[SEL] Generator hookup

[Jim Dragoset]

Rick,
You would expect an eight pole DC machine to have eight brushes spaced
evenly around
the commutator. They would in turn alternate +,- around so all the + brushes
would
connect together and all the - brushes would connect together.
A valid test would be to separate all connections and energize the field
winding with a 12 volt battery.
With the machine up to speed you should measure a voltage between any two
adjacent brushes.
Mark the field wire and brushes that are positive.
You would also want to get a current reading through the field winding.
If the field is intended to be self-excited, The current at 250 volts should
be under 1 amp
which would correspond to under 48 milliamps with a 12 excitation.
The field current test can be done with the machine no spun up.
Be careful when you disconnect the 12 volts from the field as there will be
a high voltage back- kick.
It is possible your machine only had four brushes originally 2+ and 2-
Self excitation connection would be positive field wire to positive brush,
negative field wire through rheostat (maybe as large as 250-500 ohms, 250
watts) to negative brush.
When you get it up to 250 volts try connecting the positive brushes together
and the negative brushes together provided their voltages are equal. check
that current between two brushes is zero with no load.
I would strongly recommend checking with a megger to 500 volts to make sure
all insulation of windings is good before attempting a rated output voltage
run.
Good luck,
Jim Dragoset,NOLA

-----Original Message-----
From: sel-bounces at lists.stationary-engine.com
[mailto:sel-bounces at lists.stationary-engine.com]On Behalf Of Richard
Strobel
Sent: Tuesday, May 10, 2005 11:38 AM
To: sel
Cc: Elden DuRand
Subject: [SEL] Generator hookup


  Howdy all with Elden on the side.

    Need some help getting this ole girl excited :-)

   Generator rated at 250 VDC @ 16 amps.

   If you can't read the legend on the pix. it's as follows:

   A is connected to the 4 brushes

   B is connected to one of the field coil winding

   C looks like it's connected to the other winding in the field coil.

   Pix at:

http://community.webshots.com/photo/291395326/342708600ebaRxX

  Tanks much!!

  RickinMt.
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