Instantaneous Derived Earth Fault Protection (50N); Figure 3-6 Logic Diagram: Derived Instantaneous Earth Fault Element - Siemens 7SR10 Argus Series Manual

3.2.2

Instantaneous Derived Earth Fault Protection (50N)

Two instantaneous derived earth fault elements are provided in the 7SR1002/7SR1003 relay and four elements
are provided in the 7SR1004 relay.
Each instantaneous element has independent settings for pick-up current 50N-n Setting and a follower time
delay 50N-n Delay. The instantaneous elements have transient free operation.
Where directional elements are present the direction of operation can be set using 50N-n Dir. Control setting.
Directional logic is provided independently for each 50N-n element e.g. giving the option of using two elements
set to forward and two to reverse.
Operation of the instantaneous earth fault elements can be inhibited from:
Inhibit 50N-n
79 E/F Inst Trips: 50N-n
50N-n Inrush Action: Block
50N-n VTSAction: Inhibit
50N-n Inrush
Action
Off
Inhibit
81HBL2
AUTORECLOSE
79 P/F Inst Trips
= 50N-n
&
79 P/F Prot'n Trip n
= Delayed
50N-n Dir
Non-Dir
Forward
Reverse
67N Fwd
67N Rev
Figure 3-6
©2018 Siemens Protection Devices Limited
50N-1, 50N-2, (50N-3 & 50N-4 – 7SR1004)
A binary or virtual input.
When 'delayed' trips only are allowed in the auto-reclose sequence
(79 E/F Prot'n Trip n = Delayed).
Operation of the inrush current detector function.
Operation of the VT Supervision function.
50N-n Element
Disabled
Enabled
Inhibit 50N-n
&
50N-n Dir En
IL1
I
N
IL2
IL3
&
&
Logic Diagram: Derived Instantaneous Earth Fault Element
&
50N-n
Setting
c
>
If directional elements are not present this block is
50N-n VTS Action
omitted and the '50N-n Dir En' signal is set TRUE.
Off
Non Dir
Inhibit
&
VT Fail
≥1
7SR10 Description of Operation
General Pickup
50N-n Delay
50N-n
&
≥1
50N-n Dir En
&
Chapter 1 Page 31 of 77