Differential Protection Analisys For Detection Of Ground Faults On the Generator Stator

The analysis of the restricted earth fault differential protection based on the implementation of a low impedance scheme that allows the protection of 3.5 kVA generator windings using the overcurrent relay in differential structure is presented. The configuration and testing of the 7SJ85 overcurrent protection relay is mainly focused on the built-in ANSI 87N, REF protection function. The configuration, parameterization and operation of the elements that make up the protection system are performed using OMICRON's CMC 356 and the 7SJ85 relay with their respective application software Test Universe and Digsi 5. The values used for the tests are based on the short-circuit analysis applying the IEC 60909 standard and the Complete method (equivalent to Thevenin), which were calculated and simulated in MatLab and DigSilent software respectively.

Automated summary

This article presents an analysis of the restricted earth fault differential protection using a low impedance scheme, which allows the protection of 3.5 kVA generator windings using an overcurrent relay in a differential structure. The focus is mainly on the configuration and testing of the 7SJ85 overcurrent protection relay with its built-in ANSI 87N, REF protection function. The protection system is configured, parameterized, and operated using OMICRON's CMC 356 and the 7SJ85 relay, along with their respective application software Test Universe and Digsi 5. The values used for testing are based on short-circuit analysis using the IEC 60909 standard and the Complete method.