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what does the exciter do on a 10ee MG?

lectrician1

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Mar 6, 2012
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Las Vegas
i just got a 10ee round dial MG with a DC power supply hooked right into the exciter terminal box. The dc supply is delivering 86.27volts DC. So far I have the spindle running in both directions up to about 2200 rpm. Can anyone explain the function of the exciter?
Spindle motor will not operate unless the dc power supply is on.
Does the exciter still need to be spinning via the belt if there is DC voltage coming from elsewhere?

thanks
Rich
 
i just got a 10ee round dial MG with a DC power supply hooked right into the exciter terminal box. The dc supply is delivering 86.27volts DC. So far I have the spindle running in both directions up to about 2200 rpm. Can anyone explain the function of the exciter?
Spindle motor will not operate unless the dc power supply is on.
Does the exciter still need to be spinning via the belt if there is DC voltage coming from elsewhere?

thanks
Rich
If you have an add-on DC supply it's probably because the exciter failed. You can take the belt of an just leave it there.

The exciter provides power for three things: 1) the DC control panel, 2) the spindle motor's field, and 3) the DC generator's field. The big pair of Ohmite rheostats vary the voltage provided by the exciter to the spindle motor and generator fields to provide the variable speed "magic". One rheostat ramps up the voltage to the generator's field, causing it to increase its output voltage, which is provided to the spindle motor's armature. The other rheostat then kicks in to reduce the voltage to the spindle motor's field, weakening the field and causing the motor to run faster.

Cal
 
Thank you Cal! Next question is should the voltage be closer to 90v. Dc from the supply? I am wondering if the power supply voltage has anything to do with the spindle motor not reaching 2500rpm. Thank you very much for your help
Rich
 
Thank you Cal! Next question is should the voltage be closer to 90v. Dc from the supply? I am wondering if the power supply voltage has anything to do with the spindle motor not reaching 2500rpm. Thank you very much for your help
Rich

The exciter puts out 115 VDC, but around 90 VDC is about as well as you're going to do with a simple rectifier. If the generator's field doesn't get full voltage, it won't put out full voltage to the spindle motor, so it will definitely keep the motor from reaching full speed. Some exciter replacement circuits include a small boost transformer to pump up the input to the rectifier enough that it puts out 115 VDC. And depending on what type of meter you have, the DC waveform may be fooling the meter and not giving you an accurate voltage value.

Cal
 
how many amps does the exciter supply? or how many amps should my new power supply be rated at? i would like the machine to be able to operate at 2500rpm. or would it be easier to find another exciter?
 
I have never worked on a round dial, so this isn't gospel, but in my experiments with a square dial with a Reliance MG the speed vs load characteristics were much better with a regulated supply. They are pricey new but they often show up in surplus stores at low prices. They also have the advantage that you can set the voltage to suit.

Bill
 
I noticed on a generator/exciter for sale on ebay that the amperage is 2.4. I just ordered a chinese 120v DC variable power supply that can handle 3amps. It was cheap so i thought i would give it a try. I'll keep you posted on the results.
Thanks for the assistance
Rich
 
thanks Thermite
i just bought a parker ssd 506 on ebay used for $70 as per your suggestion.
i will try both the parker and the chinese one and see which works best
 








 
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