Siemens siprotec 7SA6 User Manual

Functions
6-274 7SA6 Manual
C53000-G1176-C133-1
6.20.4 Overall Tripping Logic of the Device
Three-Pole
Tripping
In general, the device trips three-pole in the event of a fault. Depending on the version
ordered, (13th position of the ordering code = “4” to “7”) single-pole tripping is also
possible (see below). If, in general, single-pole tripping is not possible or desired, the
output function “5HOD\75,3SK” is used for the trip command output to the circuit
breaker. In these cases the following sections regarding single-pole tripping are not of
interest.
Single-Pole
Tripping
Single-pole tripping only makes sense on overhead lines, on which automatic
reclosure shall be carried out and where the circuit breakers at both ends of the line
are capable of single-pole tripping. In such cases, the faulted phase may be tripped
single-pole and subsequently reclosed; in the case of two-phase and three-phase
faults with or without earth, three-pole tripping is usually carried out.
Device prerequisites for phase segregated tripping are:
• that phase segregated tripping is provided by the device (according to the ordering
code);
• that phase segregated tripping is provided by the protection function which trips
(accordingly not e.g. earth fault protection, high-current switch-on-to-fault
protection, overvoltage protection, overload protection);
• that the binary input “!S7ULS3HUP” is configured and activated or the internal
automatic reclosure function is ready for reclosure after single-pole tripping.
In all other cases tripping is always three-pole. The binary input “!S7ULS3HUP” is
derived from an external automatic reclose device and is equivalent to the logic
inversion of a three-pole coupling signal. This signal is present as long as the external
reclosure is ready for single-pole automatic reclosure.
With the 7SA6, it is also possible to trip three-pole when only one phase is subjected
to the trip conditions, but more than one phase indicates a fault detection. With
distance protection this is the case when two faults at different locations occur
simultaneously but only one of them is within the range of the fast tripping zone (Z1 or
Z1B). This is selected with the setting parameter SROHFRXSOLQJ, which is set to
ZLWK3LFNXS (every multiple-phase
fault detection causes three-pole trip) or ZLWK
7ULS (in the event of multiple-phase
trip commands the tripping is three-pole).
The tripping logic combines the trip signals from all protection functions. The trip
commands of those protection functions that allow single-pole tripping are phase
segregated. The corresponding alarms are “5HOD\75,3/”, “5HOD\75,3/”
and “5HOD\75,3/”.
These alarms can be allocated to LEDs or output relays. In the event of three-pole
tripping all three alarms pick up.
For the local display of fault event messages and for the transmission of event
messages to a personal computer or a centralized control system, the device also
provides a summarized image of the trip signals, e.g. “'LV7ULSS/”, “'LV7ULS
S/”, “'LV7ULSS/” for single-pole tripping as well as “'LV7ULSS” for
three-pole tripping. Only one of these alarms appears at a time. These alarms are also
intended for the trip command output to the circuit breaker.
Single-Pole
Tripping with
Two-Phase Faults
Single-pole tripping for two-phase faults is a special feature. If a phase-phase fault
without earth
occurs in an earthed system, this fault can be cleared by single-pole trip
and automatic reclosure in one of the faulted phases, as the short-circuit path is

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English