Time Delayed Overcurrent Protection (51); Figure 3-2 Logic Diagram: Time Delayed Overcurrent Element - Siemens 7SR45 Argus User Manual

3.2

Time Delayed Overcurrent Protection (51)

One time delayed overcurrent element is provided in the 7SR45 Argus Relay.
51-1
51-n Setting sets the pick-up current level.
A total of 7 shaped characteristics are provided from IEC and ANSI standards. An inverse definite minimum time
(IDMT) characteristic is selected using 51-n Char. A time multiplier is applied to the characteristic curves using
the 51-n Time Mult setting. Alternatively, a Definite Time Lag (DTL) can be chosen using 51-n Char. When
Definite Time Lag (DTL) is selected the time multiplier is not applied and the 51-n Delay (DTL) setting is used
instead.
The 51-n Reset setting can apply a definite time delayed reset or when the operation is configured as an IEC or
ANSI and 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 51-n MinOperate setting.
A fixed additional operate time can be added to the characteristic using 51-n Follower setting.
Operation of the time delayed overcurrent elements can be inhibited by assigning binary inputs.
Inhibit 51-n
Gn 51-n Element
Enabled
Disabled
Inhibit 51-n
Gn 50/51
Measurement
IL1
IL2
IL3
Figure 3-2
©2018 Siemens Protection Devices Limited
A binary input.
Gn 51-n Setting
Gn 51-n Char
&
Gn 51-n Time Mult
Gn 51-n Delay (DTL)
Gn 51-n MinOperate
Gn 51-n Follower
Gn 51-n Reset
c
c
c
c
Logic Diagram: Time Delayed Overcurrent Element
Chapter 1 - 7SR45 Description of Operation
Pickup
≥1
trip
Pickup
trip
Pickup
≥1
trip
Chapter 1 Page 25 of 48
General Pickup
51-n