332
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS
CHAPTER 7: PROTECTION
Figure 270: VT fuse failure scheme logic
Open pole detector
The open pole detector is intended to identify an open pole of the line circuit breaker. The
scheme monitors the breakers 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
BREAKER 1 ?A CLSD
through
BREAKER 1 ?C CLSD
and
BREAKER 1 OOS
, and are used by the open pole feature (these operands are also available
for 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, breaker 2 should be enabled and the
breaker 2
Out of Service
setting should be “On”.
Select the
Settings > Protection > Control > Open Pole
menu item to access the open
pole detector settings.
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