WARNING
THERE IS NO PROVISION FOR IN-SERVICE ADJUSTMENTS
OF CONTACT WIPE AND STROKE. ALL SUCH ADJUSTMENTS
ARE FACTORY SET AND SHOULD NOT BE ATTEMPTED IN
THE FIELD.
Contact Erosion and Wipe
Since the contacts are contained inside the interrupter,
they remain clean and require no maintenance. However,
during high current interruptions, or high numbers of
operations, it is possible for a minimal amount of erosion
on the contact surfaces. It is also possible for further
compaction of the conductor electrodes that has been
known to reduce the amount of contact wipe. The
VR-Series
+
vacuum interrupter assembly incorporates
both the original vacuum interrupter erosion indicator
and the contact-spring wipe into one all-encompassing
indicator. The adequacy of the remaining contact erosion
and wipe can easily be determined by observing the
vacuum interrupter side of the operating rod assembly
on a closed circuit breaker. The procedure to determine
the adequacy of the “T” cutout on the vacuum
interrupter assembly is depicted in Figures 6.1 and 6.2.
Some configurations may require the use of a small
mirror and flashlight to clearly see the “T” cutout. As
long as any part of the “T” cutout is visible on each
pole unit, the contact surfaces and spring pressure are
adequate for the circuit breaker to interrupt its full rated
nameplate short circuit and carry continuous current
without over-heating. If the wipe is inadequate (no part
of the “T” cutout is visible) then the vacuum interrupter
assembly must be replaced. Field adjustment is not
possible.
Vacuum Bottle Contact Inspection
Contact Wipe and Stroke: Blue Contact Springs
ote:N Click the image above to view a satisfactory contact wipe and stroke.
Any part of “T” Cutout Visible - “Wipe” Satisfactory
“T” Cutout Not Visible - “Wipe” Unsatisfactory
WARNING
FAILURE TO REPLACE A VACUUM INTERRUPTER ASSEMBLY
WHEN THE “T” CUTOUT IS NOT VISIBLE WILL CAUSE THE
CIRCUIT BREAKER TO FAIL TO INTERRUPT AND THEREBY
CAUSE PROPERTY DAMAGE OR PERSONAL INJURY.
Contact Wipe and Stroke
Contact wipe is the indication of (1) the force holding the
vacuum interrupter contacts closed and (2) the energy
available to hammer the contacts open with sufficient
speed for interruption.
Stroke is the gap between fixed and moving contacts of
a vacuum interrupter with the circuit breaker open.
The circuit breaker mechanism provides a fixed amount
of motion to the operating rods. The first portion of the
motion is used to close the contacts (i.e. stroke) and the
remainder is used to further compress the preloaded
wipe spring. This additional compression is called wipe.
Wipe and stroke are thus related to each other. As the
stroke increases due to the erosion of contacts, the
wipe decreases. A great deal of effort and ingenuity has
been spent in the design of VR-Series
+
circuit breakers,
in order to eliminate any need for field adjustment of
wipe or stroke.
ote:N It may be necessary to use a small mirror and flashlight to
clearly see the “T” shape indicator. The figure below shows the
procedure for determining the contact wipe of each spring type.
7
EATON | Visual Instruction Booklet Essentials | November 2018
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