4. Press the Trip pushbutton
after completing the contact
erosion check. Visually verify the Discharged condition
of the closing springs and that the circuit breaker con-
tacts are OPEN.
5. Press the Close pushbutton. Nothing should happen.
The manual spring check should demonstrate smooth
operation of the operating mechanism.
Vacuum Interrupter Stroke Check (Figure 25)
Careful use of the setup procedure given in Vacuum Inter-
rupter Replacement Section (under Overhaul) will result in
accurate setting of the stroke and synchronization of the
three phases. The procedure outlined below is useful as a
check following adjustment, replacement or other service
of the operating linkages but is not intended as a substi-
tute for the setup procedure in Vacuum Interrupter Replace-
ment Section. The accuracy of stroke measurement is
highly dependent on the care and consistency used in
making the two marks required.
Figure 25a.
Vacuum Interrupter Stroke Check.
1. Place the breaker in the OPEN position.
2. Apply a piece of .25” wide or narrower tape (correction
tape works well) to the stem of the vacuum interrupter,
as shown in Figure 25a, such that when the stem moves
the tape will enter the grove in the interrupter stem guide
bushing.
3. With breaker still in open position, mark a line on the
tape where it intersects the guide bushing. Close the
breaker and repeat the marking procedure (Figure 25b).
Maintenance
1. Insert the hand charging lever into the manual charge
handle socket at the front of the operator control panel.
Figure 16 shows the lever inserted. Up and down mo-
tion of the lever charges the closing springs. Continue
cranking until the Charged flag appears in the window
of the spring indicator.
2. Press the Close pushbutton. The contact position indi-
cator on the operator control panel should indicate that
the breaker contacts are CLOSED.
3. Perform the contact erosion check. Contact erosion oc-
curs when high fault currents are interrupted or when
the vacuum interrupter is nearing the limit of its contact
life. Determination of acceptable contact condition is
checked by measuring the gap between the end of the
coupling rod and the bottom of the pivot block, shown
in Figure 24. Subtract this measurement from the base
dimension recorded on the decal next to the interrupter
If the difference is 0.22 inch or more, the interrupter must
be replaced.
Figure 24.
Contact Erosion Check.
Hazardous voltages and high-speed
mechanical parts.
Will cause death, serious injury or property
damage.
Read instruction manuals, observe safety
instructions and use qualified personnel.
Tripping spring is charged.
If trip latch is moved, high-speed movement
of components can cause serious injury.
Observe precautions concerning physical
contact with components of the circuit
breaker subjected to sudden, high speed
movement.
2095-98
24
2134-99
2135-99
Groove
Tape