ABB Relion 670 Series Applications Manual page 387

1MRK 511 358-UUS A
Section 14
14.1 Scheme communication logic for distance or overcurrent
protection ZCPSCH(85)
14.1.1 Identification
Function description
Scheme communication logic for
distance or overcurrent protection
14.1.2 Application
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
communication channels.
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. For this reason special channels are used for this
purpose. When power line carrier is used for communication, these special channels are strongly
recommended due to the communication disturbance caused by the primary fault.
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 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.
A permissive scheme is inherently faster and has better security against false tripping than a
blocking scheme. On the other hand, permissive scheme depends on a received CR signal for a fast
trip, so its dependability is lower than that of a blocking scheme.
Application manual
Scheme communication
IEC 61850
identification
ZCPSCH
IEC 60617 ANSI/IEEE C37.2
identification device number
- 85
Section 14
Scheme communication
IP15749-1 v3
M14854-1 v4
IP15020-1 v1
M16866-3 v4
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