ABB RELION REX640 Technical Manual page 690

Protection functions
the same for all the phases. When the differential current exceeds the operating
value determined by the operating characteristic, the differential function awakes. If
the differential current stays above the operating value continuously for a suitable
period, which is 1.1 times the fundamental cycle, the OPR_LS output is activated.
The OPERATE output is always activated when the OPR_LS output is activated .
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.
Low operate value
Figure 392: Operation characteristic for biased operation of TR2PTDF
The
according to the operation characteristic:
Low operate value = Id1
Slope section 2 and Slope section 3 are determined correspondingly:
Slope section
690
I [%Ir]
d
300
200
100
I
d1
Section 1
End section 1
Low operate value of the biased stage of the differential function is determined
I
d
2
2 100 %
= ⋅
I
b 2
I
b2
100 200
Section 2
End section 2
I
b3
I
d3
I
d2
300 400
Section 3
Technical Manual
1MRS759142 F
500 I [%Ir]
b
(Equation 163)
REX640