D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
505
D90
Plus
Line Distance Protection System
Chapter 10: Digital fault recorder
Digital fault recorder
The digital fault recorder captures detailed information regarding abnormal occurrences in
the power system. The information captured by the DFR is stored in the D90
Plus
in non-
volatile memory and can be accessed through the front panel interface. The DFR consists
of four primary functions.
•
A sequence of events recorder that provides a time-stamped record of the operation
of breakers, protection elements, and alarms. The recording of events is enabled on a
per-element basis.
•
A fault report that records fault type, magnitude and duration of the fault, and the
response of protection functions.
•
A transient recorder that records analog and digital signals for short duration events
at a high resolution.
•
A disturbance recorder that records analog and digital signals for long duration
events, such as power swings and voltage sags, at a resolution of one sample per
cycle.
Sequence of events recorder
This sequence of events recorder provides a time-stamped record of state changes of
signals monitored by the D90
Plus
. These signals include the state of circuit breakers and
disconnect switches, external alarms and indications, and any of the internal functions of
the IED. The D90
Plus
can store a total of 8192 events. Once this memory is filled, the oldest
events are overwritten. The events are time-stamped with an accuracy of 1 ms.
Most D90
Plus
elements contain an
Events
setting. When this setting is enabled, state
changes for FlexLogic™ operands associated with the element are written to the sequence
of events recorder. If this setting is disabled then state changes for the element are not
recorded.
Front panel operation
The sequence of events record can be accessed from the front panel through the digital
fault recorder (DFR) page. Using the navigations keys, the user can scroll or page through
the events list. Two cursors are provided for measurement of the time difference between
events.