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

The following are the 51-n supported Curve Characteristic:
· DTL, IEC-NI, IEC-VI, IEC-EI, IEC-LTI, ANSI-MI, ANSI-VI, ANSI-EI
Table 3-2
Parameters Description
51-n Element 51-1 Block
51-n Setting Current Set point
51-n Char Characteristics
51-n Time
Time Multiplier
Mult
(other than DTL)
Delay
51-n Delay (Applicable only for
DTL)
51-n Min Minimum Operate
Operate Time
51-n Follower Follower DTL
51-n Reset Reset
3.3

Instantaneous Derived Earth Fault Protection (50N)

Earth current is derived by calculating the sum of the measured line currents.
Two instantaneous derived earth fault elements are provided in the 7SR45 self powered overcurrent and earth
fault relay.
50N-1, 50N-2
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 from:
Inhibit 50N-n
Figure 3-3
© 2017 Siemens Protection Devices Limited
Time Delayed Overcurrent Protection (51-n)
Default Value
Disabled
1xIn
DTL
1
5 s
0 s
0 s
0 s
A binary input.
Logic Diagram: Derived Instantaneous Earth Fault Element
7SR45 Description of Operation
Min Max Step Change
- - -
0.2xIn 2.0xIn 0.01
- - -
0.01 s 10 0.01
0 s 15 s 0.01
0 s 20 s 0.01
0 s 20 s 0.01
60, IEC/
0 s ANSI 1
DECAY
Chapter 1 Page 18 of 34