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MAINTENANCE Page 23
ELECTRICAL SERVICE LIFE
The electrical service life of the vacuum
interrupter is defined by the electrode wear and
the number of open/close operations
(mechanical life).
To determine electrode wear, measure the
distance between the lever and washer in the
closed (ON) state, as shown in Figure 13. This
dimension is called the “wipe”. If the 1.0mm
contact wear gauge cannot be inserted, then
the end of the service life has been reached.
The maximum number of open/close operations
is 500,000 regardless of the magnitudes of the
currents interrupted. Contact Toshiba for
information regarding replacement of the
vacuum interrupters.
The drive unit and the closing coils also have
an electrical service life of 500,000 operations.
As a result, these parts should be replaced
around 500,000 operations.
MECHANICAL SERVICE LIFE
The normally energized type has a mechanical
service life of 2.5 million operations. The
mechanical service life of the vacuum
interrupters is 500,000 operations.
For the components listed in Table 4,
replacement or detailed inspection and cleaning
are recommended after the indicated number of
operations.
Figure 13 - Wipe Measurement
Table 4 - Recommended Part Replacement
Intervals
Part Name Number of Operations
for Replacement
Vacuum Interrupter 500,000
Auxiliary Switch 200,000
Moveable Core Detailed inspection and
cleaning every 500,000
operations.
Stationary Core Detailed inspection and
cleaning every 500,000
operations.
Closing Coil 500,000
Flexible Conductor 500,000
SERVICE LIFE – CAPACITOR SWITCHING
Switching of the capacitor loads produces
severe conditions for contactors, such as high
frequency inrush current and phase-to-phase
recovery voltage more than twice the normal
voltage.
The criterion for the maximum number of the
capacitor current switching operations is shown
in Figure 14. The vacuum interrupter should be
replaced when the number of switching
operations in the graph is reached.
Figure 14 - Capacitor Switching Life
1
10
10 100 1000
Switching Current (A)
Switching Life (ten thousand)
6
4
8
20 40 60 200 400 600
A
Isolation
Flange
2
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