92
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
Directional earth fault protection, high-set stage, Io>>-> and instantaneous stage,
Io>>>->
Start current
Start voltage
Operate time
Operation mode
Operation criteria
Operation direction
Basic angle ϕ
b
Operation characteristic
Intermittent E/F
Measuring mode
Drop-off time of the operate time counter
1.0…200.0% of In
2.0…100.0% of Un
0.1…300.0 s
Not in use
Definite time
Instantaneous
Basic angle & Uo
Basic angle
IoSin/Cos & Uo
IoSin/Cos
Non-directional Io
Non-directional Uo
Forward
Reverse
-90°
-60°
-30°
0°
IoSin(ϕ)
IoCos(ϕ)
Not active
Active
Peak-to-peak
Fundamental frequency
0...1000 ms
Note! The values below apply when f/fn = 0.95...1.05
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
±2.5% of set value + 0.0005 x In
±2.5% of set value or + 0.01 x Un
Phase angle ±2°
Injected neutral current > 2.0 x start current
and residual voltage > 2.0 x start voltage:
internal time < 72 ms
total time < 80 ms
40...1000 ms (depends on the minimum pulse width set
for the trip output)
0.95
< 50 ms
±2% of set value or ±20 ms
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