GE L90 Instruction Manual page 383

5 SETTINGS
• POTT SEAL-IN DELAY: The output FlexLogic™ operand (
A seal-in time delay is applied to this operand for coping with noisy communication channels. This setting specifies a
minimum guaranteed duration of the
• GND DIR O/C FWD: This setting selectes the FlexLogic™ operand (if any) of a protection element used in addition to
zone 2 for identifying faults on the protected line, and thus, for keying the communication channel and initiating opera-
tion of the scheme. Good directional integrity is the key requirement for an over-reaching forward-looking protection
element used as
GND DIR O/C FWD
the user to combine responses of various protection elements, or to apply extra conditions through FlexLogic™ equa-
tions, this extra signal is primarily meant to be the output operand from either the negative-sequence directional over-
current or neutral directional overcurrent elements. Both of these elements have separate forward and reverse output
operands. The forward indication should be used (
• POTT RX: This setting enables the user to select the FlexLogic™ operand that represents the receive signal (
the scheme. Typically an input contact interfacing with a signaling system is used. Other choices include remote inputs
and FlexLogic™ equations. The POTT transmit signal (
tem by assigning the output FlexLogic™ operand (
another choice.
The output operand from the scheme (
tacts in particular, in order to make the scheme fully operational. Typically, the output operand should be programmed
to initiate a trip, breaker fail, and autoreclose, and drive a user-programmable LED as per user application.
SETTING
POTT SCHEME
FUNCTION:
Disabled = 0
Enabled = 1
FLEXLOGIC OPERANDS
AND
PH DIST Z2 PKP
OR
GND DIST Z2 PKP
SETTING
AND
GND DIR O/C FWD:
Off = 0
FLEXLOGIC OPERAND
AND
POTT RX:
Off = 0
FLEXLOGIC OPERAND
LINE PICKUP LEO PKP
SETTING
POTT PERMISSIVE ECHO:
Disabled = 0
Enabled = 1
GE Multilin
POTT OP
pulse.
POTT OP
. Even though any FlexLogic™ operand could be used as
NEG SEQ DIR OC1 FWD
) should be appropriately interfaced with the signaling sys-
TX
) to an output contact. The remote output mechanism is
POTT TX
) must be configured to interface with other relay functions, output con-
POTT OP
SETTINGS
POTT RX PICKUP
DELAY:
t
PKP
0
SETTINGS
TRANS BLOCK PICKUP
AND
DELAY:
TRANS BLOCK RESET
DELAY:
t
PKP
t
RST
SETTINGS
LINE END OPEN PICKUP
DELAY:
t
PKP
0
AND
Figure 5–137: POTT SCHEME LOGIC
L90 Line Current Differential System
5.7 CONTROL ELEMENTS
) is produced according to the POTT scheme logic.
GND DIR O/C FWD
or
NEUTRAL DIR OC1 FWD
AND
SETTINGS
POTT SEAL-IN
DELAY:
0
OR
t
RST
AND
SETTINGS
ECHO DURATION:
ECHO LOCKOUT:
Echo duration and lockout logic
allowing
).
) for
RX
5
FLEXLOGIC OPERAND
POTT OP
FLEXLOGIC OPERAND
OR POTT TX
837014A9.CDR
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