GE D60 Instruction Manual page 291

5 SETTINGS
• TRANS BLOCK RESET DELAY: This setting defines a transient blocking mechanism embedded in the Hybrid POTT
scheme for coping with the exposure of the overreaching protection functions to current reversal conditions (see also
the
TRANS BLOCK PICKUP DELAY
This delay should be selected long enough to cope with transient conditions including not only current reversals but
also spurious negative- and zero-sequence currents occurring during breaker operations (in the case when Neutral
Directional or Negative-Sequence Directional overcurrent functions are used). The breaker failure time of the sur-
rounding protection systems within the reach of the ground directional function used by the Hybrid POTT scheme
should be considered to make sure that the ground directional function is not jeopardized during delayed breaker oper-
ations.
• ECHO DURATION: This setting defines the guaranteed and exact duration of the echo pulse. The duration is not
dependent on the duration and shape of received RX signals. This setting enables the relay to avoid a permanent lock-
up of the transmit/receive loop.
• ECHO LOCKOUT: This setting defines the lockout period for the echo logic after sending the echo pulse. This enables
the relay to avoid oscillations of the echo pulses during an autoreclosure dead-time after clearing an internal fault.
• HYB POTT SEAL-IN DELAY: The output FlexLogic™ operand (
POTT scheme logic. The
As this operand runs the trip table of the Hybrid POTT scheme, the trip operands
sealed-in for the same period of time.
• GND DIR O/C FWD: This setting defines the FlexLogic™ operand (if any) of a protection element that is used in addi-
tion to Zone 2 for identifying faults on the protected line, and thus, for keying the communication channel and initiating
operation of the scheme (both through the transient blocking logic). Good directional integrity is the key requirement for
an over-reaching forward-looking protection element used as
Even though any FlexLogic™ operand could be used as
various protection elements or to apply extra conditions through FlexLogic™ equations, this extra signal is primarily
meant to be the output operand from either the Negative-Sequence Directional or Neutral Directional Overcurrent ele-
ments. Both these elements have separate forward (
should be used (
NEG SEQ DIR OC1 FWD
The selected protection element (or elements in combination) should be coordinated with the selection of
. For all the forward external faults seen by an element used as
REV
looking element used as
• GND DIR O/C REV: This setting defines the FlexLogic™ operand (if any) of a protection element used in addition to
Zone 4 for identifying reverse faults, and thus, for stopping the transmit signal and initiating the transient blocking timer.
Good directional integrity is the key requirement for a reverse-looking protection element used as
Even though any FlexLogic™ operand could be used as
various protection elements or to apply extra conditions through FlexLogic™ equations, this extra signal is primarily
meant to be the output operand from either the Negative Sequence Directional or Neutral Directional Overcurrent ele-
ment. Both these elements have separate forward (
should be used (
NEG SEQ DIR OC1 REV
The selected protection element (or elements in combination) should be coordinated with the selection of
. For all the forward external faults seen by an element used as
FWD
reverse-looking element used as
• HYB POTT NO OF COMM BITS: This setting specifies the number of bits of the communications channel available for
the scheme. The transmit codes and trip table of the Hybrid POTT scheme are the same as those for the permissive
under-reaching transfer trip scheme. Please refer to the description of the PUTT scheme for more information.
• HYB POTT RX1 through HYB POTT RX4: These settings allow the user to select the FlexLogic™ operands that rep-
resent the receive signals for the scheme. Typically input contacts interfacing with a signaling system are used. In sin-
gle-bit applications, HYB POTT RX1 must be used. In two-bit applications,
used. In four-bit applications,
GE Multilin
).
defines a minimum guaranteed duration of the
HYB POTT SEAL-IN DELAY
FWD
or
NEUTRAL DIR OC1 FWD
at the other end should pickup and provide a blocking signal.
GND DIR O/C REV
FWD
or
NEUTRAL DIR OC1 REV
at the other end should pickup and provide a blocking signal.
GND DIR O/C REV
,
HYB POTT RX1 HYB POTT RX2
D60 Line Distance Relay
) is produced according to the Hybrid
HYB POTT OP
HYB POTT TRIP A
.
GND DIR O/C FWD
enabling the user to combine responses of
GND DIR O/C FWD
) and reverse ( ) output operands. The forward indication
REV
).
at one end of the line, the reverse-
GND DIR O/C FWD
enabling the user to combine responses of
GND DIR O/C REV
) and reverse ( ) output operands. The reverse indication
REV
).
GND DIR O/C FWD
HYB POTT RX1
, , and
HYB POTT RX3 HYB POTT RX4
5.6 CONTROL ELEMENTS
pulse.
HYB POTT OP
, , and are
B C 3P
GND DIR O/C
.
GND DIR O/C REV
GND DIR O/C
at one end of the line, the
and must be
HYB POTT RX2
must be used.
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