Table of Contents
Advertisement
2.7
Teleprotection for Distance Protection (optional)
2.7.1
General
Purpose of Teleprotection
Faults which occur on the protected line, beyond the first distance zone, can only be cleared selectively by the
distance protection after a delay time. On line sections that are shorter than the smallest sensible distance set-
ting, faults can also not be selectively cleared instantaneously.
To achieve instantaneous and selective tripping on 100 % of the line length for all faults by the distance protec-
tion, the distance protection can exchange and process information with the opposite line end by means of tele-
protection schemes. This is realized by means of send and receive contacts.
As an alternative, digital communication lines can be used for signal transmission.
Teleprotection Schemes
A distinction is made between underreach and overreach schemes.
In underreach schemes, the protection is set with a normal grading characteristic. If a trip command occurs in
the first zone, the other line end receives this information via a transmission channel. There the received signal
initates a trip, either by activation of overreach zone Z1B or via a direct trip command.
7SD5 allows:
• PUTT (Pickup),
• Permissive Underreach Transfer Trip with Zone Acceleration Z1B (PUTT),
• Direct (Underreach) Transfer Trip
In overreach schemes, the protection works from the start with a fast overreaching zone. This zone, however,
can only cause a trip if the opposite end also detects a fault in the overreaching zone. A release (unblock) signal
or a block signal can be transmitted. The following teleprotection schemes are differentiated:
Permissive (release) schemes:
• Permissive Overreach Transfer Trip (POTT) with overreaching zone Z1B
• Directional comparison,
• Unblocking with overreaching zone Z1B.
Blocking scheme:
• Blocking of overreaching zone Z1B.
Schemes via pilot wire:
• Pilot Wire Comparison
• Reverse Interlocking
Since the distance zones function independently, an instantaneous trip in Z1 without a release or blocking
signal is always possible. If fast tripping in Z1 is not required (e.g. on very short lines), then Z1 must be delayed
with T1.
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
2.7 Teleprotection for Distance Protection (optional)
Functions
187
Advertisement
Table of Contents
