ABB Relion 670 Series RES670, Technical Manual

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10.2.2 Functionality
Overfrequency protection function SAPTOF (81) is applicable in all situations, where
reliable detection of high fundamental power system frequency is needed.
Overfrequency occurs because of sudden load drops or shunt faults in the power network.
Close to the generating plant, generator governor problems can also cause over frequency.
SAPTOF (81) measures frequency with high accuracy, and is used mainly for generation
shedding and remedial action schemes. It is also used as a frequency stage initiating load
restoring. A definite time delay is provided for trip.
SAPTOF (81) is provided with an undervoltage blocking.
The operation is based on positive sequence voltage measurement and requires two phase-
phase or three phase-neutral voltages to be connected. For information about how to
connect analog inputs, refer to
Application manual/IED application/Analog inputs/
Setting guidelines
10.2.3 Function block
ANSI06000280-2-en.vsd
SAPTOF (81)
V3P*
BLOCK
BLKTRIP TRIP
PICKUP
BLKDMAGN
FREQ
ANSI06000280 V2 EN
Figure 104: SAPTOF (81) function block
10.2.4 Signals
Table 168: SAPTOF (81H) Input signals
Name Type Default Description
V3P GROUP
SIGNAL
- Three phase group signal for voltage inputs
BLOCK BOOLEAN 0 Block of function
BLKTRIP BOOLEAN 0 Blocking operate output
Section 10
1MRK 511 365-UUS A
Frequency protection
304 Phasor measurement unit RES670 2.1 ANSI
Technical manual