Functions
2.11 Measures for Weak and Zero Infeed
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
282
Trip with delay
The operation of the delayed tripping is determined by three parameters:
• Address
2517
1pol. Trip
enables a single-pole trip command for phase-to-ground faults if it is parame-
terised to
ON
• Address
2518
1pol. with 3I0
, if set to
ON
, allows a single-pole trip command only if also the threshold
3I0> Threshold
for the zero current has been exceeded. If the threshold
3I0> Threshold
is not ex-
ceeded, phase-to-ground faults do not cause a tripping. Position
OFF
allows a single-pole trip command
even when
3I0> Threshold
is not exceeded. The time delay of „3I0> exceeded“ is set at address
2513
T 3I0> Ext.
.
• Address
2519
3pol. Trip
, if set to
ON
, also allows a three-pole trip command in the event of a multi-pole
pickup. In position
OFF
only the multi-pole pickup is reported but a three-pole trip command is not issued
(only reporting). A 1-pole or 3-pole trip command for 1-pole pickup can still be issued.
A delayed tripping stage is implemented to allow tripping of the dedicated line end in case the transmission
channel is faulted. When undervoltage conditions have been detected, this stage picks up in one or more
phases and trips with delay after a configured time (address
2515
TM
and address
2516
TT
) depending on the
set stage mode (address
2517
1pol. Trip
and
2519
3pol. Trip
). If no trip command is issued during a
pickup after the times
2515
TM
and
2516
TT
have elapsed, the voltage memory is reset and the pickup is can-
celled.
Address
2531
WI delayed
allows to set delayed tripping as operating mode. With
ON
this stage is perma-
nently active. With the setting
by receive fail
, this stage will only be active when
„>WI rec. OK“
is not
true. With
OFF
this stage is permanently switched off.
To avoid erroneous pickup, phase selection via undervoltage is blocked entirely in the event of voltage failure
(pickup of the fuse failure monitor or of the VT mcb). In addition, the relevant phases are blocked when the
distance protection function is activated.