Mep 804a overspeed issues

[jmenende]

So this is the first time i have seen this issue and I wonder if any of you have run across the same problem. Got an 804a i just got running and it starts up no issues. The moment i hit the contactor close i sense a small draw in power but nothing is connected. If i then open the contactor i get an overspeed idiot light and it turns of. I have played with the overspeed knob on the governor but it makes it worse. Im checking the mag pickup tommorow but i rather go with other alternatives to check as well and thats why i ask.

 

[kloppk]

Have you monitored the output frequency while doing this? Use an external meter and don't rely on the sets frequency meter. Does the RPM stay steady? Does the frequency stay steady?

 

[jmenende]

Have you monitored the output frequency while doing this? Use an external meter and don't rely on the sets frequency meter. Does the RPM stay steady? Does the frequency stay steady?

I always use mi digital miltimeter. When i cycle the contactor it can give crazy readings 70+hz

 

[kloppk]

Does the audible RPM jump up at the same time?

 

[jmenende]

Does the audible RPM jump up at the same time?

Yes, when the contactor is closed.

 

[kloppk]

A long shot but maybe check if the MPU is adjusted properly.

 

[jmenende]

Yep, the magnetic pickup is on schedule 4 tommorow.

 

[jmenende]

A long shot but maybe check if the MPU is adjusted properly.

So i checked the mpu, took it off and reinstalled at 30vac. The unit cranks right up. Someone had previously checked the contactor and the transformer wires since they were marked and the transformer wires were spun ugly. I redid them just like the factory and made sure they all had 3 turns and were on snug. Then i took apart the reconnection board and made sure all cables were in the correct lug... they were. Im going to check the governor next since i ran out of ideas and the overspeed idiot light comes on after the contactor switch is toggled a few times and the engine revvs. Apart form that she runs fine and produces power.

 

[Guyfang]

And is there a load hooked to the set, when you toggle S5 to close the CB?

 

[jmenende]

And is there a load hooked to the set, when you toggle S5 to close the CB?

Nope, no load connected.

 

[jmenende]

Today I ran the unit at full load for an hour. After that, the issue was still there but it was not as rough as before. I can apply a full 18kw load to the unit with the press of a button with my load bank and it takes it with out a hitch, The funny thing is the when I close the contactor its only a slight increase in revvs but when I open it, thats when it overspeeds. I have since adjusted the overspeed knob on the governor and that has made the problem less noticeable.

 

[Guyfang]

So i checked the mpu, took it off and reinstalled at 30vac. The unit cranks right up. Someone had previously checked the contactor and the transformer wires since they were marked and the transformer wires were spun ugly. I redid them just like the factory and made sure they all had 3 turns and were on snug. Then i took apart the reconnection board and made sure all cables were in the correct lug... they were. Im going to check the governor next since i ran out of ideas and the overspeed idiot light comes on after the contactor switch is toggled a few times and the engine revvs. Apart form that she runs fine and produces power.

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