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

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