Critical Failure Relay #8; Virtual Outputs - GE 845 Instruction Manual

CHAPTER 4: SETPOINTS
Critical Failure Relay
#8

Virtual Outputs

845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
TYPE
Range: Self-Reset, Latched, Pulsed
Default: Pulsed
If Self-Reset is selected, the output relay is energized as long as the element is in
operating mode, and resets when the element drops out. If Latched is selected, the
output relay stays energized upon element dropout. The latched auxiliary outputs can
be reset by issuing a reset command. For Pulse selection, see SEAL-IN TIME (displayed
only if Type=Pulsed) on page 5-3.
OPERATION
Range: Non-Failsafe, Failsafe
Default: Non-Failsafe
Failsafe operation causes the output relay to be energized when the operand assigned
to the OPERATE AUX RLY # setting is low and de-energized when the same operand is
high. A failsafe relay also changes state (if not already activated by an operand driving
this output relay) when control power is removed from the 845. Conversely, a non-
failsafe relay is de-energized in its normal non-activated state and will not change state
when control power is removed from the 845 (if not already activated by a protection
element).
EVENTS
Range: Disabled, Enabled
Default: Enabled
The 845 relay is equipped with one output relay (# 8 - "Critical Failure Relay") for failsafe
indication. The Critical Failure Relay is a Form-C contact with one NO and one NC contact
(no control power). There are no user-programmable setpoints associated with this output
relay. The logic for this relay is shown below.
Figure 4-55: Critical Failure Relay 8 Scheme
The 845 relay is equipped with 32 virtual outputs that may be assigned for use via
FlexLogic. Virtual outputs not assigned for use are set to OFF (Logic 0).
A name can be assigned to each virtual output. Any change of state to a virtual output can
be logged as an event if programmed to do so. Virtual outputs are resolved in each
protection pass via the evaluation of FlexLogic equations.
For example, if Virtual Output 1 is the trip signal from FlexLogic and the trip relay is used to
signal events, the settings would be programmed as follows:
Virtual Output 1 NAME: Trip
Virtual Output 1 Events: Enabled
OUTPUTS
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