CHAPTER 4: INTERFACES HARDWARE INTERFACE
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–3
–The S6 TESTING SIMULATION SIMULATION SETUP SIMULATION FUNCTION
setpoint is set to “Prefault Mode”, “Fault Mode”, or “Playback Mode”.
– Factory service mode is enabled.
• DIFFERENTIAL BLOCKED: The Differential Blocked LED is on when the restrained
differential protection feature is enabled but is being blocked from operating by any of
the harmonic inhibit features. The indicator is on if the harmonic inhibit element is
blocking any phase (see Harmonic inhibit on page 5–52).
• LOCAL: The Local LED indicator is on when the 745 is in local mode, i.e. the front panel
RESET key is operational.
• MESSAGE: The Message LED indicator is on when any element has picked up,
operated, or is now in a latched state waiting to be reset. With this indicator on, the
front panel display is sequentially displaying information about each element that has
detected an abnormal condition.
4.1.4.2 System Status Indicators
• TRANSFORMER DE-ENERGIZED: The Transformer De-Energized LED indicator is on
when the energization inhibit feature has detected that the transformer is de-
energized. The indicator is on if the Energization Inhibit feature is detecting the
transformer as de-energized
• TRANSFORMER OVERLOAD: The Transformer Overload LED indicator is on when the
Transformer Overload element has operated.
• LOAD-LIMIT REDUCED: The Load-Limit Reduced LED indicator is on when the
adaptive harmonic factor correction feature is detecting enough harmonic content to
reduce the load rating of the transformer. The indicator is on if
S2 SYSTEM SETUP
HARMONICS HARMONIC DERATING ESTIMATION is “Enabled” and the harmonic
derating function is below 0.96.
• SETPOINT GROUP 1(4): These indicators reflect the currently active setpoint group.
The indicators flash when the corresponding setpoint group is being edited.
4.1.4.3 Output Status Indicators
• TRIP: The Trip LED is on when any output relay selected to be of the Trip type has
operated.
• ALARM: The Alarm LED is on when any output relay selected to be of the Alarm type
has operated.
• PICKUP: The Pickup LED is on when any element has picked up. With this indicator on,
the front panel display is sequentially displaying information about each element that
has picked up.
• PHASE A (C): The Phase A(C) LEDs are on when phase A(C) is involved in the condition
detected by any element that has picked up, operated, or is now in a latched state
waiting to be reset.
• Ground: The Ground LED is on when ground is involved in the condition detected by
any element that has picked up, operated, or is now in a latched state waiting to be
reset.
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