Mep-004 trips dc breaker

[Mattell]

Hi Folks,

My mep-004 w/ask is tripping the 7.5 amp dc breaker after I close the a/c breaker to my building. Takes a few seconds then the breaker pops and the unit stops running. Restarts after resetting.

Can anyone think of a common problem these machines have?

After about 50 hours of use on a 1100 hr machine. I have replaced the fuel pumps, and need a day tank switch. Day tank failed the test in the manual, I checked this after finding the original pumps burned out. Machine has run maybe 20 hours since new fuel pump. I have done a visual inspection for shorted wires, found none. I haven't removed the special relay box to do an inspection though, looks like a pain. Any issue's with these due to vibration?

I wish there was a deep sea retrofit so I could get rid of allot of the obsolete hardware.

Thank you in advance for any help guys.

Regards, Mattell

 

[Mattell]

Also, I am located in Ulster County NY. Does anyone have a good reference for a tech in the area. Zip code 12528.

 

[Suprman]

Is the unit grounded properly? Maybe you have a potential feeding back somewhere. Check the power output connections it's easy for a wire to rub a bit and cause problems. Did you try disconnecting from the building and running it? Maybe you can connect a small load like a heater or something and see what happens. There is hardware out there you can use to mod an update of sort. I personally think it's cheaper to buy a modern gen if you want the newer route. But I have also found the newer gens are harder to fix.
Will

 

[R Racing]

Did you try operating the braker with no load. like disconnecting your output cables and have the generators by itself, and see if it still does it?

 

[PeterD]

Agreed, run without a load and see what happens.

Then I'd stick on a DC clamp-on ammeter on the wire to the breaker and measure the current. It is possible the breaker is defective, and tripping at a lower amperage than spec'ed.

 

[Mattell]

Thanks for the helps folks. This evening I went back and let the gen set run for awhile hoping it healed no such luck. Due to the late hour and temps I didn't do any testing. Tomorrow evening I hope to disconnect from the building first and operate the unit. The ground was still solid in the ground and tight connections. I will check the the amp draw on the breaker as well, pending I haven't frozen out there with this cold snap. I will post an update.

 

[1800 Diesel]

Possibly something amiss in the main load contactor? Could be the actuator coil is pulling too many amps & causing the DC breaker to trip. If I was nearby I could loan you a spare to test with.

 

[Mattell]

Got a few minutes tonight to work on the unit.
First I started it to make sure it didn't heal, no luck and tripped the breaker.

2nd. I disconnected from the building and started her up, still tripped the breaker when I tried closing the main.

3rd. Took a chance because I was running out of time. I disconnected the plug on the main load contactor, started and tried to close the main, hit switch several times and breaker didn't pop.

This only proves that the problem is on that circuit including the main contactor itself. I looked in the several manuals i have down loaded and there wasn't a good trouble shooting spec for this. Tomorrow during the day I was going to put the amp meter and see just how much power it's pulling to make sure the dc circuit breaker isn't defective. If the draw is over 7.5 amps would this indicate a bad coil in the contactor?

Is this common, do the coils and solenoids get tired on these machines? I wish I knew what spares they bring with these things when deployed. I am sure some one was keeping track of rate of failure somewhere.

 

[R Racing]

I'll have to look at mine . I didn't think the coil for the main contactor was DC but I could be mistaken?

 

[1800 Diesel]

I'll have to look at mine . I didn't think the coil for the main contactor was DC but I could be mistaken?

I haven't checked the wiring diagrams but I have engaged these main load contactors with the sets not running. (It's helpful when you can actually hear it closing.) I also haven't measured amp pull when the MLC is being engaged, but Mattell could do this as a check to see if it's pulling more than the 7 1/2 amps of the DC breaker's rating.

Kevin

 

[PeterD]

... If the draw is over 7.5 amps would this indicate a bad coil in the contactor?

Is this common, do the coils and solenoids get tired on these machines? I wish I knew what spares they bring with these things when deployed. I am sure some one was keeping track of rate of failure somewhere.

No, you can't make that assumption. However, I believe you can disconnect the contactor's coil and that would be a start on diagnostics.

However even if you disconnect the coil and it doesn't trip the breaker, that doesn't mean the coil is bad! It could be you have a high current draw elsewhere, at about 7.5 amps, and the additional load of the coil is tripping it.

 

[Mattell]

This morning I was planing on checking the current on that breaker first and see how much current is tripping the circuit. If DC breaker working correctly I wanted to start isolating the draw from the genset control panel. Hoping it will be easier to separate the DC coil circuit that goes main contactor there by going inline from the open/close switch. Is there a relay that holds the coil closed until opened by the switch or shutting the machine off?