TM 9-6115-604-34
NAVFAC P-8-633-34
5-22. LOAD CIRCUIT BREAKER CB1O1AULGNMENT. The following alignments must be made when a vacuum
interrupter assembly is replaced. The primary contact gap must also be set when a return spring is replaced. These
alignments are listed in the order in which they must be performed. Refer to paragraph 5-24 and remove cover (1,
Figure 5-19) and phase insulator assembly (18) to perform these adjustments.
a.
Drive Linkage. Distance B(Figure 5-18) for the drive linkage shall be23/16±1/16inch (55.56i1.59 mm). Adjustment
is performed by loosening the jam nuts on the drive linkage shaft. Be certain to tighten the jam nuts after obtaining the
correct dimension.
WARNING
Whenever a procedure Is to be performed with the drive springs In the charged position, It Is
mandatory to block the drive springs by placing the blocking pins (105, Figure 5-19) In the
holes at the upper end of the drive spring center shafts. (The blocking pins are located In the
tool box). See Figure 4-1 of the Operator and Organizational Maintenance Manual for the
location of the tool box.
b.
Spring Overtravel. When the breaker is in the CLOSED position, the spring overtravel (distance E, Figure 5-20)
must be 0.188 +.06/-0 inch (4.78 +1.5/-0 mm). The following procedure applies to new vacuum interrupters and is not to
be performed on existing vacuum interrupters, as this gap provides contact erosion information (see paragraph 518,
above). For new vacuum interrupters, proceed as follows: (1) With the load circuit breaker in the fully CLOSED position
and the drive springs charged, check the spring overtravel (distance E).
(2) If adjustment is necessary, either of the two methods described below may be used to adjust the two outer drive
connecting links (Figure 5-1 5); only the first method may be used on the center drive connecting link (a) Remove the
nut, lockwasher, and washer (Figure 5-20) at the top of the drive connecting link insert spring overtravel adjusting tool
(05464) T-1 into slots in the end of the erosion indicator. Turn tool T-1 clockwise to shorten or counter-clockwise to
lengthen the overtravel. Remove tool T-1. Install the washer, lockwasher, and nut on the drive connecting link Recheck
and readjust until proper dimensions are achieved.
NOTE
This method of adjustment may only be used on the two outer drive connecting links.
(b)
Loosen the nut, lockwasher, and washer at the top of the drive connecting link Grasp the bottom spring
retainer (Figure 5-20) with a wrench and turn the erosion indicator clockwise to shorten or counter-clockwise to lengthen
the overtravel. Retighten nut, lockwasher, and washer at the top of the drive connecting link Recheck and readjust until
proper dimensions are achieved.
c.
Primary Contact Gap. With the load circuit breaker CB101 in the OPEN position, the primary contact gap shall be
0.625 to 0.800 inch (15.88 to 20.32 mm). To determine the primary contact gap, use a telescoping gauge and
micrometer (0-1 inch) to measure distance D (Figure 5-21) with the breaker in the OPEN position, then with the breaker
in the CLOSED position, remeasure distance D. The difference between these two measurements is the primary contact
gap. To adjust the primary contact gap, proceed as follows: CAUTION This procedure Is performed with the return
springs In the charged position.
NOTE
This procedure must be performed if a vacuum interrupter or return spring has been replaced.
To facilitate this adjustment after a return spring has been replaced, the initial setting
(distance C, Figure 5-21) should be approximately 9 5/8 inches (244 mm) when the breaker is
in the open position.
5-52
