ABB ETL600 - Page 96

ABB Switzerland Ltd 1KHW001489-EN ETL600
The corresponding settings and further programming instructions are
to be found in section 5.3.3.
Important single-circuit lines (400 kV to 800 kV) are always equipped
with duplicated main protection, breaker failure protection and perhaps
a generator shutdown / load shedding facility. Two ETL600 links, each
with a four-command NSD600, are then arranged in a fully duplicated
teleprotection scheme according to Fig. 3-39.
Such an arrangement requires the transmission of three or four
transfer tripping signals, one permissive signal for each of the main
protections, a direct transfer tripping signal for the breaker failure
scheme and perhaps a direct transfer tripping signal for the generator
shutdown / load shedding facility.
In this case the NSD600 is again equipped with one relay interface at
least. Additional interfaces may be plugged into reserved slots if more
functions are to be used.
The teleprotection interface type G4AI is used for the two main
protection commands (A, B), and for the direct tripping commands (C,
D). The settings for the permissive commands should be those given
in section 3.6.5.1 and for the direct tripping command those given in
section 3.6.5.2.
A PHASE
CF 1
CF 2
B PHASE
A
B
C
DNSD600
ETL600
A
B
C
DNSD600
ETL600
MP1
MP2
GSD/LS
MP1: 1st main protection
MP2: 2nd main protection
BFP: breaker failure protection
+ overvoltage protection
+ compensator protection
BFP
GSD: generator shut down
LS: load shedding
CF: coupling filter
Fig. 3-39 Duplicated protection for a single-circuit line
3-64 November 2005 Structure and Function