TM 9-6115-604-34NAVFAC P-8-633-345-22. LOAD CIRCUIT BREAKER CB1O1AULGNMENT. The following alignments must be made when a vacuuminterrupter assembly is replaced. The primary contact gap must also be set when a return spring is replaced. Thesealignments 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). Adjustmentis performed by loosening the jam nuts on the drive linkage shaft. Be certain to tighten the jam nuts after obtaining thecorrect dimension.WARNINGWhenever a procedure Is to be performed with the drive springs In the charged position, It Ismandatory to block the drive springs by placing the blocking pins (105, Figure 5-19) In theholes at the upper end of the drive spring center shafts. (The blocking pins are located In thetool box). See Figure 4-1 of the Operator and Organizational Maintenance Manual for thelocation 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 tobe 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 positionand 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 driveconnecting links (Figure 5-1 5); only the first method may be used on the center drive connecting link (a) Remove thenut, 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 tolengthen the overtravel. Remove tool T-1. Install the washer, lockwasher, and nut on the drive connecting link Recheckand readjust until proper dimensions are achieved.NOTEThis 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 springretainer (Figure 5-20) with a wrench and turn the erosion indicator clockwise to shorten or counter-clockwise to lengthenthe overtravel. Retighten nut, lockwasher, and washer at the top of the drive connecting link Recheck and readjust untilproper dimensions are achieved.c.Primary Contact Gap. With the load circuit breaker CB101 in the OPEN position, the primary contact gap shall be0.625 to 0.800 inch (15.88 to 20.32 mm). To determine the primary contact gap, use a telescoping gauge andmicrometer (0-1 inch) to measure distance D (Figure 5-21) with the breaker in the OPEN position, then with the breakerin the CLOSED position, remeasure distance D. The difference between these two measurements is the primary contactgap. To adjust the primary contact gap, proceed as follows: CAUTION This procedure Is performed with the returnsprings In the charged position.NOTEThis 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 isin the open position.5-52
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