Siemens siprotec 7SA522 User Manual page 353

7SA522 Manual
C53000-G1176-C119-2
external
prot. device
L+
Figure 6-102 Breaker failure protection with phase segregated initiation — example for initia-
tion by an external protection device with release by a fault detection signal
external
prot. device
L+
Figure 6-103 Breaker failure protection with phase segregated initiation — example for initia-
tion 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 de-
tected in at least this phase. If current flow is not detected, the auxiliary contact posi-
tion can be interrogated according to Figure 6-100, 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 informa-
tion is provided to the breaker fail protection by the function control of the device (refer
to Section 6.14.2 ) .
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 "Start without I" (e.g. from Buchholz protection) operates in
three-phase mode as well. The function is the same as with common phase initiation.
Trip L1
Trip L2
Trip L3
Pick-up
Trip L1
Trip L1
Trip L2
Trip L2
Trip L3
Trip L3
7SA522
>BF Start L1
>BF Start L2
>BF Start L3
>BF Release
7SA522
>BF Start L1
>BF Start L2
>BF Start L3
>BF Release
Functions
L–
L–
6-205