Earth-Fault Overcurrent Protection; Sensitive/Restricted Earth-Fault Protection; Directional Characteristics - Siemens 7SG11 Manual

Figure 1.5-3 and Figure 1.5-4 show the instantaneous highset and lowset outputs. These instantaneous operate
times i.e.delay setting td = 0.005 apply to non-directional characteristics. Where directional control is applied then
the directional element operate time (section 1.4.4) should be added to give total maximum operating time.
1.4.2

Earth-fault Overcurrent Protection

A main characteristic (IDMTL, DTL) and 3 DTL characteristics (Lowset, Highset 1 and Highset 2) are provided.
1.4.2.1 Time Delayed Characteristic
Specification as for phase-fault overcurrent (section 1.4.1.1).
1.4.2.2 Lowset, Highset 1, Highset 2
Specification as for phase-fault overcurrent (section 1.4.1.2).
1.4.3

Sensitive/Restricted Earth-fault Protection

A single element with three timing characteristics (lowset, DTL1 and DTL2) is provided.
Operate Level
Attribute
Is Current setting
I Operate level
op
Reset level
Repeatability
Variation
Note. SEF relays are required to suppress 2
minimum setting as shown in Figure 1.5-5.
Operate Time
Attribute
t ,
lowset
t , Delay setting (lowset, DTL1, DTL2)
DTL1
t
DTL2
Operating time
Repeatability
Overshoot time
Disengaging time
Variation
Figure 1.5-6 shows the sensitive earth fault starter output. This instantaneous operate time applies to non-
directional characteristics. Where directional control is applied then the directional element operate time
(section1.4.4) should be added to give total maximum operating time.
1.4.4

Directional Characteristics

Applies to Argus 2 and Argus 6 relays only.
Directional characteristics can be applied to phase-fault overcurrent elements, earth-fault overcurrent elements
and single-pole sensitive earth-fault models.
Two types of directional element exist, referred to below as type I and type II. On a particular model the type of
element in the relay can be identified from the range of the angle setting as listed below: -
©2013 Siemens Protection Devices Limited
Value
0.005, 0.010...0.960 xIn
100 % Is,
95 % I
1 %
-10 °C to +55 °C 5 %
47 Hz to 52 Hz
5 %
57 Hz to 62 Hz
nd rd
, 3
Value
0.00, 0.01...20.00, 20.5 ...100, 101 ... 300 s
lowset
t
lowset
DTL1 t
DTL1
DTL2 t
DTL1
1 % or
< 40 ms
< 42 ms
47 Hz to 52 Hz
5%
57 Hz to 62 Hz
7SG11 Argus Technical Reference
5% or 1 % In
5% or 1 % In
op,
and higher harmonics and have a frequency response at
, 1% or 10 ms
, 1% or 10 ms
+ t , 1% or 10 ms
DTL2
10 ms
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