Pole-Discrepancy
Protection
PD scheme shall be provided for three
single-pole operating type CBs
The pole-discrepancy protection shall
use auxiliary contacts in the different phases, so that
a trip function shall be achieved for
discrepancy for both closing and opening operations of
the breaker. The pole-discrepancy
protection for CB shall be two-stage type. Both stage
Tripping relays shall be self-reset
type with hand-reset targets.
Two-Step
Pole-Discrepancy Protection
Upon occurrence of pole-discrepancy,
the time-delayed functions shall be provided in twosteps.
i. The first-step shall trip the
breaker with discrepancy. The time delay shall be sufficient
enough to avoid mal-functions due to
the differences in operating times of differentpoles
and shall have additional adequate
safety margin.
ii. The second-step shall be time
delayed so that if the attempt to trip the CB from firststep
in discordance protection is
successful, the function from second-step is inhibited.
If first-step is unsuccessful, all
adjacent CB's to the faulty breaker in the station shall be
tripped (not required for double bus
scheme to avoid major disturbance related with
tripping large number of CBs). Remote
CB tripping (if required) shall also be initiated.
iii. In addition to above, each step
shall have adequate contacts for annunciation, SOE and
SCADA functions shall be provided and
wired accordingly.
iv.Pole-Discrepancy transfer trip
receive relays 85PD-1 & 85PD-2 shall operate 94-1 & 94-2 of line
protection tripping relays (similar to BFP scheme).For 380KV & 230KV
system, Pole-Discrepancy receive relays 85PD-1 and 85PD-2 (PD only for three
single pole CBs only) shall be high security self-reset relays and mounted
in Set-1 & 2 protection panels to
operate 94-1 & 2 respectively of line (as applicable).
For system, Pole-Discrepancy receive
relays 85PD shall be high security self-reset
relays and mounted in Set-1 protection
panels to operate 94-1 & 94-2 of each (as
Applicable) ( PD transfer-trip scheme shall be via
totally independent channel).
PD stage-1
PD stage-2
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Can you suggest some literature for easy understanding of the num relay to scada connections via ethernet switches using various protocols ?
ReplyDeleteAlso there appears to be a dichotomy between pole discrepancy protection and enabling 1 pole auto reclose. Can you explain what is to be done ?
ReplyDelete