ETL600 1KHW001489-EN ABB Switzerland Ltd
LINE 1
B PHASE
CF 1
CF 2
LINE 2
B PHASE
A
B
C
DNSD600
ETL600
A
B
C
DNSD600
ETL600
BFP Line 2
MP1 Line 1
MP2 Line 2
BFP Line 1
MP1 Line 2
MP2 Line 1
MP1: 1st main protection
MP2: 2nd main protection
BFP: breaker failure protection
+ overvoltage protection
+ compensator protection
CF: coupling filter
Fig. 3-38 Redundant protection of a dual-circuit line
The settings for the permissive main protection commands should as
given in section 3.6.5.1 and those for the direct tripping commands as
given in section 3.6.5.2.
3.6.5.6. Protecting Single-Circuit Lines
One or two signals - one for a permissive scheme and possibly a direct
transfer tripping signal - are usually sufficient when protecting lines in
the low to medium voltage range.
This task can be easily accomplished with the NSD600 using one relay
interface. Since the interface has four input and six output circuits,
further functions can be activated, e.g. start input, unblocking or
redundant command output. One of the commands is programmed to
be “permissive” with short transmission time and the other to “direct”.
The following recommended settings thus result:
Command output type: solid state
Application of command 1 permissive
Application of command 2 direct
Command prolongation for command 1: 10 ms
Command prolongation for command 2: 100 ms
Structure and Function November 2005 3-63
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