652 D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
SINGLE-POLE TRIPPING CHAPTER 15: THEORY OF OPERATION
Figure 560: Dynamic reach, high-current internal fault
Single-pole tripping
Single-pole operations make use of many D90
Plus
features. At a minimum, the trip output,
recloser, breaker control, open pole detector, and phase selector must be fully
programmed and in-service, and either protection elements or digital inputs representing
fault detection must be available for successful operation. When single pole trip-and-
reclose is required, overall control within the relay is performed by the trip output element.
This element includes interfaces with pilot-aided schemes, the line pickup, breaker control,
and breaker failure elements. Single-pole operations are based on use of the phase
selector to identify the type of the fault, to eliminate incorrect fault identification that can
be made by distance elements in some circumstances and to provide trip initiation from
elements that are not capable of any fault type identification, such as high-set negative-
sequence directional overcurrent element. The scheme also is designed to make use of the
advantages provided by communications channels with multiple-bit capacities for fault
identification.
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