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 the electrode wear, measure
dimension A between the lever and washer in
the closed (ON) state, as shown in Figure 12.
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 wipe surfaces must be lubricated
with contact grease if dry or every 20,000
operations.
The drive unit and the closing coils also have
an electrical service life of 250,000 operations.
As a result, these parts should be replaced
around 250,000 operations.
MECHANICAL SERVICE LIFE
The magnetically held type has a mechanical
service life of 1 million operations and the
mechanically latch type 250,000 operations.
The mechanical service life of the vacuum
interrupters is 250,000 operations.
For the components in Table 4, replacement or
detailed inspection and cleaning are
recommended after the indicated number of
operations.
Figure 12 - Wipe Measurement
SERVICE LIFE – CAPACITOR SWITCHING
Switching of 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
capacitor current switching operations is shown
in the graph below. The vacuum interrupter
should be replaced when the number of
switching operations in the graph is reached.
Table 4 - Recommended Part Replacement
Intervals
Part Name
Number of Operations
for Replacement
Vacuum Interrupter
250,000
Auxiliary Switch
250,000
Moveable Core
Detailed inspection and
cleaning every 250,000
operations.
Stationary Core
Detailed inspection and
cleaning every 250,000
operations.
Closing/Trip Coil
250,000
Flexible Conductor
250,000
Figure 13 - Capacitor Switching Life
(With 6% reactor)
A
1
10
10
100
1000
Switching Current (A)
Sw
itc
hi
ng Li
fe
(t
en t
hous
and)
20 40 60 200 400 600
8
6
4
2
