ABB Relion 670 series, Technical Reference Manual

Page: 130 / 1232

A line charging current compensation provides increased sensitivity of Line differential
protection.
5.1.1.2 Line differential protection 3 or 6 CT sets, with in-zone transformers
LT3CPDIF, LT6CPDIF
Two two-winding power transformers, or one three-winding power transformer, can be
included in the line differential protection zone. Both two- and three-winding
transformers are correctly represented with phase shift compensations made in the
algorithm. The function includes 2
nd
and 5
th
harmonic restraint and zero-sequence
current elimination.
IED IED
Protected zone
Communication Channel
IED
Communication Channel Communication Channel
ANSI0500042_2_en.vsd
ANSI05000042 V2 EN
Figure 48: Example of application on a three-terminal line with a power
transformer in the protection zone
5.1.1.3 Analog signal transfer for line differential protection
The line differential communication can be arranged as a master-master system or a
master-slave system alternatively. In the former, current samples are exchanged
between all IEDs, and an evaluation is made in each IED. This means that a 64 kbit/s
Section 5
1MRK505222-UUS C
Differential protection
124
Technical reference manual