5-204 B30 BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS5The phase directional elements (one for each of phases A, B, and C) determine the phase current flow direction for steadystate and fault conditions and can be used to control the operation of the phase overcurrent elements via the BLOCK inputsof these elements.Figure 5-103: Phase A directional polarizationThis element is intended to apply a block signal to an overcurrent element to prevent an operation when current is flowingin a particular direction. The direction of current flow is determined by measuring the phase angle between the currentfrom the phase CTs and the line-line voltage from the VTs, based on the 90° or quadrature connection. If there is arequirement to supervise overcurrent elements for flows in opposite directions, such as can happen through a bus-tiebreaker, two phase directional elements should be programmed with opposite element characteristic angle (ECA) settings. PHASE DIR 1ECA: 30°Range: 0 to 359° in steps of 1 PHASE DIR POL V1THRESHOLD: 0.700 puRange: 0.004 to 3.000 pu in steps of 0.001 PHASE DIR 1 BLOCKWHEN V MEM EXP: NoRange: No, Yes PHASE DIR 1TARGET: Self-resetRange: Self-reset, Latched, Disabled PHASE DIR 1EVENTS: DisabledRange: Disabled, EnabledThe TARGET setting is not user-selectable and forced to "Disabled". If Targets are required from directionalelements, it can be achieved by assigning directional element output to a digital element, where targets selectioncan be used as required.
