SEF Directional Block
SEF Directional Blocking works the same way as EF and can use the same three methods to determine the direction of a SEF.
-
VZPS
-
Wattmetric
-
Ir Cos (Ø)
VZPS is the default option. The Decision setting determines the method used. Operating Quantities, Fault Angles, and default Characteristic Angles for each method are shown in the table below.
Table 80 Directional Blocking SEF Polarizing Methods
|
Polarizing Method (Decision) |
Operating Quantity |
Fault Angle |
Angle logged on Trip |
Default Characteristic Angle |
|---|---|---|---|---|
|
VZPS |
Earth Current (Ir) |
VZPS → IZPS |
VZPS → IZPS |
135° Configurable |
|
Wattmetric |
Residual Power VZPS x IZPS x Cos (FA) |
VZPS → IZPS |
(VZPS → IZPS) – CA (180°) |
180° Fixed |
|
Ir Cos (Ø) |
Active Earth Current IZPS x Cos (FA) |
VZPS → IZPS |
-VZPS → IZPS – CA (180°) |
180° Fixed |
Tripping direction options for SEFs regardless of the polarising method are:
-
Trip Forward
-
Trip Reverse
-
Trip Forward and Reverse (that is non directional)
SEF has a default setting current of 4 A and can be configured for between 1 A and 80 A.