Chapter 1 - 7SR45 Description of Operation
©2018 Siemens Protection Devices Limited Chapter 1 Page 24 of 48
Section 3: Protection Functions (50, 51, 50N, 51N, 50G,
51G, 50LC)
3.1 Instantaneous Overcurrent Protection (50)
Two Instantaneous overcurrent elements are provided in the 7SR45 Argus Relay.
50-1, 50-2
Each instantaneous element (50-n) has independent settings.
50-n Setting
for pick-up current and
50-n
Delay
definite time delay.
Operation of the instantaneous overcurrent elements can be inhibited by assigning binary inputs.
Inhibit 50-n
A binary input.
≥
1
Inhibit 50-n
50-n
Gn 50-n Setting
c
Gn 50-n
Enabled
Disabled
>
Gn 50-n Delay
>
>
IL1
IL2
IL3
Gn 50/51
Measurement
≥
1
General Pickup
&
Figure 3-1
Logic Diagram: Instantaneous Overcurrent Element
Table 3-1
Instantaneous Overcurrent Protection (50-n)
Parameters
Description
Default Value Min
Max
Step Change
Gn 50-n Element
50-n Block
Disabled
-
-
-
Gn 50-n Setting
Pick-up current
1
0.2xI
n
20xI
n
0.1
Gn 50-n Delay
Delay time
0
0 s
< 20 s
0.01
≥
20 s
< 100 s
0.1
≥
100 s
600 s
1
NOTE:
In a single-phase condition, it is recommended to use 50-n Setting 0.3xIn or higher.