MEP 804a under voltage after start up

[SQF]

Guy correct me if I’m in error but the 803 and 804 run a different fault board correct? Correct.

If M9 is reading, then you have a load? How much is it reading?

M8. Is your S6 in the proper position?

Yes, it’s connected to a farm building that was drawing. There’s a 240v hot water heater that I’m sure was calling for voltage. M9 was reading around 30-40% if memory serves me.

As for S6, it’s on the L1-L2 position which is where we have our two load lines connected. I don’t think anyone has messed with any of that.

I also confirmed that I have 137vac at the convenience plug which is concerning…

 

[kloppk]

Have you checked to be sure the voltage reconnect board nuts are all secure?

 

[Guyfang]

I should clarify, not sure if this is normal but I step up to run L1&L2 and I’m getting 133vac on one leg and 129vac on the other but 236vac across both. Seems normal for 240 but high on the 120 legs.

Where are you taking these measurement? or are you going by the AC volt meter?

What do you get at TB1-1 and TB1-2? That should be a straight shot out from the Main gen.

L1 and L2. Measure N to TB1-1 and then N to TB1-2. Then Between TB1-1 and TB1-2.

 

[SQF]

I should clarify, not sure if this is normal but I step up to run L1&L2 and I’m getting 133vac on one leg and 129vac on the other but 236vac across both. Seems normal for 240 but high on the 120 legs.

Where are you taking these measurement? or are you going by the AC volt meter?

What do you get at TB1-1 and TB1-2? That should be a straight shot out from the Main gen.

L1 and L2. Measure N to TB1-1 and then N to TB1-2. Then Between TB1-1 and TB1-2.

I took the measurements at the load lugs where our line to the barn is connected. I will remeasure them tomorrow and upload photos of what I’m getting. Thanks for the continued steering of a novice!

 

[SQF]

Could also be K14. The over volt relay. try switching out K14.

I will try K14 later today. Thanks

 

[SQF]

I will try K14 later today. Thanks

Ok, tried swapping a relay out of my 803 for K14, no change. Here are photos of the voltages I’m seeing. Starting to wonder if the VR was bad? Maybe I should go back to the old Libby VR?

One thing I’m noticing, if I hold start more than 2-3sec it gives me an over speed or over voltage fault and shuts down. If I hold it just a second or two it has a slight rpm change but stays running and will produce power. It’s like a hiccup. I’m trying to figure out how to put a video in this thread.

 

[SQF]

Ok, tried swapping a relay out of my 803 for K14, no change. Here are photos of the voltages I’m seeing. Starting to wonder if the VR was bad? Maybe I should go back to the old Libby VR?

One thing I’m noticing, if I hold start more than 2-3sec it gives me an over speed or over voltage fault and shuts down. If I hold it just a second or two it has a slight rpm change but stays running and will produce power. It’s like a hiccup. I’m trying to figure out how to put a video in this thread.

I should also relay. It doesn’t seem to matter whether the fault board is plugged in or not. It matters how long I hold S1 in start…

 

[kloppk]

Adjust the front panel voltage adjust so you get 120 v from a phase to neutral and see if the over voltage fault goes away.

 

[kloppk]

Your voltage readings are correct. 136 volts Phase to Neutral, 137 volts Phase to Neutral and 238 volts Phase to Phase. 137 volts at the outlet is expected.
Remember your 804 is a 3 phase set.
Normally the set puts out 120 volts Phase to Neutral and 208 Phase to Phase.
To run your 240 volt load you've cranked up the AC output to jack up the Phase to Phase voltage from 208 to ~240.
Doing so changes the Phase to Neutral voltages from 120 V up to 137 V which is why you are seeing at the lugs and the outlet.

The Phase to Phase voltage is the square root of 3 (1.732) times the Phase to Neutral voltage.

 

[Guyfang]

Simply turn R1 down the whole way to the left. Then start the set. If it runs, adjust the R1 up to its proper setting.