MC20-CEI
Doc. N°
MO-0431-ING
Microelettrica Scientifica S.p.A. - Copyright 2009
FW 1080.36.03.X
Date 18.11.2011
Rev.
3
Pag. 18
of 35
4. Logic Blocking of Functions
4.1 – Blocking output
The instantaneous element of each of the protection functions can be programmed to control one of the Output
Relays.
This relay picks-up as soon as the input quantity exceeds the set trip level of the Protection Function and it
automatically resets when the input quantity drops below the function reset level (
≈
95% of the trip level) or, in
any case as soon as the time delay (
tBF
) of the Breaker Failure function is expired.
This instantaneous output can be used to activate the Blocking Input of another Protection Relay to implement a
logic selectivity systems. As above explained, in case of Breaker Failure, the blocking output is released and the
back-up protection enabled.
4.2 – Blocking Input
The blocking action of any protection functions can be controlled by activating the digital input:
-
D1 (BI = Enable) (functions I>, I>>, I>>>, Io>, Io>>, 67S1, 67S2)
5. Output Relays
Three user programmable Output Relays are normally available R1, R2, R3.
Each of them can be programmed to be controlled by any element (instantaneous or time delayed) of any of the
Relay Functions including Breaker Failure ("
AnIn
" (BF)) and Internal Relay Fault (
IRF
).
Each output relay can also be programmed to operate “
OPEN
” and “
CLOSE
” control of the C/B either by the Relay
Keyboard or via the serial communication bus
Moreover, the operation of each of the output relays can be programmed to be either Normally Deenergized
(energized on tripping of the controlling Functional Element) or Normally Energized (Deenergized on tripping of the
controlling Functional Element)
