GE D60 Instruction Manual page 595

CHAPTER 5: SETTINGS
In single-pole tripping applications, the scheme uses local fault type identification provided by the phase selector together
with information received from the remote terminal. The scheme generates output operands
TX4) that are used to transmit the signal to the remote terminal(s). Choices of communications channel include
HYBRID POTT
remote inputs/outputs and telecommunications interfaces. When used with telecommunications facilities, assign the
output operand to operate an output contact connected to key the transmitter at the interface. When used with
telecommunications facilities, assign the output operands to operate output contacts connected to assert the individual
bits at the interface.
To make the scheme fully operational as a stand-alone feature, the scheme output operands must be configured to
interface with other relay functions, output contacts in particular. Typically, you program the output operands to initiate a
trip, breaker fail, and autoreclose, and drive a user-programmable LED as per user application.
When used in conjunction with the trip output element, the scheme is pre-configured to initiate trip, breaker fail, and
single-pole autoreclose actions.
— This setting allows the user to assign any FlexLogic operand to block the scheme. Contact inputs from a
HYB POTT BLOCK
pilot cut-out switch are typically used for this purpose.
— If set to "Enabled", the scheme sends a permissive echo signal to the remote end(s) using a
HYB POTT PERMISSIVE ECHO
pre-programmed logic (see logic diagram below). If set to "Custom", the echo signal is sent if a condition selected via the
setting is satisfied. The echo is sent only once and then the logic locks out for the time specified by
HYB POTT ECHO COND
the setting. The duration of the echo pulse is settable as
ECHO LOCKOUT
protection elements (distance zone 2 or
— This setting specifies a user-selected echo condition and applies if the
HYB POTT ECHO COND
set to "Custom".
— If this setting is set to "Enabled", the scheme activates both the keying and operating paths using
HYB POTT WEAK INFEED
a pre-programmed weak infeed logic (see logic diagram below). If this setting is set to "Custom", the weak infeed condition
is to be specified by the user via the
— This setting specifies user-selected weak infeed condition and applies if the
HYB POTT W/I COND
set to "Custom".
— This setting enables the relay to cope with spurious received signals. Set the delay longer than
HYB POTT RX PICKUP DELAY
the longest spurious signal that can be received simultaneously with the zone 2 pickup. The selected delay increases the
TX
response time of the scheme.
— This setting defines a transient blocking mechanism embedded in the hybrid POTT scheme
TRANS BLOCK PICKUP DELAY
for coping with the exposure of both the over-reaching zone 2 and ground directional overcurrent function to current
reversal conditions.
The transient blocking logic applies to both operate (trip) and send (transmit) paths. Identifying the fault as a reverse fault
prevents the scheme from both operating and keying the channel. If the reverse fault condition prevails for
, the blocking operation is extended by the transient blocking timer for
PICKUP DELAY
riding through current reversal conditions.
However, if distance zone 1 picks up during the transient blocking condition, the blocking action is removed. This is to cope
with evolving faults when an external fault is followed by an internal fault. Without the zone 1 feedback, the trip is delayed
unnecessarily.
Do not set the
TRANS BLOCK PICKUP DELAY
extended blocking action can be established. Take into account the pickup time of the reverse-looking elements of the
scheme.
Do not set the delay too short, in order to avoid locking up a spurious reverse fault indication that can occur during internal
fault conditions.
— This setting defines a transient blocking mechanism embedded in the hybrid POTT scheme for
TRANS BLOCK RESET DELAY
coping with the exposure of the overreaching protection functions to current reversal conditions (see also the
).
PICKUP DELAY
D60 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
setting) inhibits the echo.
GND DIR O/C FWD
setting.
HYB POTT W/I COND
longer than the fastest possible trip time for faults on an adjacent line so that
(HYBRID POTT TX1
. Operation of the overreaching
ECHO DURATION
HYB POTT PERMISSIVE ECHO
HYB POTT WEAK INFEED
TRANS BLOCK RESET DELAY
CONTROL ELEMENTS
through
is
5
is
TRANS BLOCK
. This allows
TRANS BLOCK
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