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SECTION 15—Renewal Parts
It is recommended that sufficient renewal parts be carried in
stock to enable the prompt replacement of any worn, broken
or damaged parts. A stock of such parts minimizes service
interruptions caused by breakdowns, and saves time and
expense. When continuous operation is a primary
consideration, more renewal parts should be carried, the
amount depending upon the severity of the service and the
time required to secure replacements.
Renewal parts which are furnished may not be identical to the
original parts, but they will be interchangeable.
A separate Renewal Parts Bulletin is available from your local
GE Sales office by asking for GEK-90218.
SECTION 16—Mechanical Adjustments
16.1—General
The ML-18 and ML-18H Mechanism has been designed for
extended intervals between maintenance. In most cases only
the wipe and gap adjustments will require re-setting
throughout the life of the circuit breaker.
16.2—Wipe Adjustment
Wipe is the additional compression of a preloaded spring,
used to apply force to the vacuum interrupter contacts and
to provide opening kick-off force.
The contact wipe adjustment should always be made before
making the contact gap adjustment. An indicator is provided
on the ML-18 wipe spring assembly with graduations given in
0.05 inch on which wipe is indicated directly. See Figure 6.
ML-18 Improved accuracy of the wipe measurement may be
obtained by using a feeler gauge between the top of the wipe
indicator and the erosion disk. The difference in readings on
each pole with the breaker closed and open is the contact
wipe. Adjustment not required if wipe is more than 0.075
inch. After adjustment the wipe should be 0.15-0.18 inch.
ML-18H The wipe measurement is made with the breaker
closed and the closing spring gagged. Measure with a feeler
gauges the distance between the bellville washer and the
trunion between the bell crank arms. Adjustment not required
if wipe is more than 0.075 inch. After adjustment the wipe
should be 0.15-0.18 inch.
To adjust the primary contact wipe, close the breaker and
proceed as follows:
1.
Loosen, but do not remove, the two capscrews (item 9,
Figure 6) holding the interrupter clamp.
2.
Check that the interrupter clamp is loose. A light pry at
the clamp half-junction may be required to loosen the
wedging action of the clamp.
3.
Hold the hexagon projection (6, Figure 6) at the bottom
of the operating rod insulator (1 inch wrench) and loosen
the adjacent locknut (3/4 inch wrench). (Refer to 4,
Figure 6). Adjust by rotating the operating rod insulator.
15.1—Ordering Instructions
1.
Always specify the complete nameplate data of both the
breaker and mechanism.
2.
Specify the quantity, catalog number (if listed), reference
number (if listed), and description of each part ordered,
and the parts bulletin number.
3.
Standard hardware, such as screws, bolts, nuts, washer,
etc. is not listed in this bulletin. Such items should be
purchased locally.
4.
For prices or information on parts not listed in the
Renewal Parts Bulletin, refer to the nearest GE office.
The thread is 1/2-13 and each turn will give about 0.078
inch change in primary wipe. Screw the operating rod
insulator toward the interrupter to increase wipe.
4.
After setting the contact wipe on each phase, torque the
operating rod locknut (item 4, Figure 6) to 40-50 foot
pounds while holding the hex projection (6) to prevent
the operating rod insulator (7) from turning. Tighten the
clamp screws (9) to 8-10 foot pounds and trip the breaker
open. This procedure prevents accidental twisting of the
interrupter's operating rod by loading the contacts with
the wipe springs and forcing relative rotation to occur at
the clamp interface.
After adjustment, re-measure the wipe dimensions. If the
wipe settings are within the required limits, there is an
adequate contact closing relationship between the poles.
16.3—Contact Gap Adjustment
The gap adjustment refers to the separation, or gap, between
the primary contacts within the vacuum interrupter. Before
attempting to measure or set the gap adjustment, verify that
the wipe settings are within acceptable limits. Any change of
the wipe settings will affect the gap settings.
1.
Adjust the outer left and right phases first. The contact
gap must be 0.54-0.60. The adjustment of the outer
phases affects the center phase measurement. With the
breaker in the open position and the closing spring
discharged, locate the gap adjusting nuts on the opening
spring rods connected to the outer phase bell cranks
(Figure 13). Loosen the jamnut on both rods. Back off the
adjusting bolt on the center phase VI stop (Figure 13).
2.
Advance or retard the adjusting nuts depending on which
way you want to change the gap. Move both nuts the
same amount.
3.
Lock the jam nuts after setting the adjusting nuts.
Operate the breaker a few times and remeasure the gap
following the procedure described in DIMENSIONAL
CHECKS, item 3.
4.
Readjust the center phase VI stop (Figure 13). Set
adjusting screw for no clearance between stop and wipe
spring rod striker with the breaker open.
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