ABB REL300 Instruction Manual page 69

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3.21 LOGIC FOR RB ON BF SQUELCH
(Setting BFRB)
For a pilot system, the BFI signal can be used to stop (for a blocking system) or start (for per-
missive schemes) the carrier channel to allow far end line terminals to trip in the event a breaker
close to an external fault fails to open. The problem is how to inhibit reclosing on those termi-
nals, to limit damage.
REL300 solves this problem at the far end terminals by the Reclose Block on Breaker Failure
Squelch logic in the RI/RB software. When the breaker fails to trip, the BFI logic squelches the
channel to continuous permissive signal, or stops the blocking signal. This is done after some
time delay. The relay at the far end, having sensed the external fault in the forward direction,
sees the permissive signal (or stoppage of blocking signal) much later than it would for a normal
pilot trip operation initiated by relay forward-looking elements at the end closer to the fault. This
time delay is used to differentiate between a faster normal pilot trip and the slower problem-
related pilot trip initiated by BFI, and to block reclosing in the latter case.
This logic is shown in Figure 3-19 (page 3-41, which includes AND-61A and a 132/0 ms timer.
The logic at the far end terminal will initiate RB (and inhibit RI) at 132 ms (about eight cycles)
after the fault is detected by the overreaching PLTP or PLTG element, if the pilot is enabled
and the TRSL signal is received on any three-pole trip operation. If the fault is cleared before
the 132 ms expiration of the timer, normal reclosing will occur.
3.22 OUT-OF-STEP (
3.23 OPTIONAL SINGLE-POLE TRIP (SPT) LOGIC AND OUTPUTS (Refer to Section 3.4.18) Without Pro-
grammable Output Contact Option
3.24 OPTIONAL PROGRAMMABLE OUTPUT CONTACTS WITHOUT SPT OPTION
The optional programmable output contact module consists of 8 relays, 4 with heavy duty NO
contacts (OC1 to OC4) and 4 with standard contacts (OC5 to OC8) with jumper selection for
NO or NC outputs. Contacts OC4 and OC8 provide timers for delay pickup and/or delay drop-
out. The ranges of timers are 0 to 5 seconds in 0.01 second steps with an error of ± 1 cycle.
Every Contact (OC1 to OC8) can be programmed independently based on one or all of the 30
pre-assigned signals with AND/OR/NOT logic combination. These 30 signals are listed in Table
3-4, page 3-53 and Figure 3-33 (page 3-50). All 8 output settings can be performed only
through remote WRELCOM
In addition to the foregoing features and options, the REL300 Pilot Zone system includes many
of the same special functions as the Non-Pilot system, i.e.:
eration, it sends no echo signal to the strong end. Both the strong/weak ends will not
trip on this external fault.
Weak end trip on internal fault
The output of AND-65 (start echo keying) together with no output from OR-40 (pilot
trip relays), and with output from OR-44 (low voltage condition) will satisfy AND-66;
weakfeed trip will be performed after 50 ms via OR-2. The timer delay is for coordi-
nation because the voltage trip units are non-directional.
OS
) LOGIC (Refer to Section 3.4.17, page 3-13)
®
communication (RCP).
I.L. 40-385.7
3-25