7SG11 Argus Technical Reference
©2013 Siemens Protection Devices Limited
P20007 Page 30 of 71
2.4
Sensitive Earth-fault and Restricted Earth-fault
This element can be used for either sensitive earth-fault or high-impedance restricted earth-fault protection
schemes. The two applications are not possible simultaneously – the user must select which is required. The
restricted earth-fault scheme is described in section 2.4.1 below.
The element includes a software filter for rejection of second, third and higher harmonics of the power system
frequency. The instantaneous element, set using
Protection:
SEF/REF Current Setting
, provides a starter output. Two
sequential DTL follower timers (
Protection:
SEF/REF 1st Time Delay
and
Protection:
SEF/REF 2nd Time Delay
) plus an
additional timer (
Protection:
SEF/REF Lowset Delay
) are provided; all use the same
Protection:
SEF/REF Current Setting
. The
delayed reset function (section 2.3.3) is applied on each of the two DTL timers.
Each of the three timing elements has an output, mapped by a setting. Each timing element can be inhibited from
a status input, mapped by a setting, see Figure 2.4-1.
In multi-pole directional Argus models the SEF element is non-directional. In single-pole directional SEF models
the directional control setting applies to all the SEF Protection elements.
Figure 2.4-1
Functional Diagram – Sensitive Earth-fault/Restricted Earth-fault Elements
Table 2-13
Sensitive Earth-fault / Restricted Earth-fault Settings
Sub-menu:
Protection
Setting name
Range (
bold
= default)
Units Notes
Gn SEF Dir Control
OFF
, FWD, REV, TRI
Argus 2 Single-pole dir’n. SEF
only.
Gn SEF/REF Current Setting
0.005, 0.010…
0.050
…0.960
xIn
Gn SEF/REF 1st Time Delay
0.00, 0.01…
5.00
…20.00, 20.5
…100, 101 … 300 s
sec
Gn SEF/REF 2nd Time Delay
OFF, 0.00, 0.01…
5.00
…20.00,
20.5 …100, 101 … 300 s
sec
Gn SEF/REF Lowset Delay
0.00
, 0.01…20.00, 20.5 …100,
101 … 300 s
sec
see note 1 below
Sub-menu:
O/P Relay Config.
Setting name
Range (
bold
= default)
Units Notes – see note 1 below
Ise
P300008 Protection Functions / SEF/REF
SEF Lowset Inhib
SEF Lowset
SEF/REF Starter
SEF Delay 1 Inhib
SEF/REF Delay 1
SEF Delay 2 Inhib
SEF/REF Delay 2
Event
Event
Event
Event
SEF/REF starter
SEF/REF lowset trip
SEF/REF stage 1 trip
SEF/REF stage 2 trip
>
Dir'n SEF Fwd
*
In most models the SEF element is non-directional, in which case
the directional settings and control inputs can be ignored.
A single pole directional SEF model is available, for which the
diagram shows the logic for elements in the forward direction;
reverse is identical.
*
*
c
SEF Current Setting
SEF/REF Dir Control
SEF/REF Lowset Delay
SEF/REF 2nd Time Delay
SEF/REF 1st Time Delay
c
c
c