Instantaneous Derived Earth Fault Protection (50N) - Siemens Reyrolle 7SR45 Argus Device Manual

Functions

3.4 Instantaneous Derived Earth Fault Protection (50N)

3.4

Instantaneous Derived Earth Fault Protection (50N)

Overview of the Function (50N)
The Instantaneous derived earth fault protection is used to provide:
•
Short-circuit detection in electrical equipment
•
High-speed protection where appropriate to its location in the power system network and/or network
impedances
•
Backup or emergency protection in addition to other protection functions or devices
•
Coordinated operation with other devices using time graded settings
Structure of the Function (50N)
The instantaneous earth fault protection function element has group-dependent settings. These settings can
be different in each settings group – group numbers (Gn) 1 and 2.
The function monitors the primary system earth current by calculating the sum of the 3-phase CT inputs for
example CT1/2/3.
The basic instantaneous derived earth fault function (50N) is characterized by the following:
•
Current measurement is based on the fundamental current.
•
Elements operate with a Definite Time Lag (DTL) characteristic.
•
LED operations are provided for earth fault. A general pickup and 50N-n output are also provided.
Logic of the Function (50N-n)
[lo_7sr45_50N_TimeDelayedDerivedEFFn, 2, en_US]
Application and Settings Notes
Gn 50N-n Element
Default setting: Disabled
50 Reyrolle, 7SR45, Device Manual
C53000-G7040-C101-2, Edition 09.2020