MEP-803A Low voltage output.

[ksmity]

Hello everyone, I am new to this community and am grateful to have this forum for help. My newly acquired genset has 289 hours on the hour meter and the engine seems to run well. I have changed all the fluids and filters. I have downloaded the manuals and have tried to follow them the best I can. The genset does have a 3 amp fuse on the voltage regulator but does not have a MOV installed, one is on order. I have a few questions:

1- The AC volt meter and AC ammeter do not work on every AM-VM setting. When the AM-VM is set to 3 phase power, the volt meter seems to work. I traced the wires using the wire schematic and replaced the AM-VM switch without any change.

2- In single phase power my DMM shows an output voltage of 177-210 at the output lugs. I have taken measurements at the voltage regulator using the testing procedure (2-27.2) and are as follows:
120/240: voltage range is 177-210
step h: 7.5 VDC
step j: 87.5 VAC
step l: 119.6 VAC
step n: 4550 ohms

When doing Quad Circuit testing:
Terminal 1 and 2: 1.2 VAC
Terminal 3 and 4: 102.2 VAC
Terminal 5 and 6: 4.2 DC
Terminal 7 and 8: 74.6 VAC

I purchased this generator because I thought I could use the manuals to make any repairs that it needed but I am over my head and any help would be greatly appreciated. I have contacted 3 different diesel generator repair shops in my area without any response. Does this genset sound repairable?

Thank you

 

[Ray70]

Welcome to the forum. ANYTHING can be repaired. The guys here should be able to walk you through it.
The first thing I would do it exercise both the AM/VM and AC select switches ( with the machine off )
Cleaning the switches with contact cleaner as well would be recommended.
Then retest. Also, please tell us what you get for voltage on 3 phase settings as well as what is on L3 -L0 when is 120V mode.
Lastly, does it seem like you get any voltage change when using the voltage adjust knob, or does it seem inactive?

 

[Farmitall]

Tag for later reply

 

[Farmitall]

Tag for later reply.

 

[Lovetofix]

Make sure that the Voltage select dial and AM/VM dial are set to match. Do not move them with the genset running!


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[ksmity]

Welcome to the forum. ANYTHING can be repaired. The guys here should be able to walk you through it.
The first thing I would do it exercise both the AM/VM and AC select switches ( with the machine off )
Cleaning the switches with contact cleaner as well would be recommended.
Then retest. Also, please tell us what you get for voltage on 3 phase settings as well as what is on L3 -L0 when is 120V mode.
Lastly, does it seem like you get any voltage change when using the voltage adjust knob, or does it seem inactive?

Thank you for you suggestions. How do I measure voltage of L3-L0? is L0 the N lug? I will check 3 phase voltage output in the morning. The voltage adjustment knob does work, I measure from 177 and 210 VAC at the output lugs.

 

[mciikurzroot]

Several things to check, as well remember. When the INTERIOR voltage selector switch is say the 120/208 position, what does your PANEL voltage meter show V. the measured voltage on the load terminals, be sure your contactor is closed you should near identical voltage between L0 and L1 L2 or L3 you should be reading 120 or very close maybe 110-130. likewise voltages between any combination of L1 2 or 3 should be near identical. then go and select 120/240 voltage .. NEVER ever NEVER move this selector switch while the set is operating, the front panel selector voltage amp reading switches you can move between positions at will. BUT NEVER THE INTERIOR SELECTOR SWITCH. Yon should readapt or near 120 between L0and L1 or L3 no voltage should be reading between L0 and L2, between L1 and L3 you should be reading at or near 240 .. if not in both these test but you are reading near identical voltages between the points you are testing .. on the actual voltage regulator their is a 'voltage range' adjustment pot via a hole in the front of the voltage regulator between terminal 4-5.. with the FRONT panel voltage adjust knob in the mid ranger of its 270 degree spread, set it in the middle position and then the same for the pot inside the regulator, all should be well and not pot at its extream position, this whole sequence gets screwed up when some dipshit is sure he is right that he can get 240 volts out when the setting is in the 120/208 position, but im getting away from the message intent, if indeed this solves your voltage issues, let us know.
best: mac/mc

 

[Guyfang]

Make sure that the Voltage select dial and AM/VM dial are set to match. Do not move them with the genset running!


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Weeeeeel. You can and most assuredly should, use S6, when the set is running. Its S8, that needs to be only changed when running.

 

[ksmity]

Thank you to every one who took time out of their day and help me with their advise but I am embarrassed to say that I am an idiot. The plastic knob on the voltage reconnection switch was stripped. When I turned the knob, nothing was happening, it stayed in 120/208v 3 phase. That's why the AC Volt gauge would not read anything when I thought I was putting it in 120/240v single phase. I can not believe how many hours I have wasted trying to figure out what was wrong and it turned out to be stripped out knob.

Thank you again for the help.

 

[Guyfang]

Thank you to every one who took time out of their day and help me with their advise but I am embarrassed to say that I am an idiot. The plastic knob on the voltage reconnection switch was stripped. When I turned the knob, nothing was happening, it stayed in 120/208v 3 phase. That's why the AC Volt gauge would not read anything when I thought I was putting it in 120/240v single phase. I can not believe how many hours I have wasted trying to figure out what was wrong and it turned out to be stripped out knob.

Thank you again for the help.

Whenever some one tells you he is an "Expert", what he is really saying is, "I have screwed up so many things during my life time, and each and every one of them has taught me something". Been there, done that.