7SR224 Argus Description of Operation
3.4.2 Instantaneous Sensitive Earth Fault Protection (50SEF)
Four elements are provided e.g. giving the option of using two elements set to forward and two to reverse.
Each instantaneous element has independent settings for pick-up current
50SEF-n Setting
and a follower time
delay
50SEF-n Delay
. The instantaneous elements have transient free operation.
For the directional elements the direction of operation can be set using
50SEF-n Dir. Control
setting. Directional
logic is provided independently for each 50SEF-n element.
Operation of the instantaneous earth fault elements can be inhibited from:
Inhibit 50SEF-n
A binary or virtual input, or function key
79 SEF Inst Trips: 50SEF-n
When ‘delayed’ trips only are allowed in the autoreclose sequence
(
79 SEF Prot’n Trip n
=
Delayed
).
50SEF-n VTSAction: Inhibit
Operation of the VT Supervision function.
Figure 3.4-2 Logic Diagram: SEF Instantaneous Element
©2010 Siemens Protection Devices Limited
Chapter 1 Page 27 of 70