Instantaneous Sensitive Earth Fault Protection (50Sef); Figure 1-34 Logic Diagram: Sef Directional Element (67Sef); Figure 1-35 Logic Diagram: 7Sr11 Sef Instantaneous Element - Siemens 7SR11 Manual

Figure 1-34 Logic Diagram: SEF Directional Element (67SEF)

3.4.2

Instantaneous Sensitive Earth Fault Protection (50SEF)

Two sensitive earth fault elements are provided in the 7SR11 relay and four elements are provided in the 7SR12
relay.
50SEF-1, 50SEF-2, (50SEF-3 & 50SEF-4– 7SR12)
Each instantaneous element has independent settings for pick-up current 50SEF-n Setting and a follower time
delay 50SEF-n Delay. The instantaneous elements have transient free operation.
Where directional elements are present the direction of operation can be set using 50SEF-n Dir. Control setting.
Directional logic is provided independently for each 50SEF-n element e.g. giving the option of using two elements
set to forward and two to reverse.
Operation of the instantaneous earth fault elements can be inhibited from:
Inhibit 50SEF-n
79 SEF Inst Trips: 50SEF-n
50SEF-n VTSAction: Inhibit
Directional elements will not operate unless the zero sequence voltage (V
Voltage setting i.e. the residual voltage is greater than 3 times this setting and the phase is in the
Forward/Reverse operating range. If 67SEF Wattmetric is set to Enabled, the calculated residual real power
must be above the 67SEF Wattmetric Power setting for any SEF element operation. The residual power P
equal to the wattmetric component of 3V

Figure 1-35 Logic Diagram: 7SR11 SEF Instantaneous Element

©2012 Siemens Protection Devices Limited
A binary or virtual input.
When 'delayed' trips only are allowed in the auto-reclose sequence
(79 SEF Prot'n Trip n = Delayed).
Operation of the VT Supervision function (7SR1205 & 7SR1206).
I and therefore the wattmetric component of 9V
0 SEF
7SR11 & 7SR12 Description Of Operation
) is above the 67SEF Minimum
0
I
0 0
Chapter 1 Page 38 of 76
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