Baker D30R, User'S Manual & Operating Instructions

Page: 95 / 142

D30R Users Manual
95
Do Not Touch Test Leads while test is in Progress!
71-023 Rev C 5/8/2007
The wave pattern produced in this test represents the voltage oscillation between
the tester and the coils for the specific number of commutator bars spanned. For
example, any 10 bars spanned in series on the armature should give the same
pattern as any other 10 bars spanned. As the armature is rotated, all the
commutator segments and therefore their respective coils, pass into the “test
area” between the Hot surge test lead and the GRD lead.
Note
: It is important that the same number of bars (and therefore coils) always
be in the “test area”. The test wave pattern for each span should match a
reference wave pattern on the display for the complete armature if the coils are
all good.
1. Remove all brush pig tail connections from the leads at the brush
rigging for all sets of brushes to isolate the armature from the power
source.
2.
With the TLS switch in the LEADS GROUND position, connect test
lead #1 to one of the brush assembly pigtails. Connect the GRD test
lead to the shaft or other good ground on the frame.
Note
: When testing armatures that have bars that are wired in series, it is very
important to ground at least two bars of the armature a few bars away from those
that are being surged. If this is not done, very high potential voltages to ground
can develop in the armature due to a transformer effect in the coil.
3. Select the adjacent set of brushes or the brushes of the bar
corresponding to the desired span. Connect test lead #2 and #3 to the
pigtail of that brush assembly.
4.
Select the TLS position #1. Be sure the Function switch is set to Surge.
5. Begin the test by pressing the test button or footswitch and slowly
raising the Output control to the desired test voltage level. Carefully
observe the wave pattern for its reference shape.
6. Store this wave pattern as the “reference” wave pattern for this span on
this particular armature. Recall the reference wave pattern to the
display ( Use Quick Store if desired). Note the Peak Voltage displayed
on the screen.
7. Begin testing again using the same Output voltage until the test wave
pattern matches the reference wave pattern.