MEP-802a contactor

[johnnypower]

just acquired a mep802a from GP . test ran great . starts and runs , had power at convenience outlets but not at terminal lugs . Started to think the worst but then switched to think logically and realized contactor may not be closing . tested switch , checked relays , but green closed indicator would only light when testing (depressing) . activating switch to close A/C interrupter or open it had no audible response ,or electrical response on contactor . after removing top cover to access contactor and running written tests on contactor , last test was to jump power to x terminal from crank solenoid . Bingo ! audible response , visual response on continuity tester on each leg of contactor . Activated A/C interrupter switch on dash panel and long behold , it works fine now . was contactor stuck ? No corroded wires or terminals , no loose wires or screws . These things are similar to contactors in engine driven welders and I have never seen one wear out or go bad . Pressure washed unit and let sit overnight , tested again works fine ! I was hoping water and detergent was gonna help induce another malfunction but unit works great . Has anyone else experienced contactor issues or was this just a fluke ? Dont know if it was a wire or contactor issue . Don't want to just throw parts at it and guess it will be fine . I can always pull power from input side of contactor in an emergency , but just hate to have to pull that cover off with its many screws in a storm . And Yes , a 10kw load will stall this unit . Load tested at 105% on 120/240 1ph and unit ran fine , huffed a little black once load was increased to 110% up to 120% then RPM's started to decline fast as load was increased and unit stalled at 130% .

 

[Ray70]

You are probably correct in thinking the contactor was stuck, if you do a little looking around you will see that several of us have used the rubber mallet rework to "Fix" stuck contactors in a pinch.
If everything inside is clean and corrosion free I would say put it back together ( ensure the cover gasket is in tact ) and continue to test it.
If it hangs up again you will want to further investigate it's internals, but the rubber persuader technique will 99% of the time get you back under power in an emergency.
And I bet everyone else also wants to ask.... Why or how do you know 10Kw will stall your 5Kw rated generator?? Was that an accidental overload or intentional? Although it would expect it should have bogged badly and eventually tripped the overload. It should not have stayed connected and stalled the engine.
It sounds like there is a possibility that either your overload is not functioning correctly, or the overload relay attempted to disconnect the contactor but it stuck ON.?? You may want to further investigate if there is an issue with the fault control panel or the overload relay.
BTW, power from the circuit interupt switch flows through the overload relay before reaching the AC contactor, so an intermittent problem with the overload can show itself as an AC contactor that will only close while you are holding the switch in the up ( on ) position.

 

[johnnypower]

You are probably correct in thinking the contactor was stuck, if you do a little looking around you will see that several of us have used the rubber mallet rework to "Fix" stuck contactors in a pinch.
If everything inside is clean and corrosion free I would say put it back together ( ensure the cover gasket is in tact ) and continue to test it.
If it hangs up again you will want to further investigate it's internals, but the rubber persuader technique will 99% of the time get you back under power in an emergency.
And I bet everyone else also wants to ask.... Why or how do you know 10Kw will stall your 5Kw rated generator?? Was that an accidental overload or intentional? Although it would expect it should have bogged badly and eventually tripped the overload. It should not have stayed connected and stalled the engine.
It sounds like there is a possibility that either your overload is not functioning correctly, or the overload relay attempted to disconnect the contactor but it stuck ON.?? You may want to further investigate if there is an issue with the fault control panel or the overload relay.
BTW, power from the circuit interupt switch flows through the overload relay before reaching the AC contactor, so an intermittent problem with the overload can show itself as an AC contactor that will only close while you are holding the switch in the up ( on ) position.

Intentional overload using a 10kw resistive load bank . Did not let it stall completely , just increased load till unit slowed to about 500rpm . Thick heavy black smoke but overload did not pop . After I get it all serviced up with new filters , fresh oil and fuel lines I’ll see if I can get the overload to pop . Contactor seems to work fine now .

 

[gelane]

Intentional overload using a 10kw resistive load bank . Did not let it stall completely , just increased load till unit slowed to about 500rpm . Thick heavy black smoke but overload did not pop . After I get it all serviced up with new filters , fresh oil and fuel lines I’ll see if I can get the overload to pop . Contactor seems to work fine now .

Why do people thinlk they have to load these things
to try to kill them ?
Do you run your car wide open all the time ?
Do you own other equipment ? Do you run your
tractor wide open ?.....
I just don't get it.
My 803 has never been run over 80% and it runs
and operates fine with no problems.
But that's just me.

 

[johnnypower]

Why do people thinlk they have to load these things
to try to kill them ?
Do you run your car wide open all the time ?
Do you own other equipment ? Do you run your
tractor wide open ?.....
I just don't get it.
My 803 has never been run over 80% and it runs
and operates fine with no problems.
But that's just me.

Don’t want to rely on an unproven genset just like I wouldn’t go to battle with an unfired weapon . Come to find out now I tested it , we now know overload is not working

 

[Dewie38]

I hate to tell you but you now know nothing.
The overload trip is over current if you use a resistive load bank then you would have to put to much resistive load on the set to get to the over current level.
The over current trip point is 130% of rated current and the relay trips in 8 +/- 2 minutes, anything over 130% the trip time is inversely proportional to time so the more current you apply the shorter the trip time.
All you're gonna accomplish with putting so much resistive load on the set is kill the engine.

 

[Dewie38]

(anything over 130% the trip time is inversely proportional to time.)
I meant over 130%, trip current is inversely proportional to time.

 

[johnnypower]

130% , so at sea level rated is 26 amps at 240v , overload will not pop until load is in excess of 33.8 amps ? That little Lister engine would stall right out with that load on it for 6-10 minutes .

 

[Dewie38]

You cant increase the current that high using resistive load only or the engine will stall.
You need reactive load to do that.

 

[johnnypower]

I fix lots of small portable gasoline gensets at work and only have a 15kw resistive load bank mainly for testing engine performance on units . Just like in the days of old we used PTO dynos to test and tune tractor engines . This is my first experience with a MEP type unit . As far as engine performance do you think this little lister is up to snuff falling sharply with a slight overload ?

 

[Dewie38]

Spec limits on Max power (kW) is 110% of rated kW on all TQG sets. Over load is current.
So if you can get 5.5 kW then the set is operating as it was designed to.

 

[Ray70]

Not sure I quite understand Dewie's previous reply....
On an 802, the 5Kw mark is at 80% on the load meter, and I thought the 802's are rated at 26A at 240V , so wouldn't that be 6240W ( at 5000' 100F or whatever condition is listed on the data plate ? )
Maybe I am misunderstanding your statement, but 5.5Kw seems a bit low for an 802 I think.
Or is the 5.5Kw related more to trip current under reactive / inductive loads, than maximum available output?

 

[Guyfang]

Intentional overload using a 10kw resistive load bank . Did not let it stall completely , just increased load till unit slowed to about 500rpm . Thick heavy black smoke but overload did not pop . After I get it all serviced up with new filters , fresh oil and fuel lines I’ll see if I can get the overload to pop . Contactor seems to work fine now .

No problem fixes itself. You can take the time on a sunny day, to remove the K1 and take it apart. Clean it, and put it back together and in the set. Or, one fine night when its dark and raining cats and dogs, you will find yourself doing this. Fix it. Or do not complain, when you are holding a flashlight in your teeth, and fumbling around.

Open to see comments

 

[Dewie38]

The begining of this thread was about trying to overload the genset with resistive load.
You cant get to the overload current trip point with resistive load only, period.
5.5 kw is the spec limit for kW load, nothing to do with reactive load, current load or overload.
MIL DTL 53133 says to perform test method 640.4 max power at 110% rated kW.
That's all they want it to do, whether anyone thinks that's not enough or not.
It may take as much as 125% rated kW but they didnt want to kill the engine so 110% it is.
Dont do something its not designed to do and then think something is wrong with your set.

 

[Squarefour]

just acquired a mep802a from GP . test ran great . starts and runs , had power at convenience outlets but not at terminal lugs . Started to think the worst but then switched to think logically and realized contactor may not be closing . tested switch , checked relays , but green closed indicator would only light when testing (depressing) . activating switch to close A/C interrupter or open it had no audible response ,or electrical response on contactor . after removing top cover to access contactor and running written tests on contactor , last test was to jump power to x terminal from crank solenoid . Bingo ! audible response , visual response on continuity tester on each leg of contactor . Activated A/C interrupter switch on dash panel and long behold , it works fine now . was contactor stuck ? No corroded wires or terminals , no loose wires or screws . These things are similar to contactors in engine driven welders and I have never seen one wear out or go bad . Pressure washed unit and let sit overnight , tested again works fine ! I was hoping water and detergent was gonna help induce another malfunction but unit works great . Has anyone else experienced contactor issues or was this just a fluke ? Dont know if it was a wire or contactor issue . Don't want to just throw parts at it and guess it will be fine . I can always pull power from input side of contactor in an emergency , but just hate to have to pull that cover off with its many screws in a storm . And Yes , a 10kw load will stall this unit . Load tested at 105% on 120/240 1ph and unit ran fine , huffed a little black once load was increased to 110% up to 120% then RPM's started to decline fast as load was increased and unit stalled at 130% .

BEHIND THE INSTRUMENT COVER IS THE 3 PH TO 1 PHASE SWITCH

 

[Guyfang]

Squarefor,

Forum rules might be a good idea for you to take a look see at. Writing all in capitals, and I have looked at 3-4 threads you have posted in, is not allowed. Yes. every once in a while, a little bit. I am one who often writes a word or two in Caps, but not whole messages.

 

[Squarefour]

Squarefor,

Forum rules might be a good idea for you to take a look see at. Writing all in capitals, and I have looked at 3-4 threads you have posted in, is not allowed. Yes. every once in a while, a little bit. I am one who often writes a word or two in Caps, but not whole messages.

Got it, I think I have it cleared up now. Sorry everyone

 

[Guyfang]

Your good! Thanks for the quick response!