Maintenance
Table 2: Maintenance Tasks
• Checks of the Primary Power Path
• Checks of the Interrupter Operator Mechanism
• Electrical Control Checks
• High Potential Test
• Inspection and Cleaning of Breaker Insulation
• Functional Tests
For a “quick reference” to these tasks, see “Periodic Main-
tenance and Lubrication Tasks” chart on page 39.
The list of tasks in Table 2 does not represent an exhaus-
tive survey of maintenance steps necessary to ensure safe
operation of the equipment. Particular applications may
require further procedures. Should further information be
desired or should particular problems arise which are not
covered sufficiently for the purchaser’s purposes, the mat-
ter should be referred to the local Siemens sales office.
De-energize the Circuit Breaker
Prior to performing any inspection or maintenance checks,
the circuit breaker must be de-energized and grounded.
Principal steps are outlined below for information and guid-
ance.
Be sure that the circuit breaker and its mechanism are dis-
connected from all electric power, both high voltage and
control voltage, before it is inspected or repaired.
After the circuit breaker has been disconnected (isolated)
from power lines, attach the grounding leads properly be-
fore touching any of the circuit breaker parts.
De-energize the control power to the circuit breaker. Re-
view Figure 6. If the circuit breaker includes the optional
capacitor trip unit, the capacitor must be discharged by
grounding its terminals.
Perform the Spring Discharge Check, by first pushing the
Trip pushbutton, then the Close pushbutton, and finally the
Trip pushbutton again. Verify that the circuit breaker is
OPEN and the closing spring indicator shows DISCHARGED.
See Figure 21, which shows the breaker condition preced-
ing the second operation of the Trip pushbutton.
Figure 21.
Manual Tripping of Circuit Breaker.
Checks Of Primary Power Path
The primary power path consists of the three vacuum in-
terrupters, six bus connections to the bushings, and the
roof mounted bushings. These components are checked
for cleanliness and condition. The vacuum interrupters are
also checked for vacuum integrity.
Some test engineers prefer to perform the contact erosion
check during the manual spring charging check of the op-
erator, since charging of the springs is necessary to place
the contacts in the closed position.
Also, the vacuum integrity check is usually performed in
conjunction with the High Potential tests.
These instructions follow the recommendation that these
tests (contact erosion/manual spring charging check, and
vacuum integrity/high potential tests) will be combined as
described.
Cleanliness Check - Figure 22 is a side view of the type
SDV circuit breaker with one of the insulating phase barri-
ers (when so equipped) removed to show the vacuum in-
terrupter, bus connections and roof bushings.
All of these components must be cleaned and free of dirt
or any foreign objects. Use a dry lint-free cloth. For stub-
born dirt, use a clean cloth saturated with denatured alco-
hol.
Also inspect the buswork for any evidence of loose bolts,
bushings for any evidence of damage, and flexible con-
nectors for tightness and absence of mechanical damage,
burning, or pitting.
The use of unauthorized parts in the repair of the equipment,
or tampering by unqualified personnel will result in
dangerous conditions which can cause death, serious injury
or equipment damage.
Follow all safety instructions contained herein.
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