GE 850 Instruction Manual page 538

BUS TRANSFER
8–66
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.
INC 2 TRANSFORMER LOCKOUT
Range: Off, Any FlexLogic operand
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to initiate Transfer for substations with transformers and transformer fault lockout
devices. Typically, an auxiliary contact from the lockout relay (86T) is fed to one of the
850 contact inputs and set as "Source Transformer Lockout".
INC 2 SOURCE TRIP
Range: Off, Any FlexLogic operand
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to initiate Transfer for substations with an upstream circuit breaker equipped with
a trip signal (Device 94). The signal triggering the Transfer sequence can be originated
from the upstream protection. Typically, an auxiliary contact from the tripping device
(94) is fed to one of the 850 contact inputs and set as "Source Trip".
TIMED UV ON THIS SOURCE
Range: Off, Any FlexLogic operand
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to initiate Transfer for loss of source. Typically, a trip from "line" (source) Time
Undervoltage protection element is used to initiate Transfer.
BLOCK TRIP ON DOUBLE LOSS
Range: Enabled, Disabled
Default: Disabled
The setpoint selects the required scheme operation in the event of a simultaneous loss of
both Source 1 and Source 2. If it is desired to have both of the Incomers trip on Time
Undervoltage when this occurs, select "Disabled". If it is desired to prevent the Incomers
from tripping on Time Undervoltage when this occurs, select "Enabled". With either
selection, a transfer-initiated close of the bus tie breaker is not allowed.
INC 2 BKR CLOSED
Range: Off, Any FlexLogic operand
Default: Off
The setpoint selects the FlexLogic operand, digital input, virtual input or remote input
used to track a breaker-closed state. Typically, a 52a auxiliary breaker contact- or
breaker-closed state from the Breaker Detection control element is used to indicate the
close state of the breaker, thus preventing the two incoming power systems from being
connected in parallel, while at the same time permitting Transfer logic.
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: CONTROL