magnitude of polarizing voltage must be bigger than a minimum level defined bysetting VpolMin.Note that –V2 is used to determine the location of the fault. This ensures the requiredinversion of the polarizing voltage within the function.8.3.7.3 External polarizing for negative sequence function GUID-21930E81-1B40-4BA4-B1D8-3B365327AEF6 v1The individual steps within the protection can be set as non-directional. When thissetting is selected it is then possible via function binary input BLKx (where x indicatesthe relevant step within the protection) to provide external directional control (that is,torque control) by for example using one of the following functions if available in theIED:• Distance protection directional function• Negative sequence polarized general current and voltage multi purpose protectionfunction8.3.7.4 Internal negative sequence protection structure GUID-A6B9B3F1-A1FE-4653-A8AF-61FCCF19CE95 v1The protection is internally divided into the following parts:• Four negative sequence overcurrent steps• Directional supervision element for negative sequence overcurrent steps withintegrated directional comparison step for communication based negativesequence protection schemes (permissive or blocking)Each part is described separately in the following sections.8.3.7.5 Four negative sequence overcurrent stages GUID-D8ACB136-2BA6-4ADA-A096-5C38BD12DB72 v2Each overcurrent stage uses Operating Quantity I2 (negative sequence current) asmeasuring quantity. Every of the four overcurrent stage has the following built-infacilities:• Operating mode (Disabled/ Non-directional /Forward / Reverse). By thisparameter setting the operating mode of the stage is selected. Note that thedirectional decision (Forward/Reverse) is not made within the overcurrent stageitself. The direction of the fault is determined in common “Directional SupervisionElement” described in the next paragraph.• Negative sequence current pickup value.• Type of operating characteristic (Inverse or Definite Time). By this parametersetting it is possible to select Inverse or definite time delay for negative sequenceovercurrent function. Most of the standard IEC and ANSI inverse characteristics1MRK 511 408-UUS A Section 8Current protectionPhasor measurement unit RES670 2.2 ANSI 223Technical manual
