Motor generator exciter not making voltage, help please
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  1. #1
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    Default Motor generator exciter not making voltage, help please

    EE13421, Was working last Saturday, machinist came in to run it Tuesday, and it won't start spindle. Motor generator starts, exciter only puts out 12 V. (E1- E2)

    Resistance E 1 / E2 = 26 Ohm
    E1 / gen E2 = 610
    Insulation check as no reading, OL on my Fluke 75
    Shunt resistor slider to far end is @ 210 Ohm
    Generator E2 to exciter E3 is also 210 Ohm

    I tried the battery jump with a new 9 v battery and diode. I could only get 40 V max.

    I tried flashing the exciter. Push button and 2 amp fuse between E1 ans E2
    The fuse blows immediately with a nice bright flash and E! and E2 only show 12.4 v. I did this three times with no improvement.

    E2, generator to E3 exciter @ 210 Ohm, as is the E2 to slider

    We previously had a problem with the anti plugging coil and points not releasing. This was the first thing we checked. The points looked clean and they are closed with the power off.

    I dont know of any more info or checks . Can anyone make sense of what I've checked and offer suggestions on what next? Take the exciter to a motor shop?

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    Quote Originally Posted by J Henricksen View Post
    I dont know of any more info or checks
    If only to sorta round things out, you could also tell us it has a nice looking commutator, good brushes, well-seated, not worn beyond use, and not dirty and hung up.

    Bill

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    Yes that is the case. This is a food packaging machine manufacturer and custom packaging place. I can lay on the floor there and not get covered in chips. They are quite meticulous with cleaning. This machine isn't used in production, just to modify parts that have been made by other job shops. Maybe gets 3 hours a week run time.

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    Quote Originally Posted by J Henricksen View Post
    Yes that is the case. This is a food packaging machine manufacturer and custom packaging place. I can lay on the floor there and not get covered in chips. They are quite meticulous with cleaning. This machine isn't used in production, just to modify parts that have been made by other job shops. Maybe gets 3 hours a week run time.
    As-original MG's have not been my 'thing' what with Solid State conversion.

    Experts should be along shortly, though.

    If all-else fails, I am still tripping-over a working-when-removed 1942 round-dial piggyback-exciter MG that should fit your machine. Ohmites as well. Motor control switch I may have SOME parts of. The DC control panel was sent-off to a new home long since.

    Bill

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    Quote Originally Posted by Monarchist View Post
    As-original MG's have not been my 'thing' what with Solid State conversion.

    Experts should be along shortly, though.

    If all-else fails, I am still tripping-over a working-when-removed 1942 round-dial piggyback-exciter MG that should fit your machine. Ohmites as well. Motor control switch I may have SOME parts of. The DC control panel was sent-off to a new home long since.

    Bill
    PS: Folks may be better able to assist if you could flesh out details of how you power it, what meters & c. you have available, any other prior fault history besides the sticky relay already mentioned.

    It appears you do have the manual & schematics and know how to read them.

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    The shop is powered by good heavy 480 v 3 phase. Guessing I would say 400 amp with 208/240/120 and 480/240traansformers and separate load boxes. They run about 8 custom contract packaging lines, baby food, single serve taco dip for schools etc. All of the checks i have made are in response to the searching and advice of this forum, searching for motor exciter issues.
    (2) Fluke 75 meters.

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    Quote Originally Posted by J Henricksen View Post
    All of the checks i have made are in response to the searching and advice of this forum, searching for motor exciter issues.
    Not aware of anything not covered several times. Not all of it is in threads as easily identified as that search, though. Lots more is buried as side-trips to other issues having to do with the Motor switch, other relays, power to contactors, etc.

    The 'sudden death' after a period unattended would have me looking for collateral damage from cleanup/washdown by staff, rodent or insect intrusion, switch and relay contact condition and functionality affected by heat & humidity if the facility was down over a weekend.

    Wires or their terminations CAN fail. There was one broken-off and still 'hovering' right over its contact on the back of my OEM DC Control box. Kept in place by years of build-up in the cambric fabric sleeve over it. Not detected until the braking resistors were pulled.

    The 'exciter' is, IIRC, compensated/balanced/tuned to be part of the MG 10EE's load regulation system, as to field power it produces, ergo worth retaining.

    If you have deadlines to meet, it will RUN without it, substituting any reasonably clean DC supply with enough current delivery to haul the field loads and contactor/relay actuator coil demands.

    Control transformer & ~ $3.00 packaged full-wave bridge rectifier the simplest of those, small DC motor Drive (I use Eurotherm/Parker SSD-507's) more flexible as to configuration, limit settings, & c.

    Only a few wires to move if you want to test that to see if the problem really IS the exciter itself.

    Good hunting!



    Bill

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    A 100 VA 240/120 transformer and a full wave bridge? Maybe a fuse for grins? feeding E1 and E2? We need to get some parts modified, maybe an hour run over the course of a day.

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    Quote Originally Posted by J Henricksen View Post
    A 100 VA 240/120 transformer and a full wave bridge? Maybe a fuse for grins? feeding E1 and E2? We need to get some parts modified, maybe an hour run over the course of a day.
    Not sure that is a heavy enough transformer. Double check that on PM.

    Regardless, DO keep in mind it is a 'band aid' and fix it proper once past the tight spot.

    The humble exciter feeds the control and logic circuits or 'brains' of a 10EE.

    - stable DC source to feed switches and relays so they may control other relays or contactors, then also the heavier actuators OF the contactors

    - variable DC, directly through a rheostat to the field circuit of the final-drive motor ~ 1.4 Amps.

    - Variable DC through another rheostat to INdirectly control heavier amperage Armature power by varying strength of the field of the primary DC generator that feeds it. 'Leverage' characteristic of the Ward-leonard concept.

    I've not measured it, but the Ohmite for control of that is the same power rating, and the generator sized to haul the final-drive motor, so should be MORE than 1.4 A, but not a great deal more.

    - and a small bite for its own field as well, of course.


    Bill

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    i may have a .5 kva transformer and some 30 amp bridges. Should I remove the belt driving the exciter if I try this ?

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    Quote Originally Posted by J Henricksen View Post
    i may have a .5 kva transformer and some 30 amp bridges. Should I remove the belt driving the exciter if I try this ?
    I would do so. Parasitic drag and unpredictable residual energy, wires-OFF ...etc.

    My luck, I'd bump something believed 'dead' and get meself rectumfried.

    Besides... once it is clear out of the circuit both electrically and mechanically, you can apply test leads, a bit more field than a 9 V (!) battery, spin it up with a hand power tool or vee-belted motor and see if it works at all.

    If not, much easier for me to freight you the exciter than the whole shebang.

    Even on the MG I am leaving AS an MG, that part, and the DC Control panel functionality as well will go over to Solid State so I can sneak a tacho feedback and more 'active' load regulation into its sandbox.

    Reliance did 'half' of that themselves on one of the 10EE variants. Dirty beach sand and tacho generator[1] ALTERNATIVES to support the other 'half' have gotten waaay cheaper since.

    Bill

    [1] Costly buggers, large and bulky. Over a thousand $USD for decent pure-analog ones with decent accuracy, linearity, immunity to temp swings and adjacent nasty electromagnetic fields.

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    12.0" machines and accessories made after Monarch finally adopted the industry standard for 10 + 2.5" = 12.5" are not that rare. Unusual, but not that rare.

    The same is true of M-G machines made after adoption of the WiaD.

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    Quote Originally Posted by peterh5322 View Post
    12.0" machines and accessories made after Monarch finally adopted the industry standard for 10 + 2.5" = 12.5" are not that rare. Unusual, but not that rare.

    The same is true of M-G machines made after adoption of the WiaD.
    ? Seniour Moments are a shared birthright by now, but just so the youngsters are not confused, I think that was meant to reply to a different thread we've been in recently?


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    I thought it might be his way of subtley telling me to find a donor machine.
    I'll put together a full wave bridge and control transformer and see if I can make it work. If so, I'll pull the exciter and take it to a motor shop that I know can figure it out.

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    Quote Originally Posted by J Henricksen View Post
    I thought it might be his way of subtley telling me to find a donor machine.
    I'll put together a full wave bridge and control transformer and see if I can make it work. If so, I'll pull the exciter and take it to a motor shop that I know can figure it out.
    Just about any motor shop can sort the exciter. Main MG is also straightforward, just two simple machines complicated mostly by sharing a common shaft.

    Winding interleave and 'interpole' arrangement of the four-brush final-drive DC motor is far less common, wants a shop with broader experience, DC hoisting and elevator motors.

    OTOH, the large-frame 3 HP Reliance very rarely set a foot wrong even 75 years out of the factory and counting.

    Over-built to begin with, and then a 10EE runs them significantly 'under stressed', even per their conservative nameplate.

    Bill

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    I have a rebuilt piggyback excitor if it turns out yours is bad. Bob

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    Quote Originally Posted by J Henricksen View Post
    I thought it might be his way of subtley telling me to find a donor machine.
    I'll put together a full wave bridge and control transformer and see if I can make it work. If so, I'll pull the exciter and take it to a motor shop that I know can figure it out.
    "Rush job" didn't exist, I'd isolate the exciter - belt & wires, as said - and test it first.

    Fairly solid evidence points to it having failed, but is not yet 100% conclusive.

    If there is, for example, but an ignorant break or short downline, misbehaving motor switch or relay, finding and fixing it will be needed anyway, and need not also involve the tedious physical de-mounting of the exciter.

    Bill

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    I am not actually sure what you are calling the "exciter". Been a few years for me but it is just two generators, one generating power for the field, the other power for the armature.

    The piggy back generator does have a wire wound adjustable resistor hooked up in there. If that were to fail, what would happen?

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    There seems to be more than just an exciter that has failed. I think I hooke this up right...
    I did a real cheap and dirty DC rectifier supplied from a multioutlet strip with internal breaker (15 A).
    I slipped the belt off of the generator pulley, disconnected E1 and E2 exciter wires from the terminal strip and replaced them with the +/- from the full wave bridge. I left #3 tied to the generator wire in the taped lugged connection in the box.
    I was expecting either a loud bang and smoke from the rectifier or everything to work normally.
    I had 108 V between E1 and E2
    Moving the forward reverse lever to start the spindle did nothing.

    Back to looking for a bad switch and relay somewhere I guess.
    Did I have this connected properly?

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    Quote Originally Posted by J Henricksen View Post
    There seems to be more than just an exciter that has failed. I think I hooke this up right...
    I did a real cheap and dirty DC rectifier supplied from a multioutlet strip with internal breaker (15 A).
    I slipped the belt off of the generator pulley, disconnected E1 and E2 exciter wires from the terminal strip and replaced them with the +/- from the full wave bridge. I left #3 tied to the generator wire in the taped lugged connection in the box.
    I was expecting either a loud bang and smoke from the rectifier or everything to work normally.
    I had 108 V between E1 and E2
    Moving the forward reverse lever to start the spindle did nothing.

    Back to looking for a bad switch and relay somewhere I guess.
    Did I have this connected properly?
    I pulled 100% of the electricals out of my first Round Dial 10EE so long ago I forget until just now that I DO still have the schematics for it 'as built'.

    I 'think' you've proved the exciter may be OK. Spinning it up and finding it makes DC would support that.

    A 10EE's Motor switch can - among other things - disable itself when in Neutral. It has cams and microswitches that wear, lots of wires and their terminations.

    Relays and contactors are straightforward to test, if tedious. The switch modes not as easy without a schematic.

    If someone more familiar hasn't come along first, I'll drag my schematics out after supper and have a look.

    I do have a not-yet-powered unaltered 1943 MG round-dial I have to power-up eventually, so it will not be time wasted.

    Bill


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