GE Industrial Solutions PowerVac PV-VL 13.8-1000-0 and -1 - Manual (Page 9)

GEH 6468A - Power/Vac VL Breaker Page 9
2. The gap between the top of the plunger on the
breaker and the bottom of the rod on the stationary
auxiliary switch mechanism.
3. Variations between breakers in the distance
from the underside of the lift rail and the top of the
plunger.
4. Variations in the rotation requirements to
“make” and “break” the stationary auxiliary switch
contacts.
5. Condition of the plunger interlock components
on the breaker.
6. Elevating mechanism limit switch consistency.
7. Breaker elevating mechanism positive stops.
8. Seismic events.
Some of these elements also affect the other
important interfaces required for reliable operation
of the equipment, such as:
1. Primary disconnect penetration.
2. Secondary coupler penetration.
3. The positive interlock mechanism.
A major goal in the design of switchgear has
always been the interchangeabililty of breakers.
GE Switchgear has been very successful in
achieving that goal for many years. Analysis of
instruction book adjustments, shop tolerances, and
service advice letters issued in recent years,
however, has demonstrated that tolerances in
switchgear equipment installed and presently
operating can result in situations where it is
impossible to meet all adjustments or that an
adjustment is brought into specification and it
causes a problem with another interface.
With specific reference to the plunger / stationary
auxiliary switch interface, the following instructions
and recommendations supersede all previous
Service Advice Letters and instructions. Refer to
Figure 1 for details.
Nominal breaker plunger travel is 1-1/8”. Nominal
auxiliary switch rod travel is 1-1/16”. It is
imperative that a gap is present between the top of
the plunger and the bottom of the rod, when the
breaker is in the fully connected position and the
breaker is open.
To assure the most reliable switch operation, it is
recommended that the plunger travel be measured
for each breaker and recorded in maintenance
records. It is further recommended that the
auxiliary switch mechanism be adjusted, if
necessary, to result in a gap that is in accordance
with the table given in Figure 10. It may require the
roll pin which
secures the auxiliary switch mechanism plate to be
removed and a new hole drilled after loosening the
two mounting bolts and moving the entire auxiliary
switch mechanism up or down.
This action may mean future adjusting when and if
different breakers are interchanged. Reliable
switch operation is critical and it may require
limiting your interchangeability of breakers. At a
minimum, the criticality requires adjustment
verification when swapping breakers.
Specifically, paragraph (f) on page 11 of Service
Advice Letter (S.A.L.) #073-323-1, dated 02-01-78
is rescinded and the instruction in GEH-1802X on
gap clearance is rescinded and both are replaced
with the gap dimension (“G”) given in the table of
Figure 10.
The plunger dimensions given in the breaker
instruction books are not rescinded because they
are correct nominal dimensions. It is permissible to
let the breaker adjustment be out of specification, if
it conflicts with the dimensions given in Figure 10.
5.2 PRIMARY CONTACT PENETRATION
The nominal contact penetration is 7/8” as shown
in Figure 11. The tolerance on penetration is plus
5/32”, minus 1/8” on non 1E equipment and plus
1/16”, minus 1/8” on 1E equipment.
Reference Service Advice Letter # 073.323.1,
which addresses methods to check both the
penetration and the contact wipe for 5kV
equipment. The same methods and means of
adjustment also apply to 15kV equipment. GEH-
1802X and the similar illustrations it contains
showing proper contact wipe patterns should also
be consulted. It is essential to maintain proper
contact penetration while maintaining the
stationary auxiliary switch adjustment given in
Figure 10.
5.3 POSITIVE INTERLOCK
The purpose of the positive interlock it to prevent
moving the breaker to or from the connected
position while the main contacts are closed, and to
prevent closing the contacts unless the breaker is
in the fully connected position. These important
safety features are achieved by means of the
positive interlock roller on the right side of the
breaker and positive interlock cam and stationary
“flag” on the switchgear, as shown in Figure 7.