Line Differential Protection; Identification; Application - ABB RELION 650 Series Applications Manual

1MRK 505 363-UEN A
6.2

Line differential protection

6.2.1

Identification

Function description
Line differential protection, 3 CT
Line differential protection, 6 CT
Line differential protection 3 CT
sets, with in-zone transformers, 2-3
Line differential protection 6 CT
sets, with in-zone transformers, 3-5
6.2.2

Application

Line differential protection can be applied on overhead lines and cables. It is an absolute
selective unit protection with a number of advantages. Coordination with other protections is
normally simple. All faults on the line, between the line bay CTs, can be cleared
instantaneously. The sensitivity can be made high, which is especially important for the ability
to detect high resistive earth faults. It is not influenced by possible voltage and/or current
inversion, associated with faults in series compensated networks. It is not influenced by fault
current reversal at earth faults on parallel lines. As it is phase-segregated, the identification of
faulted phases is inherent, and thus the application of single- or two-phase trip and auto-
reclosing can be made robust and reliable. Note that if an in-line or shunt power transformer is
included in the protected circuit, of the type Dy or Yd, then the protection cannot be phase-
segregated. Single-phase automatic re-closing will not be possible.
Line differential protection can be applied on multi-terminal lines with maximum three line
ends. Depending on the actual network, reliable fault clearance can often be difficult to achieve
with conventional distance protection schemes in these types of applications.
Application manual
sets, 2-3 line ends
sets, 3-5 line ends
line ends
line ends
Line differential logic
It is recommended to use the same firmware version as well as hardware
version for a specific line differential scheme.
IEC 61850 IEC 60617
identification identification
3Id/I>
L3CPDIF
SYMBOL-HH V1 EN-US
3Id/I>
L6CPDIF
SYMBOL-HH V1 EN-US
3Id/I>
LT3CPDIF
SYMBOL-HH V1 EN-US
3Id/I>
LT6CPDIF
SYMBOL-HH V1 EN-US
LDLPSCH -
Section 6
Differential protection
ANSI/IEEE C37.2
device number
87L
87L
87LT
87LT
87L
IP13934-1 v1
M14844-1 v4
IP14947-1 v1
M12022-3 v6
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