MEP-006A Issues

[cbrTodd]

I do some volunteer work with a Christian camp near where I live, and they have asked me to assist with getting their backup generator operational. It is an MEP-006A unit, obtained through a FEMA grant. They had it installed a few years ago and the power company connected it by a manual transfer switch to their utility service. I know almost nothing about it other than what I have been able to find in TM 5-6115-545-12. The hour meter shows 57 hours and from looking at the condition of the engine and the wiring inside, it does indeed look to be a very low hour unit.

When I first inspected it, it had dead batteries so I could not start it. After replacing the batteries, it starts great and stays running if you hold it in 'start' position until it has oil pressure like the TM says, but shows nothing on any of the AC gauges. This seems not to match with step 3 of figure 2-7 of the starting instructions. I can get it to show a frequency / voltage / % load on the gauges by holding the start switch back in the 'run' position, but when I let off it goes back to no load and the AC gauges all go to zero. I can move the circuit breaker switch to either the open or closed position and it doesn't make a difference. The circuit breaker closed light only illuminated when I held the start switch on and then pushed the switch to the closed position. I couldn't find this symptom in the troubleshooting tree, which leads me to believe I am missing something simple. Anyone know what I should check next?

 

[cbrTodd]

Ok folks, I spent some time troubleshooting this MEP-006A yesterday, and I'm still stuck and in need of guidance.

It starts instantly and will generate power as long as I hold the switch in the 'start' position, but if I set the switch to 'run' all of the AC gauges go dead and the engine continues to run without generating AC power. I have been following the troubleshooting steps for 'Main generator fails to flash' but I'm not sure if that is even right since it will flash with the switch held at start. The speed switch functions correctly based on the continuity checks, and the K5 DC relay checks out properly and has continuity when 24V is applied across the specified terminals. It continues to charge the batteries and show oil pressure, fuel level, etc. in the 'run' position.

It is worth noting that the electrician who initially hooked it up had the main lugs hooked up incorrectly and had lowered the speed such that it was producing 120 volts across the L1-L2 leg (which should have been at 208 volts) and the frequency was way low. I don't know how long it would have run like that, but from the first time I worked on it, the generator has never produced AC power without holding the switch to 'start'. The connection board that selects 120 / 208 volts has been set correctly all along. Could this have messed something up, and if so, what?

Summer is near so their busy season is close and they are about to go another year with an unreliable power company and no backup generator if I can't get it fixed.

 

[Guyfang]

Ok folks, I spent some time troubleshooting this MEP-006A yesterday, and I'm still stuck and in need of guidance.

It starts instantly and will generate power as long as I hold the switch in the 'start' position, This is as it should be but if I set the switch to 'run' all of the AC gauges go dead This is because your volt regulator does not take over the function of keeping the G1, (main generator) excited and the engine continues to run without generating AC power. I have been following the troubleshooting steps for 'Main generator fails to flash' The set flashes, so that's not it but I'm not sure if that is even right since it will flash with the switch held at start. The speed switch functions correctly based on the continuity checks, and the K5 DC relay checks out properly and has continuity when 24V is applied across the specified terminals. It continues to charge the batteries and show oil pressure, fuel level, etc. in the 'run' position. The speed switch and K5 have nothing to do with this problem.

It is worth noting that the electrician who initially hooked it up had the main lugs hooked up incorrectly and had lowered the speed such that it was producing 120 volts This is where everything went bad across the L1-L2 leg (which should have been at 208 volts) and the frequency was way low. I don't know how long it would have run like that, but from the first time I worked on it, the generator has never produced AC power without holding the switch to 'start'. The connection board that selects 120 / 208 volts has been set correctly all along. Could this have messed something up, and if so, what?

Summer is near so their busy season is close and they are about to go another year with an unreliable power company and no backup generator if I can't get it fixed.

When you run a gen set way below the rated speed, it burns up the volt regulator.

There are several ways to fix this problem.

1. Buy a volt regulator. NSN: 6110-00-030-7815. There are three in the big auction site.

2. Buy a volt regulator card. NSN: 6110-00-342-9762

3. Fix the volt regulator card. Find a smart rocket scientist to fix it. Its not hard. The test and repair procedure is in the -34 manual. When looking up parts, go to figure 59, of TM 9-6115-545-24P. Figure 60 shows also the repair parts for an card, but its for the 400 hertz card, and you cant use that.

4. Buy an exciter assembly. The volt regulator is in the exciter assembly. NSN: 6115-00-244-1214. There is one in the big auction site .

How would I do this? Inspect the exciter assembly to see if any thing else is damaged. If not, I would get a volt reg, install it and that should do it. Keep in mind, other things could be damaged in the exciter. I can't promise you anything. But 99.9% of the time, its just the card.

 

[cbrTodd]

Thank you, Guyfang! This is very helpful information for me. I thought I had read that running a generator at idle would damage something, but I didn't know what it would damage and what speed / duration would cause it.

I looked at the internals of the exciter assembly yesterday and didn't see anything that looked burned or melted so I'm going to take a gamble on getting a voltage regulator and see if that will fix it. The test equipment in the -34 is beyond what I have, so option 1 seemed like the best bet for me. I really appreciate you taking time to help me out! I'll make sure that everyone out there knows not to touch the throttle knob in future, too!

 

[Guyfang]

That's the thing with the throttle. Most folks, if they grow up in a non city area, learn to idle equipment after starting, to help get the engine oil up to pressure in the engine. So this happens a lot. Your "electrician" who reduced the RPM, should be drawn and quartered. Always set the throttle and leave it there. Always. If you need to bump it up a tad, fine. Under a good load, it will fall a few hertz. Sometimes the back side of the volt reg card will show a burn spot. Take care and be safe!!

 

[LittleBill]

guyfang,

can you explain to me how the voltage regulator works in start but not in run? if it was burned out, he would not have correct voltage? what am i missing here?

 

[Guyfang]

OK, I don't have manuals here, but will try and give you the short version.

when you turn S2 to the start position, several things happen.
1. Starter engages.
2. The S9 switch, (Overspeed Switch) monitors how fast, (RPM) the engine is turning the G1, (main Gen).
3. At a certain RPM, the S9 Sences that the RPM is high enough, and S9-1 contacts reverse, turning off the starter, and sending 24 volts to the Excitor, to light off the G1, and the main gen produces power.
4. When the S2 is released, the Excitor kicks out, and the volt regular takes over the function of keeping the G1 producing power.

The Excitor circuit is compleatly separate from the volt regulator circuit. Both are in the Excitor box, as they do work hand in hand, but it's the volt regs job to monitor the voltage, and react to inputs to raise or lower the voltage. We had massive problems with this system in the mid 70's. Were issued 12 of thes sets, (MEP-115A) and within 60 days ove 50% were deadlined for the Excitor system. Things got better after that, but the Excitor box was always a problem.

So so to give you the short answer, the volt regulater does not work in the S1 start position. Only after the S1 is released, and the Excitor has lit the G1 off.

Is is that good enough?

 

[LittleBill]

OK, I don't have manuals here, but will try and give you the short version.

when you turn S2 to the start position, several things happen.
1. Starter engages.
2. The S9 switch, (Overspeed Switch) monitors how fast, (RPM) the engine is turning the G1, (main Gen).
3. At a certain RPM, the S9 Sences that the RPM is high enough, and S9-1 contacts reverse, turning off the starter, and sending 24 volts to the Excitor, to light off the G1, and the main gen produces power.
4. When the S2 is released, the Excitor kicks out, and the volt regular takes over the function of keeping the G1 producing power.

The Excitor circuit is compleatly separate from the volt regulator circuit. Both are in the Excitor box, as they do work hand in hand, but it's the volt regs job to monitor the voltage, and react to inputs to raise or lower the voltage. We had massive problems with this system in the mid 70's. Were issued 12 of thes sets, (MEP-115A) and within 60 days ove 50% were deadlined for the Excitor system. Things got better after that, but the Excitor box was always a problem.

So so to give you the short answer, the volt regulater does not work in the S1 start position. Only after the S1 is released, and the Excitor has lit the G1 off.

Is is that good enough?

its a great answer.

last question, like you said the regulator adjusts the voltage, so how did the op adjust the voltage (too low) while in start? apparently the excitor regulates as well to some degree?

 

[Guyfang]

its a great answer.

last question, like you said the regulator adjusts the voltage, so how did the op adjust the voltage (too low) while in start? apparently the excitor regulates as well to some degree?

It is worth noting that the electrician who initially hooked it up had the main lugs hooked up incorrectly and had lowered the speed such that it was producing 120 volts across the L1-L2 leg (which should have been at 208 volts) and the frequency was way low. I don't know how long it would have run like that, but from the first time I worked on it, the generator has never produced AC power without holding the switch to 'start'. The connection board that selects 120 / 208 volts has been set correctly all along. Could this have messed something up, and if so, what?



The exciter does not regulate. It simply applys 24 volts to the F1 and F2 wires on the G1. It "kick starts" the G1 into making voltage, nothing more. The electrician simply turned down the hertz, (engine speed) to reduce the voltage. He probably didn't do it in the start position, (I hope). I assume he did it because he did not read the -12 manual to find out how to get a lower voltage, (120 volt) when he saw 208 volts on the meter. But assuming can get me in trouble every time, so he may have had the throttle pushed in, and was trying to adjust the volts higher/lower, and also another common screw up is some people think/try to adjust the frequency with the knob on the control panel. Sadly, to many people try and fool with a machine, without getting smart about it. That knob only works with a Class 1 set. Precise power sets. And a MEP-006A is not a precise set. In any case, running a gen set at less then rated speed is a killer.

 

[cbrTodd]

I got a chance to work on this generator after work today, but unfortunately I don't have any good news to report. I replaced the voltage regulator and it's still doing the same things it did before. When I let off the start switch, it no longer makes power.

I brought the old voltage regulator home with me and took the card loose from the assembly and I can't see anything in it that looks visibly burned. The shellac behind the T202 component on the board is clear where the rest of it is yellow, but that's all I saw that indicated that anything potentially got hot on it. Does this change anything, or should I tell them to bite the bullet and buy the exciter assembly? Is there a set of contacts on the S2 switch that I should check out first, that it could just not be sending power to the exciter assembly? If there's a relevant section of the TM 5-6115-545-34 TM that you can point me to for troubleshooting this issue rather than continuing to bug you, I'd appreciate the help!

 

[Guyfang]

When you release the S2, and the voltage drops off, are there and idiot lights that come on?

 

[cbrTodd]

When you release the S2, and the voltage drops off, are there and idiot lights that come on?

When I release S2 to go back to the 'run' position, no idiot lights / warning lights come on. I have verified using the test / reset switch that all the bulbs do indeed work.

 

[Guyfang]

Go to the A5 card in the control panel. Look at the front and back, for burn marks. Pull off the K5 relay, (exciter relay) and test it. Below is a quick drawing I made to show you the relay and pins. Pins 3 & 6 are the coil. first test the coil, to see if it is good. Then test the normally closed contacts, pins 2 & 4 and pins 5 & 7. You should have continuity. Then test the normally open contacts, 1 & 5 and 2 & 8. They should show no continuity. Then apply 24 volts to pins 3 & 6, (the coil). Re test all the fore mentioned contacts. They should have reversed. if the card is burned, it needs to be repaired or replaced. If the relay is not in order, replace it.

View attachment Scan_0002.pdf

 

[cbrTodd]

Is this the same test in the -34 described on table 2-2 item 22? It references the K5 relay on the A5 card, and has you test at the terminals on the card rather than the pins on the relay itself. I did that test a couple weeks ago and it all checked out OK. I can go back and check the other pairs of pins if needed though. I did not see any signs of damage on the A5 card. The TM only specified to check continuity between 1-14 and 2-15 though, and those pairs were both open with no voltage applied across card terminals 13-15, and closed with 24v across 13-15. I didn't go further in that step after that.



Thank you again for helping me out with this!

 

[Guyfang]

Now that I have mail back, check the wiring; Perhaps the wire numbers on the S9 to the correct pins, and the plug connected to the right locations. The Regulator is not picking up AC output and sending the static exciter the voltage to provide a field. It reminds me of a bad voltage adjust rheostat. This comes from the Regulator. I am being a bit skimpy here, I am not at home, and using a note pad to write. Its a PITA. I hate using a note pad. Somehow, the AC signal is not getting back to the regulator, after excitation, to keep the field excited. When I can get to my schematics, I will take another look.

 

[cbrTodd]

I only get down to this camp a few times a year, but a couple weeks ago in anticipation of my trip today I told the camp leader that the entire exciter module was available online and that it was my only remaining suggestion to fix the generator. Tonight I swapped out the exciter module, and thankfully it fixed the issue. The set operated exactly as expected and remained solid at 60 Hz.

Now I just have to figure out how to get them an affordable load bank solution to exercise it periodically to prevent it from wet stacking. They didn't have too many appliances operating this evening, but the highest I ever saw on the load meter was 20%. Next time I'm there I'll try turning on all the AC units and the resistance load appliances and see how high it goes. They may not have needed a 60 kW generator, but it's what they have, so now I have to find a way to keep it working for them.

Thanks again for the help guyfang!

 

[Guyfang]

I only get down to this camp a few times a year, but a couple weeks ago in anticipation of my trip today I told the camp leader that the entire exciter module was available online and that it was my only remaining suggestion to fix the generator. Tonight I swapped out the exciter module, and thankfully it fixed the issue. The set operated exactly as expected and remained solid at 60 Hz.

Now I just have to figure out how to get them an affordable load bank solution to exercise it periodically to prevent it from wet stacking. They didn't have too many appliances operating this evening, but the highest I ever saw on the load meter was 20%. Next time I'm there I'll try turning on all the AC units and the resistance load appliances and see how high it goes. They may not have needed a 60 kW generator, but it's what they have, so now I have to find a way to keep it working for them.

Thanks again for the help guyfang!

Glad to hear you are up and running. There are several threads here in SS that cover making load banks. Most are very informative. You can use junk yards or scrap yards to get lots of what you need. Heating elements. Read the threads, and then give it some thought. The guys here will help you out!

 

[mcii]

Find your HVAC contractor whjo keeps some old units around till he piles up enuff to make a scrap/recycle run see if he has any ELECTRIC heat units and pull the heating elements out or better just find the entire inside unit and leave the heating elements alone and mounted as they are, add several more heat strips in the air flow stream till or as much as you can fit.. fuse them and give it a try. you didn't tell us if this is wired up for single or 3 phase as it is an 006 it will have the ability to produce 1 phase the later 806 models will not make single phase or does the camp already have 3 phase capability and no 1phase mod effort is needed..Im taking you to review what type of load to try and find or build to help actual loadbank testing ability. You shared w us the link board was set for 120/208 so don't get funny and try and make the set produce 240 till we are sure you are set for that capability, and from the sound of it you are not.. but rather 3 phase, you have bitten off a lot to chew here and have made good progress, just a little more to go and then you can drop into just regular PM of the set and surrounding conditions. good luck keep us informed, help abounds here within SS ..
best.. mac/mc

 

[ajallow80]

When you run a gen set way below the rated speed, it burns up the volt regulator.

There are several ways to fix this problem.

1. Buy a volt regulator. NSN: 6110-00-030-7815. There are three in the big auction site.

2. Buy a volt regulator card. NSN: 6110-00-342-9762

3. Fix the volt regulator card. Find a smart rocket scientist to fix it. Its not hard. The test and repair procedure is in the -34 manual. When looking up parts, go to figure 59, of TM 9-6115-545-24P. Figure 60 shows also the repair parts for an card, but its for the 400 hertz card, and you cant use that.

4. Buy an exciter assembly. The volt regulator is in the exciter assembly. NSN: 6115-00-244-1214. There is one in the big auction site .

How would I do this? Inspect the exciter assembly to see if any thing else is damaged. If not, I would get a volt reg, install it and that should do it. Keep in mind, other things could be damaged in the exciter. I can't promise you anything. But 99.9% of the time, its just the card.

I need a voltage regulator for my MEP006a too. You mentioned there is one available on the BIG AUCTION SITE?

 

[Guyfang]

Was a while back. Also an excitation card and the regulator. But its been a few weeks. Plug in the Part #'s and NSN's.