Mep005 Not Producing

[Old Man]

My Mep005 generator has stopped producing power. Only has 80 hours on it. after it quit I did get it to pick up one more time by holding the start switch longer. But now it won't pick up and produce no matter how long I hold the start switch. Any idea what I need to do or replace?

 

[Guyfang]

Old Dude!

Have someone measure with a multimeter at the 110 volt outlet, while you hold up the start switch. Do you get absolutely no voltage? You should get at least exciter voltage. 6-24 volts, D.C. If not, then start reading the schematics. Normally, this is a static exciter box problem. In the army, we would just change it and see what happens. About 98% of the time, that fixes it. Also a seldom seen culprit is the, (Speed Switch) S-9-1 contacts. They shut off the starter, and sends a signal to K-5 to energise the Exciter, which lights off the Main Generator. Good place to start.

 

[Old Man]

Ok, I checked for dc voltage at the 110 outlet like you said and there is none at all when holding up the start switch. I am not sure what the speed switch is? Is the schematic you are referring to on the generator or in a TM? Thanks for your help.

 

[Guyfang]

Yeah, the -12 manual has schematics and wire diagrams. Should be in the SS section for Generator manuals.

For generator mechanics, the control panel end of the generator set is the REAR of the set. So, if you look on the left side of the generator, open the front door. There is something that looks like beer can if it's an old speed switch, if its a new speed switch, it should be about 8-9 inches long, and be hooked to an adapter that is on the side of the engine block, It has a cannon plug hooked to it. It also has a small, wee, tiny little reset switch on it. The switch has a rubber cover. Push it in, then try to start the set again. The S-9-1 contacts are inside the speed switch. There are ways to test it, but you need someone to help, and you need to be able to use the schematics.

 

[Old Man]

Ok, now your talking a language I understand. I know a thing or two about beer cans. I believe I found the beer can ah....I mean speed switch you are referring two. The breaker on top did not appear to be tripped. I pushed it down anyway and started the generator but still nothing. Could you describe what the static exciter box looks like? What would you suggest I do next? Try to replace the exciter box , or do something more with the speed switch?

 

[Guyfang]

View attachment Dok1.docx

Hope this worked.

This is a drawing of the static exciter. Item 76 is the volt regulator. That is NORMALLY the problem. You need to download the manuals and start looking at troubleshooting, and the schematics. Unless you have another gen set to take parts off of, you are going to need to troubleshoot. Looking through the parts manual will also help you familiarize you whit the different components and what they are called.

 

[Old Man]

Ok, I did all that and have found out a few things. I jumped across pins A & C on the speed switch J37 plug and found I do have 24 volts across F1 & F2 coming out of the exciter box. According to the TM that indicates the problem is probably the speed switch. I did the continuity and discontinuity checks on the speed switch pins and those check out. Can the speed switch still be the problem even with them checking out? One other thing of note. When holding the start switch up I notice the voltmeter climbs to about 24 volts and then drops back when I let go of the switch. Is that the exciter voltage I am seeing? I checked again and I still have no dc exciter voltage at the 110v receptical.

 

[Guyfang]

Yep, the speed switch has to be functioning for you to see if the contacts really open/close. How did you check the continuity and discontinuity checks? If the speed switch does not let the exciter voltage, (the 24 volts you saw) through to the main AC, then it will not show up at the 110 volt outlet.

 

[Old Man]

I just took the cannon plug off the speed switch and used my vom on the speed switch pins and determined that I had continuity across pins a&b and g&h but no continuity across pins a&c, d&e or f&j. I took the speed switch apart and the three switches in there do not appear at least to be sticking. Am I correct that since I have exciter voltage I may as well go ahead and change out the speed switch?

 

[Guyfang]

OK,

A and B are your start circuit. When the engine hits a certain RPM, the speed switch opens one set of S-9-1 contacts, to lock out the starter. There is another set of contacts to the S-9-1 circuit, that close. energising the K5, (field Flash) relay. Then and only then can the exciter pass voltage through the speedswitch. The S-9-2 contacts are not used, the S-9-3 are the overspeed contacts. The checks you did are "static" tests. The only way to see if the contacts ope and close, is to have the speed switch hooked up, start the set and check for voltage at the K-5. See if K-5 energises, and if the contacts close allowing voltage to go to the excitor. It would be advisable to have someone to help you do this.

 

[Old Man]

Well the latest is that I bought a new speed switch and installed it, but the generator is still not producing power. Not only that but with the new speed switch the engine will not shut off. I had to disconnect the plug to the speed switch to kill the engine. Shouldn't a new speed switch be interchangeable with the older style? I have included a photo of the two switches side by side, Any ideas?

 

[Guyfang]

Can you give me the part numbers of the old and new speed switches? The NSN also, if you have it? Not all speed switches are the same.

 

[wanderingwillys]

Slightly different issue with my 005 - don't want to hijack this but if needed we can start a new thread - I can start and run just fine - holding the start switch will flash as designed and then I have Hz and V on the panel (and can adjust both with RPM and the Field Knob respectively) but I get nothing to the input of the main breaker (no power on either side or anywhere on the reconnection board) - the breaker seems to open and close normally and no alarm panel lights are lit.

I gather the generator is making power and the instruments pick it up somewhere very close to the winding but I am interrupted prior to the board...

Thoughts?

Matt

 

[Guyfang]

Wanderingwillys,

This is hard to believe. CT1, CT2 and CT3 measure voltage for your meters. So if your meters are reading right, the G-1, (main gen) has to be putting out voltage. The fact that the hertz meter is reading means A.C. is present. As the thermal watt converter uses an A.C. signal to convert it to D.C. for the hertz meter.

On TB-6, what you call the reconnection board, connections 1,2 and 3 should read A.C. voltage when measured against LO. There is nothing between the G-1 and the TB-6 to interrupt the flow of voltage. From TB-6 to the CB-2, (main output contactor) there is nothing to stop the flow of voltage from the TB, to the input terminals of CB2. So, mesure again. Did this gen set work right before? And maybe yes, if this is going to be a longer operation, you should start another thread. Its hard enough for me and the others to keep all this stuff straight. My brain is similar to swiss cheeze, only the holes are smaller in the cheeze.

 

[Old Man]

The old switch is a Sunchro-Start model Go-3Ma Part # SA-1644 and I think it is nsn 5930010219378 and I believe TM 5-6115-458-34 and TM-07536A-35, DoD drawing # 70-4058. I also found on the trouble shooting schematic on the generator... Speed Switch- S9-1 Start disconnect and field flash, S9-2 Governor On Off, S9-3 Overspeed.
On the new switch it is a REM PRODUCTS, SWITCH OVERSPEED nsn 5930-01-246-9266 P/N (80063) 70-1105-24. And then on another tag it says ELEMENT 1 Transfer 300 rpm P/N (80063), ELEMENT 2 Transfer 600 rpm 70-1105-24, ELEMENT 3 TRANSFER 1225 rpm LATCH

 

[Guyfang]

The old switch is a Sunchro-Start model Go-3Ma Part # SA-1644 and I think it is nsn 5930010219378

The NSN 5930-01-021-9378 is listed in the TM-9-6115-465-24P, as a speed switch for the MEP-114A, (a 400 hertz, Precise Power Gen set) and so it can NOT be used on a MEP-005A.

and I believe TM 5-6115-458-34 and TM-07536A-35, DoD drawing # 70-4058. I also found on the trouble shooting schematic on the generator... Speed Switch- S9-1 Start disconnect and field flash, S9-2 Governor On Off, S9-3 Overspeed.
TM-5-6115-548-34. What has this manual to do with a MEP-005A?
Yes, the S9-1 is to disconnect the starter when the speed switch senses that the engine speed is high enough, and flashes the fields at the same time. On the MEP-005A, the S9-2 contacts are not used, as it is a utility gen set, not a precise gen set. S9-3 is to shut down the gen set when it over speeds.

On the new switch it is a REM PRODUCTS, SWITCH OVERSPEED nsn 5930-01-246-9266 P/N (80063) 70-1105-24. And then on another tag it says ELEMENT 1 Transfer 300 rpm P/N (80063), ELEMENT 2 Transfer 600 rpm 70-1105-24, ELEMENT 3 TRANSFER 1225 rpm LATCH

The NSN 5930-01-246-9266 is the proper NSN to fit the MEP-005A. The part number 70-1105-24 is not listed in the parts manual. Are the NSN and the part number both listed on the switch?

The only NSN that is interchangeable with 5930-01-246-9266 I know of, is NSN: 5930-01-023-4343

I would give my left nut to have a copy of FEDLOG. You need to get the right books, for the right gen set. Also important is UOC. That is Useable On Code. Whenever a part has a UOC list next to it in a parts manual, bells and lights should go off in your head. That means some parts will NOT fit every type of equipment listed in the parts manual. When you look at the cover of a TM, it lists all models covered in the manual. When you look up parts, look at the number of models, then turn to the Section 1, Introduction of the parts manual. Toward the end of the section, the UOC will be explained, and the proper code is listed next to the proper model and NSN from that model. That code will be listed next to the repair part you need. A good example is the MEP-005A. In the parts manual, are three different models listed. In the parts listing/table of contents, are two different listings for speed switches. One mechanical, one electric. Look at the first speed switch, and it shows TWO different NSN's. AND, a UOC listed next to both parts. Look at the next speed switch in the parts manual, and you will find ANOTHER TWO different NSN's listed. UOC listed next to them. That's 4 different NSN's, for one part. The UOC tells you what model the switches fit.

If the new switch is marked with 5930-01-246-9266, it is indeed the right switch. Do you know its good? Just because it looks new and shiny is not a sure sign its good. I have more times then I can count, ordered a part, unwrapped it, installed it and it was bad.

The top switch in your picture is a mechanical switch, the bottom one an electronic switch. The part number 70 1105-24 is not listed in the TM, for the MEP-005A. Like I said, my kingdom for a FEDLOG. FEDLOG lists any and all interchangeable parts. Will the seller of the part vouch for its serviceability?

 

[Old Man]

Yes, the new switch has that number. I have attached a few more photos. The vendor has agreed to let me return the switch. So whether it is the wrong switch or defective I may as well do that and start looking for another switch.

 

[wanderingwillys]

I will start up a new thread ( http://www.steelsoldiers.com/showth...he-Main-Circuit-Breaker&p=1874832#post1874832 ) - this production of power and the Hz reading had me confused as to the issue as well - I have never had the machine output power but I am also just now testing it for the first time since acquiring it

Regards

Matt

 

[Old Man]

Update. Well I went and bought another speed switch. This one is the exact same model right down to the same serial #, which I thought was odd. It's a used switch but looks almost new. I know that doesn't necessarily mean anything but its not only clean but still pretty shinny. Doesn't look like it could have tons of hours on it. But anyway, still nothing, no power. So we have determined we have exciter voltage out of the static exciter box, even shows on the voltage meter when holding up on the start switch. Have replaced the speed switch, and still nothing. What the heck else could it be? Can the static exciter box produce 24 volts and still be bad somehow? Or is that all it does?

 

[Guyfang]

So we have determined we have exciter voltage out of the static exciter box, even shows on the voltage meter when holding up on the start switch.
What plug, what pins for output of exciter? What voltage shows on the meter, 24 volts? Or something else.

Can the static exciter box produce 24 volts and still be bad somehow? Or is that all it does?
The static exciter should send voltage to F-1 and F-2 to light off the main gen. F-1 and F-2 wires should be the only small wires that go into the main gen. They should also be marked with a metal tag, F-1 and F-2. They should go to a TB, and I am not at home, so I can not look it up. But it should not be too hard to trace them, or read the schematics. And do not forget that K-5 on the A-5 circuit card has to be working right. The static exciter contains the volt regulator as well as the excitor.