Breaker Failure (Ansi 50Bf) - GE C70 Instruction Manual

GROUPED ELEMENTS
NEG SEQ DIR OC1 TYPE
Sequence" and "Zero Sequence." In some applications it is advantageous to use a directional negative-sequence
overcurrent function instead of a directional zero-sequence overcurrent function as inter-circuit mutual effects are
minimized.
NEG SEQ DIR OC1 POS-SEQ RESTRAINT
or 0.125 (in "Neg Sequence" mode) for backward compatibility with revisions 3.40 and earlier. Set it to zero to remove the
restraint. Set it higher if large system unbalances or poor CT performance are expected.
NEG SEQ DIR OC1 FWD ECA
characteristic angle in the reverse direction is the angle set for the forward direction shifted by 180°.
NEG SEQ DIR OC1 FWD LIMIT ANGLE
direction.
NEG SEQ DIR OC1 FWD PICKUP
threshold applies to zero-sequence or negative-sequence current based on the
specifying this setting, keep in mind that the design uses a positive-sequence restraint technique.
NEG SEQ DIR OC1 REV LIMIT ANGLE
direction.
NEG SEQ DIR OC1 REV PICKUP
threshold applies to zero-sequence or negative-sequence current based on the
selecting this setting, keep in mind that the design uses a positive-sequence restraint technique.
5

5.7.7 Breaker failure (ANSI 50BF)

SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  BREAKER FAILURE  BREAKER FAILURE 1(3)
 BREAKER FAILURE 1

5-224
— Selects the operating mode for the overcurrent unit of the element. The choices are "Neg
— Controls the positive-sequence restraint. Set it to 0.063 (in "Zero Sequence" mode)
— Select the element characteristic angle (ECA) for the forward direction. The element
— Defines a symmetrical limit angle (in both directions from the ECA) for the forward
— Defines the pickup level for the overcurrent unit in the forward direction. This pickup
— Defines a symmetrical limit angle (in both directions from the ECA) for the reverse
— Defines the pickup level for the overcurrent unit in the reverse direction. This pickup
Figure 5-115: Negative-sequence directional OC1 logic
BF1 FUNCTION:

Disabled
BF1 MODE:

3-Pole
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
setting. When
NEG SEQ DIR OC1 TYPE
setting. When
NEG SEQ DIR OC1 TYPE
Range: Disabled, Enabled
Range: 3-Pole, 1-Pole