ROWPU. I turned it on, turned on the main circuit breaker for the ROWPU, and all was well. Then a very large pump kicked on, the gen set went into high speed, trying to correct itself for an extremely large load, and then shut down for overload. You would have thought the set was going to jump off the trailer! I figured the load out in KW, and it came to 35 KW. How can it go into overload shutdown? About 3 days later, it dawned on me to check the CT's. I didnt say a word. Changed i,t and slunk out of town.

 

[GREENMV]

Life isn't life unless you learn something every day. I have read the TM's 100's of times, and worked on at least 10 Gen's. but the TM's don't teach experience and that there are smarter people than me.

 

[Guyfang]

Amen!

 

[bones1]

What is the "ac box" you are referring to?

 

[GREENMV]

@bones1, Control box assembly, AC output. The Box the Breaker is located In.

 

[Guyfang]

Every person I have ever heard from, or read comments from, who has great knowledge and experience on the MEP-002A and MEP-003A, has posted at some time on this thread. What do you all think about a document, maybe a sticky, that gives some pointers to people who want to buy one, and do not have the foggiest idea about gen sets? Or just do not know these gen sets? A few basic points, that they should use when looking at one, or after they get one home, and don't know where to start. Please put your comments down here. If you want to contribute, we could do it with PM's. Someone start writing, and send it to someone else. They take a look, and then suggest adding something, changing something or deleting something. Too often we assume people have a good handle on mechanics, and troubleshooting. It not always the case. Doing a few smart things at the start, can save lots of time and money in the end.

 

[GREENMV]

I agree with everything you suggested. This main Breaker Thread started 12/5/10 and that makes a lot of reading material that's not all main breaker. This could be added to the list. My first suggestion to whomever wants a surplus generator thinking there going to get a plug & play at a cheap cost, most likely your not and it always turns out your going to spend more money than you thought you were. You must do your research before you buy a surplus generator. What Model and Kw generator do you need. To the beginners a 3Kw or 5Kw will "Not" power your whole house with a 3 Ton A/C. I would also suggest when you do pick a generator your interested in buying, please read the TM's on It to get a basic knowledge of what your buying. You must also have basic electrical knowledge, Volts, Amps, Resisters, Diodes, AC Vr's, DC Vr's, Transformers, Switches, Gauges, Hookup. Etc. You must also have a basic knowledge of engine mechanics, IP's, Glow Plugs, Starters, Fuel Pump's, Etc. I myself am always learning something new when I work on these Generators constantly, that's what makes it fun, the challenge. But when I get stuck on something That's when I turn to the Pro's on this site for answers or suggestions, trust me when I say they will bail your butt out when needed. You also have to put time and money into the generators to get them back to safe working order. After the initial cost and recovery of the generator or generators, you can easily say your going to spend average $200.00 just for Misc. for each generator. The supplies needed before you can even think about the startup. Batteries, fluids, filters, Parts If needed. As all of us know, parts are not cheap even used parts are not cheap for these. First thing I always do Is turn motor buy hand to make sure it's not locked up. Then there's the time it take's to get one ready to start, I would say It takes me average 2 day's checking the generator out, Cleaning pump filters, flushing fuel lines, replacing missing parts, check all wiring to see if they have been messed with and retighten all connections as I go. Replace all air, fuel, oil filters then refill all fluid's to correct levels. Then when I am ready to start the generator, I give the please work prayer then go from there. It can take day's sometimes to diagnose something that is wrong. There Is a lot of stuff I left out or I could have wrote a book on, but I hate typing. I always tell myself that this Hobby of mine Is Fun. P.S. Never Assume Anything.

 

[Philratcliffe]

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.

You did this on an mep 002? Is it in three phase or single phase mode? I have an 002 with a fresh rebuilt engine and the breaker trips at a very low load of 8 amps.
I only need single phase for my application. So can I switch it to single phase and tie the wires together in the back of the breaker and run a 50amp breaker after the wires leave the generator? Thanks for any info. Phil

 

[Philratcliffe]

It maybe not the ONLY reason, but your right, everyone should look. The same thing happened to me with a 60 KW. It was mounted on a large ROWPU. I turned it on, turned on the main circuit breaker for the ROWPU, and all was well. Then a very large pump kicked on, the gen set went into high speed, trying to correct itself for an extremely large load, and then shut down for overload. You would have thought the set was going to jump off the trailer! I figured the load out in KW, and it came to 35 KW. How can it go into overload shutdown? About 3 days later, it dawned on me to check the CT's. I didnt say a word. Changed i,t and slunk out of town.

Pls excuse my ignorance but what is the CT?
I’m trying to get one of my 002s to carry the max load and my breakernis tripping at only 7/8amps. Thx guys.

 

[Guyfang]

Pls excuse my ignorance but what is the CT?
I’m trying to get one of my 002s to carry the max load and my breakernis tripping at only 7/8amps. Thx guys.

You are in a hurry. Much better to find out what is wrong. It may not be the CB. It might be something as simple as a loose wire. Dirty contacts in the S8. A miss wired gen set. Unless you really KNOW what you are doing, you can really get someone hurt, or destroy things.

Just my two cents worth.

 

[VO1960]

After some digging and redrawing sections of the schematic so I could understand it, I believe the reason R3 has little effect on the generator’s tolerance for startup current surge from a motor load is because all 3 Current Transformers (CT1A, CT1B, and CT1 C) are sending current information to the Breaker’s three trip relays individually.

R3 is the “CB1 Shunt Resistor,” according to the schematic REF DES & DESCRIPTIONS block. But R3 drops the voltage/bypasses the current to only one of the three trip relays. Tolerance to overcurrent spikes in the CT1B circuit can be improved, but there is nothing to reduce the spikes or adjust the trip level in the other 2. While the current monitor from CT1 B can be shunted lower by the setting of R3 counterclockwise (lowering R3 resistance means higher current levels are tolerated because more current that is derived from the load current value will flow through R3 and less will flow into the trip relay), but as CT1 A and CT1 C are also reporting current that travels to the load, they too can rise high enough to trip their respective breaker relays when a motor connected to the outputs is starting up.

I looked, and in all three configurations of the S6 Load Switch, CT1 A, B, and C are sending current and building up voltage in the breaker relay segments that trip when the current in any of the output windings gets high enough. The method that the breaker's trip relay action uses has been well covered in other posts here, but it turns out that current spikes in any one of the 3 of them will trip the respective breaker and then through mechanical linkages the other 2 breakers will also turn off. The only mystery to me is why the designers provided an adjustable resistive shunt to bypass some of the current away from only one of those three trip relays. The manual tells us to set R3 such that it bypasses all but .6 amps into the L3 trip relay at full load in the single phase 120 volt realm. There is no way to adjust the other 2 trip relays.
I'm puzzled why R3 is there at all, given that it only provides relief on one channel. It's not like you could adjust it to trip at a LOWER surge (adjust it to be MORE sensitive). That would make more sense from a protection standpoint. What's the point of making only one channel less sensitive? The other channels still see any higher currents in the load and will trip accordingly.