37G Undercurrent Earth Fault – Measured
Overview of Functions
Earth undercurrent protection is used to detect negligible current flow in the system earth connection.
Negligible current flow in the system earth connection is the normal system operate state. This check of negli-
gible current flow can be used in auto-isolation schemes.
Structure of the Function
The earth fault undercurrent 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 A37GPTUC* in IEC 61850.
The function monitors the primary system using the single phase current input e.g. CT4.
Blocking of the Stage
When a binary input configured as Inhibit 37G-n is operated, the picked up relevent function element will
reset.
Logic of the Function
[lo_7SR5_37Glogicdiagram, 1, en_US]
Figure 5-7 Logic Diagram: 37G Undercurrent Earth Fault – Measured
Application and Setting Notes
Parameter: Element
•
Default setting: Disabled
This setting is used to allow the element to be switched on and off if it is not required. A separate setting
is provided for each element. This setting can be used to select the number of elements required.
5.6
5.6.1
5.6.2
5.6.3
5.6.4
Protection and Automation Functions
5.6 37G Undercurrent Earth Fault – Measured
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 179
C53000-G7040-C014-1, Edition 11.2019
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