Siemens 3AH3, Operating Instructions Manual

Page: 34 / 64

Description
34 9229 9860 176 0E
2013-08-22
Priority opening
To lock the OPEN position, the drive mechanisms of the vacuum circuit-breaker can
be equipped with “priority opening”. This is also the case for vacuum circuit-breakers
on switch gear trucks, in withdrawable sections or with disconnectors.
Fig. 45 Priority opening
The assembly “priority opening” has three positions. These positions are actuated
by an interrogation or actuation component in the system.
Trip-free position When actuating “priority opening” by putting into first position on the system (trip-free
position, b), opening is triggered, closing is prevented and reclosing is reliably pre-
vented as well.
Spring-dump position In the second position (spring-dump position, c) the vacuum circuit-breaker remains
in open condition.
In addition, when actuating the locking device in the second position, the closing
spring is discharged by a no-load switching operation.
The closing and the opening springs are now discharged and hence all of the energy
storages of the vacuum circuit-breaker are also discharged.
The operating position (CLOSED/OPEN) of the vacuum circuit-breaker is not inter-
rogated with “priority opening”.
a) b) c)
a) Idle position
b) Trip-free position
c) Spring-dump position
*)
Interrogation or actuation component (min. actuation force 70 N)
Note
Compared to the mechanical locking device (see Fig. 32), actuation of the sys-
tem's interrogation and actuation component is not prevented if the vacuum cir-
cuit-breaker is closed.