Siemens 7UT51

2
Description of Relay
7UT51 v3
24 PRIM-2330C
2.10 Ground Differential Protection (87N) (Optional with
7UT513)
Table 2.7
Specifications for Ground Differential Protection (87N) (details in Chapter 7)
Settings
Operational status Active, inactive, or block
-
contacts; choice can be temporarily
changed using binary
-
signal inputs
Minimum differential current required for pickup (87N) 0.05 to 2.00 times
I
n
(step 0.01)
The critical limit angle that determines the restraint of the
protection (corresponding value of k)
130° (
k
≈1), 120° (
k
≈1.4), 110° (
k
≈2), 100° (
k
≈4), 90° (
k
→∞),
Inrush restraint based on 2nd harmonic current 10% to 80% of fundamental current (step 1%); restraint is
released when the differential current exceeds a set value
(1.0 to 20.0 times
I
n
, step 0.1).
Time delay before trip 0.00 to 60.00 s (step 0.01 s), or ∞
Time delay before reset 0.00 to 60.00 s (step 0.01 s)
Events that can control signal contacts, trip contacts, or
LEDs
Change in operational status; pickup, dropout, trip, and reset
events, start of time delay before trip. All events are logged, as
are the amplitude of the ground current and the phase
-
angle
difference at the time of a trip.
Inherent Operating Times
Pickup time with single
-
ended infeed: 60 Hz 50 Hz 16
-
2/3 Hz
I
DIFF
≥ 1.5 times 87N pickup threshold level (approx.) 25 ms 25 ms 75 ms
I
DIFF
≥ 5.0 times 87N pickup threshold level (approx.) 17 ms 17 ms 25 ms
Dropout (approximate) 25 ms 30 ms 90 ms
Dropout Ratio
87N dropout ratio (dropout/pickup; approximate) 0.7
Operating Tolerances (with default settings)
Pickup characteristic ±5% of characteristic value (for
I < 5× I
n
)
Set time delays ±1% of setting value or 10 ms, whichever is greater
Effect of Environmental Influences on Times and Tolerances
Supply power voltage ≤ 1% if between 80% and 115% of nominal voltage
Ambient temperature ≤ 0.5% / 10 K if between 0°C and 40°C (32°F and 104°F)
System frequency ≤ 1% if between 80% and 120% of nominal frequency