Time Delayed Derived Earth Fault Protection (51N); Figure 3-4 Logic Diagram: Derived Time Delayed Earth Fault Protection - Siemens 7SR45 Argus User Manual

Table 3-3
Parameters Description
50N-n
50N-n Block
Element
50N-n Setting Current Set point
50N-n Delay Delay time
3.4

Time Delayed Derived Earth Fault Protection (51N)

One time delayed derived earth fault element is provided in the 7SR45 self powered overcurrent and earth fault
relay.
51N-1
51N-n Setting sets the pick-up current level.
A number of shaped characteristics are provided. An inverse definite minimum time (IDMT) characteristic is
selected from IEC and ANSI using 51N-n Char. A time multiplier is applied to the characteristic curves using the
51N-n Time Mult setting. Alternatively, a definite time lag delay (DTL) can be chosen using 51N-n Char. When
definite time lag (DTL) is selected the time multiplier is not applied and the 51N-n Delay (DTL) setting is used
instead.
The 51N-n Reset setting can apply a definite time delayed reset, or when the operation is configured as an IEC
or ANSI if the reset is selected as IEC/ANSI (DECAY) reset, the associated reset curve will be used.
A minimum operate time for the characteristic can be set using the 51N-n MinOperate setting.
A fixed additional operate time can be added to the characteristic using the 51N-n Follower setting.
Operation of the time delayed derived earth fault elements can be inhibited by assigning binary inputs.
Inhibit 51N-n
Figure 3-4
© 2017 Siemens Protection Devices Limited
Instantaneous Derived Earth Fault Protection (50N-n)
Default Value
Disabled
1xIn
0
A binary input.
Logic Diagram: Derived Time Delayed Earth Fault Protection
7SR45 Description of Operation
Min Max Step Change
- - -
0.2xIn 20xIn 0.1
0 s 600 s 0.01
Chapter 1 Page 19 of 34