Open Pole Detector - GE D90 Plus Instruction Manual

CHAPTER 7: PROTECTION

Open pole detector

PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
The open pole detector identifies an open pole of the line circuit breaker. It monitors the
breaker's auxiliary contacts, current in the circuit, and voltage (optional) on the line. The
scheme generates output operands used to block the phase selector and some specific
protection elements, thus preventing maloperation during the dead time of a single pole
autoreclose cycle or any other open pole conditions.
The scheme declares an open pole at the moment a single-pole trip is issued.
In two-breaker and breaker-and-a-half applications, an open pole condition is declared
when any of the following occur:
• Both breakers have an open pole on the same phase
• The current on the line drops below a threshold
• The current and voltage on the line drop below a threshold
The open pole feature uses signals defined by the breaker control, distance, and trip output
features. Voltage supervision can be used only with wye VTs on the line-side of the
breakers.
For convenience, the position of the breaker poles defined in the breaker control feature
and available as FlexLogic operands
are used by the open pole feature (these operands are also available for
BREAKER 1 OOS
breaker 2). For correct operation of the open pole detector, the breaker control, trip output,
and single-pole autoreclose features must be enabled and properly configured. When
used in configuration with only one breaker, enable breaker 2 and set the breaker 2
setting to "On."
Service
Select the Settings > Protection > Control > Open Pole menu to access the open pole
detector settings.
Figure 274: VT fuse failure logic
through
BREAKER 1 ?A CLSD
CONTROL ELEMENTS
and
BREAKER 1 ?C CLSD
Out of
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