MEP802A has Phase 3 power but no phase 1 power?

[ECS]

Could someone please help me on where I should I look to correct his problem?

Generator engine MEP802A starts and run fine.

With the switch on any of the Phase 3 settings the meter on the unit shows the generator has power, and myself with a multi meter shows it has power BUT when a load is applied the "short circuit" light come on and turns off the electrical power (engine keeps running).

When the switch is set to either of the two Phase 1 setting the meter on the gen shows no voltage, and a multi meter also shows no voltage.

I would like to get at least the Phase 1 working.

This generator is near new and is from that operation put-away, but has been like this since I recently got it.

I'm wonder in either something is not working or if something was assembled wrong?

 

[Guyfang]

Is this with, or without a load hooked up?

Have you downloaded the TM's from the TM forum?

 

[ECS]

Is this with, or without a load hooked up?

Have you downloaded the TM's from the TM forum?

Without the load hooked up the Phase 1 shows no voltage.

Without the load hooked up on any the phase 3 setting the gen runs ok and produces power on the phase 3 settings.

With the load hooked up the short-circuit light come on as soon as the gen circuit is turned on.

I'll go through the TM's and see what I can find, thanks.

 

[Light in the Dark]

Can you tell me what 'switch' it is you keep referencing?

 

[ECS]

Can you tell me what 'switch' it is you keep referencing?

The switch I am referring to is the one that selects the Phase and legs you want to use. (sorry i don't know it's name).

I did look thought he TM's but I didn't see anything that popped out at me.

It is this one circled here. (not my gen just example of the switch).

 

[Light in the Dark]

Thank you for clarifying. This switch only tells the gauges what to show. Your phase selection switch is on the wall behind these gauges (where the voltage regulator is mounted). The phase switch should only be moved when the machine is OFF... no exceptions.

 

[ECS]

Thank you for clarifying. This switch only tells the gauges what to show. Your phase selection switch is on the wall behind these gauges (where the voltage regulator is mounted). The phase switch should only be moved when the machine is OFF... no exceptions.

Thanks !

Hopefully that is my issue!

 

[Light in the Dark]

If you are getting a short circuit light, this knowledge will not change anything. I think you need to get a GOOD contact spray cleaner and when the machine is off, take the roof off and deoxidize the phase selection switch and ALL switches and contacts in the machine. Corrosion in the switches is a big problem with these sets, and can sometimes cause phantom issues.

With that said, you should consult the -24 manual for your machine, and how to test the 'SHORT CIRCUIT/OVERLOAD RELAY'.

 

[Mullaney]

If you are getting a short circuit light, this knowledge will not change anything. I think you need to get a GOOD contact spray cleaner and when the machine is off, take the roof off and deoxidize the phase selection switch and ALL switches and contacts in the machine. Corrosion in the switches is a big problem with these sets, and can sometimes cause phantom issues.

With that said, you should consult the -24 manual for your machine, and how to test the 'SHORT CIRCUIT/OVERLOAD RELAY'.

.
Gotta ask... Do you have a preferred spray contact cleaner? I am down to my last can of whatever it is that I bought last time.
It might be time to ORDER the good stuff rather than whatever is on the shelf at the local NAPA...

 

[Light in the Dark]

I've had real good luck with this (and I tried it on a recommendation found here in SS): https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU

Been using it for the last 3+ years with no complaints at all.

 

[Guyfang]

OK, before we go any farther.
It would be good if you read the operators TM at least twice before fooling with the set tooooooooo much.

Now, lets go back a step. Put the S8 switch in the 3 phase position. Start the set with no load hooked up. When its running, and your handy multi meter is hot in your hands, measure from the LO load terminal to all of the 3 phases. Make sure you are getting voltage. Then turn on the S5 switch, to close the K1. Do you get a short circuit light? Or, will the set run along just fine with the DS7 brightly shining in your eyes? If it the set continues to run right, turn off the set. Hook up the load, and try it again. If the Short Circuit light comes back on and the set shuts down, you have the load hooked up wrong, or there is a problem in your load.

Yes, the above is written in a foreign tongue. That forces you to look at the schematics to find out what I wrote, and makes it much more easy for people to help you.

 

[ECS]

thanks

 

[ECS]

Thanks.. that problem has been resolved and I have a new one that is different.

 

[nextalcupfan]

I've had real good luck with this (and I tried it on a recommendation found here in SS): https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU

Been using it for the last 3+ years with no complaints at all.

I second using Deoxit, it's basically at the point where every time I take anything electrical apart I spray it with Deoxit.
I've watched it basically melt green corrosion while not harming anything else.
A small amount of abrasion helps too, like a pointed nylon bristle brush.

 

[Light in the Dark]

Thanks.. that problem has been resolved and I have a new one that is different.

Can you tell us what/how it was resolved?

 

[ECS]

Can you tell us what/how it was resolved?

The phase-3 vs phase-1 problem was me, I didn't know the phase-3 and phase-1 controlling was the one behind the panel, VS the switch that is on the panel and lets you select phase-1 and phase-3.


THanks for your help on that !

Now when I put the switch (behind the panel) on Phase-3 is shows 208 volts, when on phase-1 120 volts it shows 120 volts, and when on phase-1 120 / 240 volts it shows 240 volts.

BUT my new problem is as soon as I close the circuit (the green light) when on Phase-1 with 120 / 240 selected the engine bogs down and it sounds like a clutch slipping, voltage goes to zero and the green light turns off.

When in Phase-3 if I close the circuit the engine bogs down and the voltage drops and the red-light short circuit comes on "ONLY if the ground and neutral plate are bonded". If I remove the bonding plate that issue does not happen.

None of this is under load. Is is ONLY closing the circuit. Prior to closing the circuit (green light) everything looks good. Both Phase-3 and Phase-1 voltages look good prior to closing the circuit "with no load".

also.. When the Phase-1 just 120 volt is selected, when the circuit is closed no issues occur and the unit produces 120 volts even under load without issue.

The purpose of this unit is for Hurricane backup power so I want Phase-1 and the 120/240 working.

The unit looks like near new.

 

[Light in the Dark]

As this is a brushless head, and the rotor is supported by a central bushing... there are no parts which contact. It sounds like you have an issue with either the rotor or the stator (my gut feeling is you have a winding problem in the stator). I would not turn this machine on again until more of the knowledgeable guys here chime in on this.

Im decent with these machines, but there are others (@kloppk ) who are much better on the electrical diagnosis side of them.

 

[KN6KXR]

I work on a lot of generators but not military ones. Nonetheless they all operate based upon few variations of the same principles. Post a schematic of your unit I may be able to offer some constructive advice.

 

[Guyfang]

OK. Stop. If the problem is not a problem, until you close the out put circuit breaker, (K1) then the problem is not your main gen. Its from the K1 to output terminals. Thats the only thing that changes when the set is running no load, and running with load.

What kind of a load are you running?
Where is it hooked up?
How is it hooked up.
Pictures might give up a hint.

But I dont think you have a main gen problem.

 

[kloppk]

Sounds like one of the leads running from K1 to the output lugs has chaffed through the insulation and is shorting to the chassis. The clue here is removing the bonding bar makes the problem go away. Removing the bar eliminates the path from the chassis to Neutral.

Pop the top cover off and carefully inspect the 3 leads from K1 and check their run from there to the lugs.