Technical Data
4.4 Restricted Earth Fault Protection
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
590
4.4
Restricted Earth Fault Protection
Setting ranges
Operating Time
Figure 4-1
Tripping characteristic of the restricted earth fault protection depending on the earth current
ratio 3
I
0
”/3
I
0
' (both currents in phase + or counter-phase –);
I
REF
> = setting;
I
REF
= tripping
current
Differential Current
I
EDS
>
for
I
N
= 1 A
0.05 A to 2.00 A
Increment 0.01 A
for
I
N
= 5 A
0.25 A to 10.00 A
Threshold angle
ϕ
EDS
100° (fixed)
Trip characteristic
see Figure below
Pick-up tolerance
for
ϕ
(3
I
0
", 3
I
0
') < 90
o
and address 221 I4/Iph CT =
and address 4113 SLOPE =
5 % plus
±
0.01 ·
I
N
Delay time T
EDS
0.00 s to 60.00 s
or
∞
(no trip)
Increments 0.01 s
Expiry tolerances
1 % of set value or 10 ms
The set times are pure delay times
Pickup time at frequency
50 Hz
60 Hz
at 1.5 · set value
I
REF
> approx.
high-speed relays
35 ms
34 ms
high-speed relays
30 ms
29 ms
at 2.5 · set value
I
REF
> approx.
high-speed relays
35 ms
34 ms
high-speed relays
30 ms
29 ms
Dropout time, approx.
30 ms
30 ms
Dropout ratio
Approx. 0.7
