ABB RELION RET670, Applications Manual

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Section 16 Scheme communication
16.1 Scheme communication logic for distance or
overcurrent protection ZCPSCH(85)
IP15749-1 v3
16.1.1 Identification
M14854-1 v4
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Scheme communication logic for
distance or overcurrent protection
ZCPSCH - 85
16.1.2 Application
IP15020-1 v1
M16866-3 v5
To achieve fast fault clearing for a fault on the part of the line not covered by the
instantaneous zone 1, the stepped distance protection function can be supported with
logic that uses a communication channel.
One communication channel in each direction, which can transmit an on/off signal is
required. The performance and security of this function is directly related to the
transmission channel speed and security against false or lost signals. Communication
speed, or minimum time delay, is always of utmost importance because the purpose for
using communication is to improve the tripping speed of the scheme.
To avoid false signals that could cause false tripping, it is necessary to pay attention to
the security of the communication channel. At the same time it is important to pay
attention to the communication channel dependability to ensure that proper signals are
communicated during power system faults, the time during which the protection
schemes must perform their tasks flawlessly.
The logic supports the following communications schemes:
• blocking schemes (blocking and delta blocking)
• permissive schemes (overreaching and underreaching)
• unblocking scheme and direct intertrip
1MRK 504 163-UUS A
Section 16
Scheme communication
Transformer protection RET670 2.2 ANSI 811
Application manual