Phase Differential Protection Of A Bus (87B) - Siemens 7UT51 Instruction Manual

7UT51 v3
2.9

Phase Differential Protection of a Bus (87B)

Settings
Operational status
Minimum differential current required for pickup (87B)
Restraint based on total current level
-
Restraint for through fault causing CT saturation
Time delay before trip
Time delay before reset
Events that can control signal contacts or trip contacts
Inherent Operating Times
-
Pickup time with single ended infeed:
≥ 1.5 times 87B pickup threshold level (approx.)
I
DIFF
≥ 5.0 times 87B pickup threshold level (approx.)
I
DIFF
Dropout (approximate)
Dropout Ratio
87B dropout ratio (dropout/pickup; approximate)
Operating Tolerances (with default settings)
Pickup characteristic
Set time delays
Effect of Environmental Influences on Times and Tolerances
Supply power voltage
Ambient temperature
System frequency
Table 2.6 Specifications for Phase Differential Protection of a Bus (87B) (details in Chapter 6)
PRIM-2330C
-
Active, inactive, or block contacts; can be temporarily changed
-
using binary signal inputs
0.30 to 2.50 times I (steps 0.01)
n
Characteristic with two sloped segments (see Figure 6.3)
Through fault current restraint minimum 5.00 to 15.00 times I
(step 0.01); duration of restraint 2 to 250 cycles, or ∞; relay can
detect an evolving internal fault and release this restraint.
0.00 to 60.00 s (step 0.01 s), or ∞
0.00 to 60.00 s (step 0.01 s)
Change in operational status; pickup, dropout, trip, and reset
events, start of time delay before trip; start and end of restraint.
All events are logged, as are the differential and restraint current
levels at the time of a trip.
60 Hz
25 ms
16 ms
25 ms
0.7
±5% of characteristic value (for I < 5× I
±1% of setting value or 10 ms, whichever is greater
≤ 1% if between 80% and 115% of nominal voltage
≤ 0.5% / 10 K if between 0°C and 40°C (32°F and 104°F)
≤ 1% if between 80% and 120% of nominal frequency
Description of Relay
-
50 Hz 16 2/3 Hz
25 ms 70 ms
17 ms 25 ms
30 ms 90 ms
)
n
2
n
23