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CHAPTER 4: SETPOINTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
DELAY SELECT TO TRIP
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000 s
The setting provides the selection of a time delay to be applied to the 850 Trip output
relay. The following conditions must be met to start the "Delay Select To Trip" setpoint:
–
Incomer 1 breaker connected
–
Incomer 2 breaker connected and closed
–
Tie-breaker connected and closed
–
Selected to Trip input set to Incomer 1 breaker
–
Transfer scheme not blocked.
INC 2 BKR CONNECTED & CLOSED
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to provide permission for Transfer if Incomer breaker 1 is connected and closed.
This setpoint also provides a condition for the "Selected to Trip" breaker logic.
TIE BKR CONNECTED & CLOSED
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to provide a condition for "Selected to Trip" breaker logic if the bus tie breaker is
racked-in (connected) and closed.
TIE BKR CONNECTED
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to provide permission for Transfer if Bus Tie breaker is racked-in (connected).
The Transfer Scheme can be applied to any one of the following systems:
–
Substations with a source transformer and transformer fault detection signal
(Device 86T). In addition to the local 850 relays, the signal triggering the transfer
sequence can originate from the protection of the upstream transformers. An
auxiliary contact from the tripping device (86T) is fed to one of the 850 inputs,
which is programmed as "Source Transformer Lockout".
–
Substations with an upstream circuit breaker equipped with a trip signal (Device
94). In addition to the local 850 relays, the signal triggering the transfer sequence
can be originated from the upstream protection. An auxiliary contact from the
tripping device (94) is fed to one of the 850 inputs, which is programmed as
"Source Trip".
–
Substations with a source transformer and transformer fault detection signal
(Device 86T) and with an upstream circuit breaker equipped with a trip signal
(Device 94). In addition to the local 850 relays, the signal triggering the transfer
sequence can be originated from the protection of the upstream transformers or
from the upstream protection. Auxiliary contacts from the tripping devices (86T
and 94) are fed to the 850 inputs which are programmed as "Source Transformer
Lockout" and "Source Trip".
–
Substations with no signaling from upstream equipment. The initiating signal is
generated by one of the two 850 relays protecting the Incomers. Typically the
Time Undervoltage Protection Function trip is the initiating signal.
The only differences in implementing the Transfer Scheme (among the configurations
presented above) are by connecting input signals to the relay when available.
CONTROL
4–333
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