46 Negative-Sequence Overcurrent Protection; Overview Of Functions; Structure Of The Function - Siemens Reyrolle 7SR5 Manual

Protection and Automation Functions

5.7 46 Negative-Sequence Overcurrent Protection

5.7 46 Negative-Sequence Overcurrent Protection

Overview of Functions

5.7.1
Negative sequence overcurrent protection is used to:
•
Detect 1-phase or 2-phase short circuits in the electrical power system
•
Protect electric machines during excessive unbalanced load
•
Alarm for unbalanced system load conditions
5.7.2

Structure of the Function

The negative phase sequence overcurrent protection function has group dependent settings. These settings
can be different in each settings group – group numbers (Gn) 1 to 4.
This function corresponds to the logical node A46DTPTOC* and A46ITPTOC* in IEC 61850.
The function monitors the primary system using the 3 phase current inputs e.g. CT1/2/3. The negative
sequence phase (NPS) component of current (I
The function has 2 element types:
•
Definite-time negative-sequence protection (46DT)
•
Inverse-time negative-sequence protection (46IT)
Blocking of the Stage
When a binary input configured as Inhibit 46DT-n or Inhibit 46IT-n is operated, the associated func-
tion element will reset.
180
) is derived from the 3 phase currents.
2
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019