ABB RELION 620 Series Technical Manual page 524

Section 4
Protection functions
518
The stage can be blocked internally by the second or fifth harmonic restraint, or by
special algorithms detecting inrush and current transformer saturation at external
faults. When the operation of the biased low stage is blocked by the second harmonic
blocking functionality, the BLKD2H output is activated.
When operation of the biased low stage is blocked by the fifth harmonic blocking
functionality, the BLKD5H output is activated. Correspondingly, when the operation
of the biased low stage is blocked by the waveform blocking functionality, the
BLKDWAV output is activated according to the phase information.
When required, the operate outputs of the biased low stage can be blocked by the
BLK_OPR_LS or BLOCK external control signals.
I [%Ir]
d
300
200
100
I
d1
Low operate value
Section 1
End section 1
GUID-EAAB6851-B6A9-4A69-B962-1725A4928D54 V3 EN
Figure 262: Operation characteristic for biased operation of TR2PTDF
The Low operate value of the biased stage of the differential function is determined
according to the operation characteristic:
Low operate value = Id1
Slope section 2 and Slope section 3 are determined correspondingly:
I
d
2
Slope section 2 100
= ⋅
I
b 2
GUID-D1C2CAED-3D58-4405-A79D-17B203A8D3A9 V4 EN
I
d 3
Slope section 3 100
= ⋅
I
b 3
GUID-72224800-6EE1-48E7-9B57-4ABE89DB350C V1 EN
I
b2
I
d2
100 200
Section 2
End section 2
%
%
1MRS757644 F
I
b3
I
d3
300 400 500
Section 3
Technical Manual
I [%Ir]
b
(Equation 74)
(Equation 75)
620 series