Overhaul; Introduction; Circuit Breaker Overhaul; Replacement At Overhaul - Siemens SDV-4A Instruction Manual

Overhaul

Introduction

The following procedures along with the troubleshooting
charts at the end of this section, provide maintenance per-
sonnel with a guide to identifying and correcting possible
malfunctions of the type SDV vacuum circuit breaker.
Hazardous voltages and high-speed moving
parts.
Can cause death, serious injury, or property
damage.
All replacement of breaker components
must be performed with the breaker
completely de-energized and the springs
discharged.
Circuit Breaker Overhaul - Table 6 lists the recommended
overhaul schedule for type SDV circuit breakers operating
under ANSI usual conditions. When actual operation con-
ditions are more severe, overhaul periods should occur
more frequently. The counter on the front panel of the cir-
cuit breaker records the number of operations.
Table 6 Overhaul Schedule
ANSI Usual Conditions
Maintenance Based Upon Number of Closing Operations
Breaker Type
SDV-4A
Replacement At Overhaul - The following components are
replaced during an overhaul of the circuit breaker, when
required:
• Vacuum interrupters as determined by vacuum integ-
rity test, contact erosion, or after 10,000 operations.
• Spring charging motor brushes should be replaced af-
ter 10,000 operations (reference kit 18-658-612-886).
Number of
Closing Operations
5,000
Figure 29. Use of Socket Wrench to Release Tension on
Closing Springs.
Replacement Of Closing Springs - Figure 29 shows the use
of a 3/4 inch socket wrench to relieve spring tension on the
closing springs. The bottom of the breaker operator frame
has openings providing access to the tensioning bolts.
Turning the left and right hand support bolts counterclock-
wise relieves spring tension. Alternate from the left bolt to
the right bolt in small increments. This keeps the sliding
cross arm relatively level as the tension is removed from
the springs.
Each upper spring hanger is fastened to a crank arm using
a hex socket shoulder bolt and nut. The nut is applied us-
ing thread locking adhesive, Loctite 271, with Loctite type
T primer.
When springs are reinstalled, be sure the support bolts are
inserted inside their support bolt bushings. These bush-
ings maintain the correct tension on the closing springs.
Replace all retaining rings during the re-assembly. Re-
tighten by turning the support bolts counterclockwise, al-
ternating sides to keep the crossbar approximately level,
until the support bolt bushings firmly butt up against the
support bolt attachment bracket and the cross arm sup-
port shaft.
2096-98
31