Siemens siprotec 7SA6 User Manual page 415

7SA6 Manual
C53000-G1176-C133-1
external
prot. device
L+
Figure 6-118 Breaker failure protection with phase segregated initiation — example for
initiation by an external protection device with release by a separate set of trip
contacts
Initiation of a single-phase, e.g. "Start L1 only" is valid when the starting input (= trip
command of any feeder protection) appears for only this phase and current flow is
detected in at least this phase. If current flow is not detected, the auxiliary contact
position can be interrogated according to Figure 6-114, dependent on the setting (&KN
%5. &217$&7 = <HV).
The auxiliary contact criterion is also processed for each individual breaker pole. If
however the breaker auxiliary contacts are not available for each individual breaker
pole, then a single-pole trip command is assumed to be executed only once the series
connection of the normally open (NO) auxiliary contacts is interrupted. This
information is provided to the breaker fail protection by the central function control of
the device (refer to Section 6.20.2).
The three-phase starting signal "Start L123" is generated if trip signals appear in more
than one pole (regardless from which protection function). Phase segregated initiation
is then blocked. The input "!%) 6WDUW ZR ," (e.g. from Buchholz protection)
operates in three-phase mode as well. The function is the same as with common
phase initiation.
The additional release-signal "!%) UHOHDVH" (if assigned to a binary input) affects all
starting conditions. Initiation can be blocked via the binary input "!%/2&. %UN)DLO"
(e.g. during test of the feeder protection relay). Additionally, an internal blocking option
is provided.
Trip L1
Trip L1
Trip L2
Trip L2
Trip L3
Trip L3
7SA6
>BF Start L1
>BF Start L2
>BF Start L3
>BF release
Functions
L–
6-233