ABB Relion 650 Series Technical Manual page 267

1MRK 506 326-UUS B
8.2.7.3 Blocking
It is possible to block Over frequency protection (SAPTOF, 81) completely, by binary input signals
or by parameter settings, where:
BLOCK:
If the measured voltage level decreases below the setting of
function Signal Matrix for analog inputs (SMAI), both the PICKUP and the TRIP outputs, are
blocked.
8.2.7.4 Design
The frequency measuring element continuously measures the frequency of the positive sequence
voltage and compares it to the setting PUFrequency. The frequency signal is filtered to avoid
transients due to switchings and faults in the power system. The design of Over frequency
protection (SAPTOF, 81) is schematically described in figure 133.
ANSI09000033 V1 EN-US
Figure 133: Schematic design of overfrequency protection SAPTOF (81)
Line distance protection REL650
Technical manual
blocks all outputs
BLOCK
freqNotValid
Frequency Comparator
f > PUFrequency
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MinValFreqMeas in the preprocessing
BLOCK
OR
PICKUP
Definite Time Delay
TimeDlyOperate
TRIP
Section 8
Frequency protection
M14958-13 v4
M14958-24 v5
BLKDMAGN
Pickup
&
Trip
Output
Logic
PICKUP
TRIP
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