ABB Relion 670 series, Technical Reference Manual, Page: 143 / 1232

The master-slave configuration is achieved by setting parameter Operation in the
slaves to Disabled for Line differential protection function, and setting parameter
ChannelMode to Enabled for the LDCMs in the slaves.
Test mode
Line differential protection function in one IED can be set in test mode. This can block
the trip outputs on that IED, and set the remote IEDs in a remote test mode, so that
injected currents can be echoed back phase shifted and with a settable magnitude. The
trip outputs in the remote IEDs can also be blocked automatically. For further
information, refer to the installation and commissioning manual.
Communication of current sampled values
The currents are sampled twenty times per power system cycle in the protection
terminals, but the communication exchange is made only once every 5 ms. This means
that at in each telegram sent, 5 consecutive current samples in a 50 Hz system and 6
consecutive current samples in a 60 Hz system (three phases each sampling instant) are
included. Figure
58 shows the principle.
0
Time
(ms) 5 10 15 20 25 30 35
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
Current
sample
telegram
sent
en05000290.vsd
IEC05000290 V1 EN
Figure 58: Communication of current sampled values.
where:
x
is the current sampling moment
Redundant communication channels
With redundant communication channels, as shown in figure 59 , both channels are in
operation continuously but with one of them favoured as a primary channel.
1MRK505222-UUS C
Section 5
Differential protection
137
Technical reference manual