Instantaneous Derived Earth Fault Protection (50N); Figure 3-3 Logic Diagram: Instantaneous Derived Earth Fault Element - Siemens 7SR45 Argus User Manual

3.3

Instantaneous Derived Earth Fault Protection (50N)

Two instantaneous derived earth fault elements are provided in the 7SR45 Argus Relay.
50N-1, 50N-2
Earth current is derived by calculating the vector sum of the measured phase currents.
Each instantaneous element has independent settings for pick-up current 50N-n Setting and a definite time delay
50N-n Delay.
Operation of the instantaneous derived earth fault elements can be inhibited by assigning binary inputs.
Inhibit 50N-n
Gn 50N- n Element
Disabled
Enabled
Inhibit 50N-n
IL1
∑
IL2
IL3
Figure 3-3
Table 3-4
Parameters Description
Gn 50N-n Element 50N-n Block
Gn 50N-n Setting Pick-up current
Gn 50N-n Delay Delay time
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A binary input.
&
Gn 50 N -n Setting
c
>
I
N
Logic Diagram: Instantaneous Derived Earth Fault Element
Instantaneous Derived Earth Fault Protection (50N-n)
Default Value
Disabled
1xIn
0
Chapter 1 - 7SR45 Description of Operation
General Pickup
Gn 50N - n Delay
50N-n
Min Max Step Change
- - -
0.2xI 20xI 0.1
n n
0 s < 20 s 0.01
≥ 20 s < 100 s 0.1
≥ 100 s 600 s 1
Chapter 1 Page 27 of 48