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 Indicator
Eaton’s VR-Series vacuum contacts are contained
inside the interrupter, where they remain clean and
require no maintenance. However, during high current
interruptions there may be a minimal amount of erosion
from the contact surfaces. If contact erosion reaches
approximately 1/8 inch, the interrupter must be replaced.
The purpose of the contact erosion indicator is to
monitor the erosion of the vacuum interrupter contacts.
A contact erosion indicator mark is located on the
moving stem of the interrupter.
In order to determine if the contacts have eroded to the
extent that the interrupter must be replaced, close the
circuit breaker and observe the erosion mark placed on
each vacuum interrupter moving stem from the rear of
the circuit breaker. If the mark on the interrupter stem
is visible, erosion has not reached maximum value thus
indicating satisfactory contact surface of the interrupter.
If the mark is no longer visible, the vacuum interrupter
assembly must be replaced.
The erosion indicator is easily viewed from the rear on
the 18WR or 29WR element designs. Because of the
nature of the 5kV 20-WR element inverted design, the
erosion indicator is not easily viewed, although it is
possible with the use of a light and a dental type mirror.
Vacuum Bottle Contact Inspection
WARNING
FAILURE TO REPLACE A VACUUM INTERRUPTER ASSEMBLY
WHEN CONTACT EROSION MARK IS NOT VISIBLE OR WIPE
IS UNSATISFACTORY, WILL CAUSE THE CIRCUIT BREAKER
TO FAIL TO INTERRUPT AND THEREBY CAUSE PROPERTY
DAMAGE OR PERSONNEL 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.
The adequacy of contact wipe, as well as the overall
system condition, can be determined by simply
observing the vacuum interrupter side of the operating
rod assembly on a closed circuit breaker. The visible
“T” shape cutout on the loading spring is an indicator
used to determine whether the loading springs are
maintaining the proper contact pressure to keep the
contacts closed. Severe contact erosion would result
in an unacceptable implication from the “T” shape
indicator. If the wipe is not adequate, the vacuum
interrupter assembly (Pole Unit) must be replaced. Field
adjustment of the vacuum interrupter assembly is not
possible.
otee:
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.
If any part of the Red or Gray
indicator is visible:
“Wipe” is Satisfactory.
If any part of the T-Shape Cutout
indicator is visible:
“Wipe” is Satisfactory.
If any part of the Red or Gray indicator
is NOT visible:
“Wipe” is Unsatisfactory.
If any part of the T-Shape Cutout
indicator is NOT visible:
“Wipe” is Unsatisfactory.
Contact Wipe and Stroke: White Contact Springs
Contact Wipe and Stroke: Blue, Red, or Brown Contact Springs
otee:
N
Click the image below to view a satisfactory contact wipe and stroke.
7
EATON
| Visual Instruction Booklet Essentials | DST-2-VR - 18WR Element | May 2017
