Siemens SIPROTEC 7SD610 - Restricted Earth Fault Protection

4.4 Restricted Earth Fault Protection
335
7SD610 Manual
C53000-G1176-C145-4
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 3I
0
”/3I
0
' (both currents in phase + or
counter-phase –); I
REF
> = setting; I
Trip
= tripping current
Differential current I
REF
>for I
N
= 1 A 0.05 A to 2.00 A Increment 0.01
for I
N
= 5 A 0.25 A to 10.00 A
Threshold angle ϕ
Limit
100° (fixed)
Trip Characteristic see Figure
Pickup tolerance for ϕ(3I
0
”, 3I
0
') < 90°
and address 221 I4/Iph CT = 1.000
and address 4113 SLOPE = 0.00
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. 35 ms 34 ms
at 2.5 · set value I
REF
> approx. 35 ms 34 ms
Dropout time, approx. 30 ms 30 ms
Drop-off to pickup ratio approx. 0.7
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