Instantaneous Measured Earth Fault Protection (50G); Figure 3-5 Logic Diagram: Instantaneous Measured Earth-Fault Element - Siemens 7SR45 Argus User Manual

The following are the 51N-n supported curve characteristic:
·
DTL, IEC-NI, IEC-VI, IEC-EI, IEC-LTI, ANSI-MI, ANSI-VI, ANSI-EI
Table 3-4
Parameters Description
51N-n
51N-n Block
Element
51N-n Setting Current Set point
51N-n Char Characteristics
Time Multiplier
51N-n Time
Mult
(other than DTL)
Delay
51N-n Delay (Applicable only for
DTL)
51N-n Min Minimum Operate
Operate Time
51N-n
Follower DTL
Follower DTL
51N-n Reset Reset
3.5

Instantaneous Measured Earth Fault Protection (50G)

The earth current is measured directly via a dedicated current analogue input, I
Two instantaneous measured earth fault elements are provided in the 7SR45 self powered overcurrent and earth
fault relay.
50G-1, 50G-2
Each instantaneous element has independent settings for pick-up current 50G-n Setting and a definite time delay
50G-n Delay.
Operation of the instantaneous measured earth fault elements can be inhibited from:
Inhibit 50G-n
Figure 3-5
© 2017 Siemens Protection Devices Limited
Time Delayed Derived Earth Fault Protection (51N-n)
Default Value Min
Disabled -
0.5XIn 0.1xIn
DTL -
1 0.01
5 s 0 s
0 s 0 s
0 s 0 s
0 s 0 s
A binary input
Logic Diagram: Instantaneous Measured Earth-fault Element
7SR45 Description of Operation
Max Step Change
- -
0.8xIn 0.01
- -
10 0.01
15 s 0.01
20 s 0.01
20 s 0.01
60, IEC/
ANSI 1
DECAY
.
N
Chapter 1 Page 20 of 34