ABB RELION REX640 - Page 726

low stage is blocked by the waveform blocking functionality, the BLKDWAV output is
activated according to the phase information.
When required, the operating outputs of the biased low stage can be blocked by the
external control signals BLK_OPR_LS and BLOCK.
The operation of the protection relay is affected by biasing as shown in Figure 411 .
I
b2
I
d1
I
d2
I
b3
I
d3
100
200
300
100 200 300 400 500
End section 2End section 1
Low operate value
Section 1 Section 2 Section 3
I
d
[%Ir]
I
b
[%Ir]
Figure 411: Operation characteristic for biased operation of TR3PTDF
The Low operate value setting of the biased stage of the differential function is
determined according to the operating characteristics curve:
Low operatevalue Id= 1
(Equation 170)
The Slope section 2 setting is determined correspondingly:
Slope section 2 = ⋅
Id
Ib
2
2
100 %
(Equation 171)
The second turning point End section 2 can be set in the range 100...500 %.
The slope of the operating characteristic curve of the differential function varies in
three different sections of the range.
Protection functions
1MRS759142 F
726 REX640
Technical Manual