4.3 Restricted earth fault protection
441
7UT613/63x Manual
C53000-G1176-C160-2
4.3 Restricted earth fault protection
Setting Ranges
Operating Time
Frequency Influence
Figure 4-6 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
>/I
NObj
0.05 to 2.00 Steps 0.01
Limit angle Ï•
REF
110° (fixed)
Trip characteristic see Figure 4-6
Pickup tolerance
(with preset characteristic parameters and one
3-phase measuring location)
5% at I <5 · I
N
Time delay T
REF
0.00 s to 60.00 s
or ∞ (no trip)
Steps 0.01 s
Time tolerance 1 % of set value or 10 ms
The set times are pure delay times
Pickup time at frequency 50 Hz 60 Hz 16.7 Hz
at 1.5 · set value I
REF
> approx.
high-speed relays 35 ms 30 ms 110 ms
high-speed relays 30 ms 25 ms 105 ms
at 2.5 · set value I
REF
> approx.
high-speed relays 33 ms 29 ms 87 ms
high-speed relays 28 ms 24 ms 82 ms
Dropout time, approx. 26 ms 23 ms 51 ms
Dropout ratio approx. 0.7
Frequency influence within the frequency tagging range
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