Baker D30R, User'S Manual & Operating Instructions

Page: 96 / 142

D30R Users Manual
96
Do Not Touch Test Leads while test is in Progress!
71-023 Rev C 5/8/2007
Note
: The Zero Start Interlock is disabled only when the Funtion switch is set
to AT101 for the AT101D accessory (See Supplement #: Model AT101D) and
the Footswitch is depressed. Without the accessory and a footswitch, the Output
must be turned back to zero or Min and then brought back up to the peak voltage
value noted above in Step 6. The same test voltage must be used for each span
tested.
8. Rotate the armature slowly through 360 degrees so that all commutator
segments are tested while observing the reference wave pattern.
Note
: It is recommended to release the Test button (or Footswitch) each time
the armature is turned, but it is not necessary. Doing so minimizes the chance of
marking the commutator.
If the test button or footswitch is not released each time the armature is turned,
the wave pattern will show regular shifts and flickers as the brushes move across
one commutator bar to the next. This wave pattern movements should be
ignored as long as the trace returns to the reference wave pattern and remains
stable when the brushes are again centered on top of the bars.
Determination of a Fault
If the insulation is weak or failing on a particular bar or coil of the armature, the
test wave pattern will become unstable and Shift Left when the section that
contains the fault passes through the “test area”. The test wave pattern will no
longer match the reference wave pattern. This indicates shorted windings within
the span.
Usually, as soon as the bad bar is placed under the hot brush, the wave pattern
will show the shift to the left as noted above. Thus the bar directly below the
hot brush is the faulty bar. An example of a fault found surge testing using the
motor’s brushes is illustrated below.