MEP-002A and -003A main breaker

[3dAngus]

Good to know Munchies. Keep in mind, my work or investigation is incomplete. The others here are saying it won't work with theirs. I believe them, but wish I could find or someone could identify the specific solution to the problem, where we only have the problem cited, thus far, in this thread.

I'm on watch for this thread in case someone goes to Lowes or their favorite electrical provider and identifies a better or at least a different set of salient characteristics, on their newly installed and tested three phase circuit breaker. It is good to know someone can start a compressor off a 2.5 ton without issue. I was thinking, based on reading this thread, the problem would be consistant with all MEP-002s, so I especially appreciate your comments.

 

[dependable]

I'm following this. Learned something about it when my new 003 would trip breaker at less than 100% load. The breaker is the same NSN for the 002 as the 003, from what I can tell from TMs and by comparing actual parts. Wouldn't the R-3 circuit preclude just putting in a standard breaker? I know it relates to a couple of things in output box and control board. There is a 'feedback' wire on each of the 3 poles on breaker, besides the normal input and output.

 

[Munchies]

BOTH 002 and 003 have the same NSN and part number for the breaker.

 

[Triple Jim]

Angus,
Surprised to see so many problems. I can start my small 2.5 ton central a/c with the blower already running with my 002A. The 003 doesnt even fart.

The way I understand the original breaker, if the fluid were to leak out, it would trip very quickly, without the time delay feature. I'm betting that the ones that won't start big motors have something like that wrong with them. My 003A starts an industrial 5hp air compressor easily, while powering the rest of the house.

 

[Isaac-1]

It seems simple enough to feed a separate breaker by tapping into the line side of this breaker, and abandon it in place. Mount the new breaker in an external breaker box mounted to the side of the control box or output box. Maybe even some other place depending on your intended use, the NEC code requires a breaker to be located at, but not necessarily on a a standby generator, and that it be sized larger enough to protect the wiring it feeds, so using a larger than "stock" breaker would not be an issue if your downstream wiring is big enough. The NEC does not specify a distance for at the generator, but within 6 feet of smaller generators is usually accepted, although there could even be argument that at the nearby feed box counts, which would be nice if you are using a breaker interlock type transfer switch. Until fairly recently there was no code requirement for a breaker to be used at a generator at all, that is why so many older commercial sets that we see for sale don't have breakers installed, even though it has always been considered a good option. When it comes down to it the electrical code use of breakers is always set up to protect wiring with the idea that any device is always being fed by an infinite bus (power grid), this is simply not true in the case of generators as they simply don't have the power available to damage appropriately sized feeder wires without first killing themselves.

Ike

 

[cuad4u]

As most everyone who reads this site knows, several months ago I bought several MEP generators (3 each 002A and 1 each 003A) that I have been trying to get going. I have finished 2 of the 002A's. My current project is the 003A. The 4th 002A has served as a parts donor. The 003A is finished but it definitely needs a new voltage / phase selector box because the selector switch is stuck in the 3 phase position and I broke it while trying to get it to move over a period of 3 weeks.

Several weeks I purchased a BRAND NEW MEP 003A voltage / phase selection box. It even has an engraved plate rivited on the side that states it is for the MEP 003A 10KW Generator. I mean it is brand new old stock that I took out of the original sealed military box. It even has a GFI protected convenience outlet. I don't want to mention how much I paid for it.

With the brand new voltage / phase selector box installed it runs a 4KW 240V electric heater. It starts and runs a single phase 1HP 240V exhaust fan in my shop. However when I put any continuous load more than around 25A or any load that requires a fairly high starting current, the main circuit breaker in the brand new box trips (opens).

I tried to start and run a single phase 240V 3HP well pump, a single phase 240V 5HP 175PSI Ingersoll Rand air compressor, and a 2 ton heat pump. Within a couple of seconds after I applied any of these loads the main circuit breaker in the brand new box tripped (opened).

This past weekend a friend loaned me a well used, beat up, 003A voltage / phase selector box that is one of his spares. We installed it in my 003A generator and when using the spare voltage / phase selector box my 003A generator easily starts and runs any and all of the above mentioned loads.

When we removed the old beat up spare "box" and reinstalled my brand new "box", the generator would not start or run any of the loads mentioned above that started and ran easily when using the old beat up box.

I visually checked the brand new box and I mean it is brand new. There are 4 wires around each CT as the 003A box has. There is a metal plate rivited to the box stating it is for the MEP 003A generator.

Obviously something is wrong in the brand new box that causes the main breaker to trip at current much less than the 003A generator can supply. I did not try to adjust R23 yet.

Any ideas or what am I missing?

Thanks

 

[Triple Jim]

As I understand the breaker, it is a complicated one with a fluid damped delay mechanism and a magnetic trip mechanism. Even though it's never been used, if fluid leaked out over the years, is could lose its time-delay ability. Tripping with a steady 25 amp load is a different story, though. It would be interesting to swap breakers instead of the whole box, and see if that also fixes the problem.

 

[dependable]

I was having same problem this summer with an 003 that tripped at around 30A. I did swap breakers out of a 002 that would bog down on overload without tripping breaker. I have since adjusted the R-3 on that 002. There was something else wrong with the control box circuitry, it was not the breaker. I installed another used control box on the 003 but have not tested it yet, ran out of playtime.

 

[glcaines]

As I understand the breaker, it is a complicated one with a fluid damped delay mechanism and a magnetic trip mechanism. Even though it's never been used, if fluid leaked out over the years, is could lose its time-delay ability. Tripping with a steady 25 amp load is a different story, though. It would be interesting to swap breakers instead of the whole box, and see if that also fixes the problem.

Ditto. I would try swapping the breakers. That would eliminate everything in the box except the breaker. I would guess it is a defective breaker. My 003 never trips a breaker, even when pulling a load close to stalling the engine. It will also start my 5 hp compressor without difficulty.

 

[peapvp]

Good morning,

I have read the original post from sewerzuk. I have not read everything single post due to time constraints and I hope I am not going to repeat something which has been already said or discussed.

These breakers are a breed in their own right. The functionality is actually quite simple. They are 12 pole Breakers. As sewerzuk reported correctly they have 6 large posts for the main circuit and 6 smaller post - hence the name 12 Pole Breaker.

The 6 smaller Posts are used to either series and/or parallel the three breaker elements for load sharing and to increase or decrease the current trip point.

The 6 smaller Posts are controlled when the Output Selector switch is moved -

At 120 VAC single phase all three breaker elements are paralleled internally - the two breaker elements for L2 and L3 are also removed from the large terminals.

for 120/240 Split Phase, two elements are paralleled and the paralleled pair is connected then in series with the 3rd breaker element - This allows for a higher Voltage to accommodate the 240 VAC, however the series ed element will trip much faster in the 240 Volt Configuration.

Each element has app a 38 Amp Trip Point (MEP003A 803A)

so in the 240 VAC Split phase configuration you may have a problem when starting large inductive loads such as squirrel cage motors because of this internal configuration of the breaker.

 

[dependable]

Thanks Peter, that's interesting about the paralleling in the breaker.

Another note, on the output box that I was having troubles with, changing the R-3 adjustment made no difference, it was holding at about 3 times the suggested setting of .6 amps even though I was moving the R-3 shaft. (as per test page 9-2 in TM5-6115-585-34). I did swap breakers as noted and also the R-3 itself ( tried 2 R-3s out of 2 working units).

In the case of my 003, something else was wrong with circuit. Just suggesting to check the R-3, which is easy, before swapping breaker, which is a somewhat tedious job.

Also, if any of you with better understanding of circuitry could figure what was wrong so that changing the R-3 setting would not change test output amperage, it would help me and probably others.

 

[peapvp]

"Another note, on the output box that I was having troubles with, changing the R-3 adjustment made no difference, it was holding at about 3 times the suggested setting of .6 amps even though I was moving the R-3 shaft. (as per test page 9-2 in TM5-6115-585-34). I did swap breakers as noted and also the R-3 itself ( tried 2 R-3s out of 2 working units)."

You may want to check CT1 A, B and C - this is a Current Transformer and CT31 and CT32

CT31 and CT32 maybe inside CB1 and CB1 would have to be disassembled for this purpose. Did you check the contacts of S6 [ AC RECONN SW]?

If S6 has bad contacts (Dirty, burned etc) then adjusting R 3 will make no difference.

 

[dependable]

I did check CT1 and resistance was in spec. Reconnection switch on this unit looks new and freshly installed, making me wonder if it was installed correctly.

I don't know about CT31 and 32, will have to look into that.

 

[peapvp]

R3 is in series with a NC Contact of S6 - however if this contact is completely open then would not be able to measure any Current as instructed in the TM

 

[ashwood486]

Hello, I just joined the forum after reading the post on the Mep002a generator. I'm having the same problem with the Breaker cutting out with motor and compressor start up. I have been able to use everything in my home except the A/C , including the electric 50gl hot water tank and the electric clothes dryer, each being used and different times. I notice the breaker for the generator is the rated for the same as my A/C unit, but will not come close to allowing it to start. I have an idea of bypassing or adding an additional breaker for just the 6 main power wires inside the 002. I've been an HVAC tech for 25 years and understand the soft starting options, I know the generator will handle the running amps of 18-21 from my A/C with no problem if I can overcome the weak start up problem.
Has anyone ever attempted this before?
I realize the 002 breaker has other things its doing with control wires so I'm thinking to just unhook the main voltage wires and go to a new breaker for just the main power wires.
Thanks to everyone for all your post's they have helped me a lot.

 

[Speddmon]

I was having same problem this summer with an 003 that tripped at around 30A. I did swap breakers out of a 002 that would bog down on overload without tripping breaker. I have since adjusted the R-3 on that 002. There was something else wrong with the control box circuitry, it was not the breaker. I installed another used control box on the 003 but have not tested it yet, ran out of playtime.

I just came back through and read this post. You do realize that the main breaker for the MEP-002a and MEP-003a are DIFFERENT, right?

That would explain why you tripped it out at only 30 amps regardless of where R3 was adjusted to.


Even though they look the same, the 002a has a contact rating of 50 amps vs. the 003a rating of 100 amps. This isn't the issue though. They each have a trip coil inside for the overcurrent trip setpoint. They are different setpoints. The R3 adjustment just fine tunes the set point, it won't allow it to go as far as needed to allow an 002a breaker to handle the full load current of the 003a.

 

[ashwood486]

I must be missing something because I still am searching for the R3 adjustment procedure. can anyone help.

I'm looking into a softstart for my A/C , or a separate breaker, or just changing generators to the 10kw model. I really like the low fuel consumption of my 5kw, its hard to beat lol.
I also was lucky enough to purchase a MEP002a with only 1 hour on it. I have since put 53 hours on it and am very happy with it.

 

[Speddmon]

I've been an HVAC tech for 25 years and understand the soft starting options

Then you know that the hard start kit is your cheapest and easiest option.

Just like troubleshooting electricity, or A/C units. Start simple, then move to the more complicated issues. Start with the hard start kit and see if that accomplishes your goal before you re-engineer the generator.

 

[dependable]

I just came back through and read this post. You do realize that the main breaker for the MEP-002a and MEP-003a are DIFFERENT, right?

That would explain why you tripped it out at only 30 amps regardless of where R3 was adjusted to.


Even though they look the same, the 002a has a contact rating of 50 amps vs. the 003a rating of 100 amps. This isn't the issue though. They each have a trip coil inside for the overcurrent trip setpoint. They are different setpoints. The R3 adjustment just fine tunes the set point, it won't allow it to go as far as needed to allow an 002a breaker to handle the full load current of the 003a.

That is what I would have figured too, but the parts TMs list them as having the same NSN, so I thought it was controlled by R-3 setting. Is the TM wrong? (would not be the first time). Is there a way to change set point? Others seem to have agreed it is the same. I really don't know.

 

[ashwood486]

Then you know that the hard start kit is your cheapest and easiest option.
I completely agree with you, under normal circumstances. However I happen to have several good 3 pole breaker's and weather proof enclosures just laying around. I also have some fusible disconnects not in use. I will have to purchase a hard start or even the newest option which is advertising the largest reduced amperage draw , a soft or slow start kit. Which comes in around $325. It works similar to a slow start wood router.
I've been trying to explore all my options and gather as much information before making any changes. I never like to start rethinking or making changes to something that's working good and has the track record these sets have.

my current almost new A/C unit is working fine on a normal household 30 amp breaker and after reading about the breaker troubles thought to look into the generator breaker issues a bit deeper.
Thanks for helping and all the valuable information that is continually offered