ABB RED650 - Page 109

The master-slave configuration is achieved by setting parameter Operation in the
slaves to Off for Line differential protection function, and setting parameter
ChannelMode to On for the LDCMs in the slaves.
Test mode
SEMOD52415-48 v2
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
amplitude. 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
SEMOD52415-22 v2
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
38 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-US
Figure 38: Communication of current sampled values.
where:
x is the current sampling moment
Redundant communication channels
SEMOD52415-25 v4
With redundant communication channels, as shown in figure 39, both channels are
in operation continuously but with one of them favoured as a primary channel.
1MRK 505 394-UEN A Section 6
Differential protection
Line differential protection RED650 2.2 IEC 103
Technical manual