ABB RED615 Technical Manual page 431

1YHT530004D05 D
615 series
Technical Manual
I A _ I B _ I C _
+ +
IB
=
3
GUID-E162EE11-DEDF-49BA-B60F-E22ECF1ACAE8 V2 EN
GUID-9D592151-7598-479B-9285-7FB7C09F0FAB V1 EN
Figure 225: Operating characteristics of the stabilized earth-fault protection
function
GUID-552423CA-6FE9-4F69-8341-FFE0FF1943D4 V1 EN
Figure 226: Setting range of the operating characteristics for the stabilized
differential current principle of the earth-fault protection function
The Operate value setting is used for defining the characteristics of the function.
The differential current value required for tripping is constant at the stabilizing
current values 0.0 < IB/In < 1.0, where In is the nominal current, and the In in this
context refers to the nominal of the phase current inputs. When the stabilizing
current is higher than 1.0, the slope of the operation characteristic (ID/IB) is
constant at 50 percent. Different operating characteristics are possible based on the
Operate value setting.
Section 4
Protection functions
(Equation 57)
425