Instantaneous Sensitive Earth Fault Protection (50Sef); Figure 3.4-2 Logic Diagram: Sef Instantaneous Element - Siemens 7SR224 Description & Operation

(1) Description of Operation 7SR224
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
79 SEF Inst Trips: 50SEF-n
50SEF-n VTSAction: Inhibit
50SEF-n Element
Disabled
Enabled
AUTORECLOSE
Inhibit 50SEF-n
79 P/F Inst Trips
= 50SEF-n
&
79 P/F Prot'n Trip n
= Delayed
50SEF-n Dir.
Control
Non-Dir
Forward
Reverse
67SEF Fwd
67SEF Rev
Page 28 of 66
A binary or virtual input, or function key
When 'delayed' trips only are allowed in the auto-reclose
sequence (79 SEF Prot'n Trip n = Delayed).
Operation of the VT Supervision function.
&
50SEF-n Dir En
I (I )
4 SEF
50SEF-n VTS Action
Off
Non-Dir
Inhibit
VT Fail
&
1
&
Figure 3.4-2 Logic Diagram: SEF Instantaneous Element
50SEF-n Setting
50SEF-n Delay
c
>
& &
&
©2009 Siemens Protection Devices Limited
General Pickup
50SEF-n
1
50SEF-n Dir En