Mep002 strange voltage issues.. Please help

[CDR]

So my MEP 002 has always been as reliable as a rock today I started up for it's monthly cycle and it would not hold steady voltage. The more load I put it under the higher the voltage went. Turning the voltage knob did very little in fact raised the voltage level when trying to decrease it.

Under 100% load the lowest voltage I could get was 125.5

The stranger part is the volt meter on the motor holds steady and goes up and down when you move the knob. All measurements taking with a kill-a-watt.

I'm guessing it's the voltage regulator I remember there's someone on here who makes new ones could anyone give me his contact information?

Thanks for all the help
Dave

 

[Triple Jim]

Dave, it does sound like the regulator is not doing its job. It supplies current to CVT1 when the generator output voltage needs to be reduced. If it can't supply enough current, the voltage will go up. The more load is put on the generator, the more current the regulator needs to supply. I know this only because I added a regulator output current meter to my front panel, and can watch it change as load changes and the voltage is held steady.

The problem isn't necessarily with the regulator though, it's just likely that it is. It's not inconceivable that CVT1 developed some shorted control windings, for example, but that's not very likely. To rule that out, you could check the winding resistances and compare them to the values in the TM. Also, it's possible that some contacts in the control circuit have developed a high resistance and aren't allowing enough regulation current to pass. The mulit-pin connector on the back of the main control cabinet, for example, might need to be unplugged and cleaned.

I'm just trying to think of things that could cause your problem other than the regulator. I'm the guy who makes new ones, by the way (see my signature).

 

[CDR]

Thank you Jim I think a good spot to start is a new voltage regulator wouldn't hurt to have a backup anyway

 

[CDR]

I received the regulator beautiful construction easy installation! Started up generator worked perfect. After five minutes of running it went back to doing the same thing. So aggravating!

Lowest obtainable voltage 124 either way you turn the dial voltage will increase. Voltage Gauge on the generator shows normal voltage and goes up and down with the dial???

 

[CDR]

It just hit me that maybe I should try a different voltmeter other than the kilowatt

 

[Triple Jim]

If the voltmeter on the generator shows correct voltage, and shows higher and lower voltage with the front panel adjustment, then yes, I'd suspect the other meter.

 

[CDR]

Tested with a fluke and the killawatt is dead on... So confused

 

[Triple Jim]

Check both sides of the 240 to neutral at the main output lugs. That is, L1-L0 and L3-L0, and see when they do as you turn the adjustment knob. Use appropriate caution, of course.

 

[CDR]

Ok I'll give that a shot

 

[CDR]

Same readings... If the CVT1 developed shorted windings would I have a power out put reduction? The generator will still run a 133% load?

 

[Triple Jim]

When you say "Same readings" do you mean that both L0-L1 and L0-L3 go higher when turning the front panel adjustment both higher and lower? If so, that's truly strange.

CVT1 has several functions. Its windings that terminate in X1, X2, and X3 supply AC to the diode bridge, which is what supplies current to the exciter field. Its windings that terminate in C1 and C2 are the control windings. Supplying current through these causes the transformer to put out less current at X1, X2, and X3, which in turn lowers the exciter current and the generator output. This is what the regulator does, and why running the engine slower than 1800 RPM does not put extra load on the regulator, since it has to do less work to control the generator output when it's running slowly.

So if the control windings at C1 and C2 have some shorted turns, for example, you wouldn't be able to control the generator output properly, and the voltage would be too high. So it's possible you have a problem like this, but I don't know how likely it is.

I installed an ammeter in the control circuit through C1 and C2. This is the regulation current from the regulator board. I put it in line with the wire that goes to terminal 17 of the regulator. The current is typically between 100 and 400 mA, depending on engine speed and generator load. If you monitor this current, it might shed some light on what's going on. You can temporarily connect a multimeter there, rather than add a panel meter like I did.

 

[Triple Jim]

CVT1's control winding resistance (C1-C2) should be 9.6Ω, give or take an ohm. That and its other winding resistances are in TM5-6115-585-34 on page 6-15, which is page 93 in my PDF viewer. The C1-C2 winding is pretty easy to measure, since you have to disconnect the wire from only one terminal to measure it.

 

[CDR]

Ok ill measure the C1-C2 and see what it comes out to. I'll also try to film and video so you can see how strange this issue is. Thanks for all the help your a life saver