MEP 804A lots of issues.

[chesauto]

I just picked up two 804A gensets. One has 2600 hrs, starts up runs great, output very good, just a little rusty.

The second I am having issues with. It has 3hrs on the meter and tag says rebuilt at 2.7 hrs in 2011. I installed new batteries, and it would not crank from S1 or Dead Crank switch. I traced that back to the K2 relay, it was a little corroded, cleaned it now starts and runs good.

When first running, the voltage on meter was good but frequency can only be adjusted between 43 and 53 Hz.

Now I get very low voltage amybe 25 and no frequency on the meter. I have tried holding S1 a little longer, upto 20 seconds but unit still has no output and the starter will stay engaged. I checked the MPU and it reads 3.4 volts the same as the good running unit. I will get voltage in Battle Short mode but frequency stays low. I assume that the MPU signal is not being recognized thus no starter disengagement or field flash.

What should I check next? I can't find anything in the TM, I'm sure it there somewhere just not that familiar with them yet.

 

[robertsears1]

I have a A and B model myself. I am not positive but I almost believe these can run at 50 or 60 hz. Drop the control panel down with the set off and see if there is a switch for the hertz back there. Wondering what you are planning to use these for since they are three phase only.
Robert

 

[chesauto]

The switch is on 60 HZ. Under normal startup, I get no voltage or frequency, only in Battle Short mode does the generator work at all.

I am using one to power 3 phase shop equipment at my house. The other is going to a customer to be be used to power 3 phase waterpump motors. Its much easier for him to run power cable into a building than 8 or 10 inch HDPE pipe. Right now he may take a week to setup, a week to tear down and 8 hours of run time.

 

[155mm]

Does it look like the fuel cutoff/ throttle actuator has been removed? That is a pita to get installed correctly if removed.

also, guy posted colored schematic for this jenny. I cant find them now, will look more tomorrow

 

[155mm]

https://www.steelsoldiers.com/showthread.php?148936-All-the-TM-s-you-need-to-work-on-the-MEP-804A


i think mpu voltages need to be lower than 3v, yours might be too close to flywheel.

 

[chesauto]

Throttle actuator looks untouched. As does the rest of the machine.
Today I tried running it in 50hz, but the engine will not crank from the S1 and the over speed indicator lights up. Dead Crank works in 50hz. I moved back to 60hz, reset overspeed and starts up, I have voltage but frequency max out at 53hz. I checked it convenience plug with a meter and I can adjust it from 47hz to 53hz, gauge on machine matches my meter. I can hear that the engine speed is changing as I adjust frequency.

I will add that during first start attempts, the emergency stop was a little touchy. I had to move it around about 30 times to work and now the slightest touch shuts the machine down.

 

[155mm]

i would control exchange stop switch to eliminate that question, or bypass.

did you say you had some corrosion on connectors? i would loosen then tighten every wire and connection i could get my hands on

 

[155mm]

 

[Guyfang]

Throttle actuator looks untouched. As does the rest of the machine.
Today I tried running it in 50hz, but the engine will not crank from the S1 and the over speed indicator lights up. Dead Crank works in 50hz. I moved back to 60hz, reset overspeed and starts up, I have voltage but frequency max out at 53hz. I checked it convenience plug with a meter and I can adjust it from 47hz to 53hz, gauge on machine matches my meter. I can hear that the engine speed is changing as I adjust frequency.

I will add that during first start attempts, the emergency stop was a little touchy. I had to move it around about 30 times to work and now the slightest touch shuts the machine down.

Like 155 mentioned, bypass the S17. Simply connect the two wires to one terminal. Then you can work on the real problem.

The S10, (dead crank) will work in every mode, as long as K2 is good. Since it starts in S10 mode, K2 is good.

When you tried it in 50 hertz mode, the S1 would not let the K2 energize because the over speed circuit was tripped. Why the Over speed came on, is a mystery.

This might require an adjustment at the IP, to boost up the hertz. But first follow the directions below to make sure someone has not knob dicked the A5, (Electric Governor)

View attachment 15-60KW A Model A5 GCU Adj.pdf

 

[chesauto]

I went thru the checks. First, I get 24v on A5-20 all the time start or run. I get 0v on A5-18 all the time start or run. I also get 14VAC at A5 from the MPU .I did the quick Frequency adjustment and now operating at 60hz, it looks like it needed one full turn on A5 adjustment.

The overspeed fault is now in 60hz mode also. At times, I turn S1 to Start, starter engages for a split second then overspeed light comes on and will not crank. Push stop button, pull it back out and unit starts. I swapped S17 from the other unit just to be sure and no change.

 

[chesauto]

I went thru the checks. First, I get 24v on A5-20 all the time start or run. I get 0v on A5-18 all the time start or run. I also get 14VAC at A5 from the MPU .I did the quick Frequency adjustment and now operating at 60hz, it looks like it needed one full turn on A5 adjustment.

The overspeed fault is now in 60hz mode also. At times, I turn S1 to Start, starter engages for a split second then overspeed light comes on and will not crank. Push stop button, pull it back out and unit starts. I swapped S17 from the other unit just to be sure and no change.

 

[Guyfang]

I do not think the over speed problem is specifically a 50 hertz, or 60 hertz mode problem. I think it was pure luck that the first time the faul happened, it was in 50 hertz mode.

Try this. Swap the fault indicator panel. Then see if you continue to get an over speed fault.

 

[chesauto]

I will try that in the morning.
One thing that does not make sense to me, if power to the A5 - 18 excites the field for power generation, I get no power ever on that circuit but unit runs and makes power. Also, when the machine does start, I only have to bump the S1 for 1/2 a second. Any longer and the starter grinds but everything appears to operate normally once it is running.

The other machine I have to hold the S1 for 5 to 10 seconds or it will shutdown. The starter does disengage while I hold S1 for the oil pressure and Hz to build.

 

[Guyfang]

STOP!

You our have a problem with your MPU. Pull it out. Check, clean and properly reinstall. If you need help, say something. Or read the TM. If the end is ground off, get a new one. Any time you get flywheel clash, the MPU is not working right.

 

[155mm]

i think mpu voltages need to be lower than 3v, yours might be too close to flywheel.

see above

 

[chesauto]

I could not find adjustment specs in the TM. Probably the TM I need won't open. What ACV should the MPU be set to?
I checked both machines and they are both just above 3ACV like 3.3 or so.

 

[155mm]

I would remove and inspect, 2-3 vac

 

[155mm]

https://www.steelsoldiers.com/showt...rt-suspect-solenoid-on-side-of-injection-pump



it gives the tm and pg number

 

[mcii]

Easy MPU set up is as follows. Line up the flywheel where a tooth is directly or as best you can, directly, in the center of the hole where the MPU is threaded into. With the MPU removed be sure it is as clean of small filings and anything metallic, thread it into the hole and for reference count the turns using a marks a lot or whatever works for you as you think or experience best. when it [mpu] bottoms onto the tooth, then back out1 to 1-1/2 turns, set the jamb nut crank and measure AC voltage, you already know ballpark range ur looking for, IN is more/higher output voltage, OUT is less or lower AC voltage.. this should settle the mag pick up issue and continue your problem solving efforts and you are assured this in no longer in your area of concern. As a side note you can measure the MPU voltage at the freq controller with the wires hooked up, the volt meter ur using wont burden the voltage enough to cause a significant difference to the controller modual... You don't have to try and hold your meter leads and all the mess it takes, with the wires set and anchored it is easy and you will get solid readings
let us know, best of luck.. mac/mc

 

[mcii]

Chesauto a bit more on the relationship between the MPU and its output voltage, on the speed controller you have several places for multiple adjustments, SPEED is one another is GAIN and might have another STABILITY or such.. when adjusted properly your engine should run very smooth, but to set it up long term, at speed 60 hz 1800 rpm turn the GAIN CW at a near point your engine should begin to move erratic, when you reach this condition, turn back CCW to GAIN until the engine runs smooth and steady. Gain adjustments' are derived from the MPU voltages being supplied to the controller, you can start to see the near symbiotic relationship between these signals.. When you finally set the gain be generous and over travel a bit, don't leave it right at the edge where your steady state becomes stable, these controllers and fuel temps play into the final settings. mac/mc