GE 845 Instruction Manual page 249

CHAPTER 4: SETPOINTS
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845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Path:
Setpoints > Inputs > Virtual Inputs
FUNCTION
Range: Disabled, Enabled
Default: Disabled
If this setting is set to "Disabled," the input will be forced to OFF (logic 0) regardless of any
attempt to alter the input. If set to "Enabled," the input operates as shown on the logic
diagram below, and generates output FlexLogic operands in response to received input
signals and the applied settings.
NAME
Range: Up to 13 Alphanumeric Characters
Default: VI 1
An alphanumeric name may be assigned to a Virtual Input for diagnostic, setting, and
event recording purposes.
TYPE
Range: Latched, Self-reset
Default: Latched
There are two types of operation: self-reset and latched. If VIRTUAL INPUT x TYPE is "Self-
Reset," when the input signal transits from OFF to ON the output operand will be set to
ON for only one evaluation of the FlexLogic equations, then return to OFF. If set to
"Latched," the virtual input sets the state of the output operand to the same state as the
most recent received input.
The self-reset operating mode generates the output operand for a single evaluation of the
FlexLogic equations (i.e., a pulse of one protection pass). If the operand is to be used
anywhere other than internally in a FlexLogic equation, it will likely have to be lengthened
in time. A FlexLogic timer with a delayed reset time can perform this function.
EVENTS
Range: Enabled, Disabled
Default: Enabled
Figure 4-36: Virtual Inputs Scheme Logic
SETPOINTS
VIRTUAL INPUT 1
FUNCTION :
Disabled=0
Enabled =1
Virtual Input 1 to ON =1
Virtual Input 1 to OFF =0
SETPOINTS
VIRTUAL INPUT 1
TYPE:
Latched
Self-Reset
S
LATCH
FlexLogic Operands
Reset-
VI 1 ON
Dominant
R
INPUTS
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