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Thread: wildly fluctuating voltage on my mep 002

  1. #1
    Sergeant
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    Default wildly fluctuating voltage on my mep 002

    I had it switched to single phase. I turned it off and switched to three phase then restarted it. As soon as it started the ac voltage was fluctuating between 160 and 260 volts ac. I turned it off and switched it back to single phase but the voltage still fluctuates Any idea as to what might be causing this problem? Thanks in advance for any insight

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    Probably going to need a bit more information...after you reconfigured it to 3 phase and 1 phase did you place any loads on it? What is this generator normally used for...home backup or? What loads were placed on it when it was last running correctly?

    Normally going to high voltage is due to a failure in the AC voltage regulation circuit (AC Regulator board, Transformers, etc.). Switching it to 3 phase and back to 1 phase shouldn't hurt it if unit is off which you said it was.
    GEN #1 House Gen PU-751/M: 1986 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #2 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #3 Shop/Barn Gen NF-2 Enclosure: 19XX MEP-002a w/Aux Tank
    GEN #4 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 (a work in process)

    * Disclaimer - My comments on this forum are based on my opinion and my experiences only. It is your responsibility to verify any information before using or to hire a professional.

  3. #3
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    Quote Originally Posted by Chainbreaker View Post
    Probably going to need a bit more information...after you reconfigured it to 3 phase and 1 phase did you place any loads on it? What is this generator normally used for...home backup or? What loads were placed on it when it was last running correctly?

    Normally going to high voltage is due to a failure in the AC voltage regulation circuit (AC Regulator board, Transformers, etc.). Switching it to 3 phase and back to 1 phase shouldn't hurt it if unit is off which you said it was.
    I didnít reconfigure it. The mep 002 has a switch to go from single to three phase. I turned it off when I switched it from
    Single to three phase. When I turned it back on it was fluctuating wildy. I use it to power a small hotel in an island near Cartagena Colombia. It runs 24/7/365. I have several. Trying to repair this ASAP as itís my back up to the other two.

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    Yeah, I know its a rotation of the "AC Output Reconnection Switch"...I have 3 MEP-002a's if you look at my signature. Have you downloaded all the MEP-002a manuals and followed the troubleshooting guide?

    The contacts on that switch are known to become intermittent with age. I would switch it back and forth several times to exercise the contacts on the wafers between the switch contacts since this happened after switching it.

    There are several threads that if you search "MEP-002a MEP-003a voltage high VR" or similar terms...you will get several hits for threads where this has happened. Causes range from the switch itself, the 2 rectangular potentiometers on the AC Voltage Regulation Board, the VR board itself (output transistors) transformers, grounding, etc.

    Since you have multiple MEP-002a units, if you are in a position to take one down and swap out known good parts it might help expedite your troubleshooting process. Swapping out the AC VR is easy and would eliminate that as a problem, but I would follow the TM trouble shooting guide order first.

    Edit: Here is a good thread that is describing similar problems to what you are experiencing and the troubleshooting that was performed.
    Last edited by Chainbreaker; 08-12-2019 at 22:47.
    GEN #1 House Gen PU-751/M: 1986 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #2 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #3 Shop/Barn Gen NF-2 Enclosure: 19XX MEP-002a w/Aux Tank
    GEN #4 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 (a work in process)

    * Disclaimer - My comments on this forum are based on my opinion and my experiences only. It is your responsibility to verify any information before using or to hire a professional.

  5. The Following User Says Thank You to Chainbreaker For This Useful Post:

    Zed254 (08-12-2019)

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