ABB RELION 620 Series Technical Manual page 527

1MRS757644 F
620 series
Technical Manual
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Figure 264: Operating characteristics of the protection. (LS) stands for the biased
low stage and (HS) for the instantaneous high stage
The OPERATE output is activated always when the OPR_HS output activates .
The internal blocking signals of the differential function do not prevent the operate
signal of the instantaneous differential current stage. When required, the operate
outputs of the instantaneous high stage can be blocked by the BLK_OPR_HS and
BLOCK external control signals.
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Figure 265: Operation logic of instantaneous high stage
Reset of the blocking signals (de-block)
All three blocking signals, that is, waveform and second and fifth harmonic, have a
counter, which holds the blocking on for a certain time after the blocking conditions
have ceased to be fulfilled. The deblocking takes place when those counters have
elapsed. This is a normal case of deblocking.
The blocking signals can be reset immediately if a very high differential current is
measured or if the phase difference of the compared currents (the angle between the
compared currents) is close to zero after the automatic vector group matching has been
made (in a normal situation, the phase difference is 180 degrees). This does not,
Section 4
Protection functions
521