2.4 Differential overcurrent
protection ΔI> (87)
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Figure 2.4-3 Block diagram of the differential overcurrent stage I>.
The stage I> can be configured to operate as shown in Figure
2.4-4. This dual slope characteristic allows more differential
current at higher currents before tripping.
Figure 2.4-4 Example of differential overcurrent characteristics.
The stage also includes second harmonics blocking. The second
harmonic is calculated from winding currents. Harmonic ratio
is:
100 x I
f2_Winding
/ I
f1_Winding
[%].
Fast differential overcurrent stage I>> does not include slope
characteristics and second harmonics blocking.
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