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to the positive marked terminal on the rectifier and the negative
(-)
lead
from
the
field
coils
is
connected
to
the
opposite
UNMARKED terminal on the rectifier.
Using
jumpe~
leads with insu-
lated alligator clips, connect 6 to 12 volts DC battery positive
to the positive of the rectifier and negative to the UNMARKED ter-
minal of the rectifier for approximately 10 seconds.
This should
restore magnetism to the stationary field coils.
(Be careful not
to connect DC voltage to the AC terminals on the rectifier,
as
this will damage the rectifier.)
Remove the alligator clip connections; replace the end bell cover
and operate the generator and check AC output voltage.
6.
Check for a short or open in the rotating armature or in the sta-
tionary field coils.
ROTATING ARMATURE (RESISTANCE VALUES)
3.0 & 4.4KW (2-wire)
3.0
& 4.4KW (3-wire)
1 ohm or less slip ring to slip ring
1 ohm or less between slip rings 1 and 3
NOTE:
No continuity should be found between slip rings
(1
&
2)
and (2 & 3) on the 3-wire unit.
(If so, an internal short in the
armature winding exists.)
Replace the armature.
6.5, 7.7, 8.0, 11.0
and l2.5KW
1 ohm or less between slip rings (1
& 3)
and (2
&
4).
NOTE:
3- and 4-wire units:
There should be no continuity found
between slip rings (1
&
2), (2
&
3) and (3
&
4).
If continuity is
found,
an
internal short exists between these windings and
the
armature should be replaced.
NOTE:
All units:
There should be no continuity found between any
of the slip rings and the armature's central steel shaft.
If con-
tinui ty is found,
the windings are shorted to the shaft and the
armature should be replaced.
Rotating
armature
slip rings
are
numbered
from
inboard of
the
generator flywheel end outward to the rear support bearing.
When referring to 2, 3 and 4-wire units, these are the number of
generator output leads being connected to the load.
You will find
on the 11.0 and 12. 5KW units that there are 8 leads corning from
the brush rig and are combined for a total of 4 output leads.
The
number of wires can also be related to the number of slip rings on
the rotating armature.
FIELD COIL RESISTANCE
(TOTAL)
3.0
& 4.4KW
6.5, 7,7
& 8.0KW
11.0 & l2.5KW
32.5 ohms
22.2 ohms
14.2 ohms
134
+5%
+5%
+5%
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