Functionality; Overfrequency Protection Saptof (81) - ABB REC650 ANSI Technical Manual

1MRK 511 287-UUS A
8.2
8.2.1
8.2.2
Technical manual
Function
Reset time, pickup function
Operate time delay
Restore time delay

Overfrequency protection SAPTOF (81)

Identification
Function description
Overfrequency protection

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 operate.
SAPTOF (81) is provided with an undervoltage blocking.
Range or value
At 50 Hz: 60 ms typically at f
set
+0.5 Hz
At 60 Hz: 50 ms typically at f
set
+0.5 Hz
(0.000-60.000)s
(0.000-60.000)s
IEC 61850 IEC 60617
identification identification
SAPTOF
SYMBOL-O V1 EN
Section 8
Frequency protection
Accuracy
-0.5 Hz to f -
set
-0.5 Hz to f
set
<250 ms
<150 ms
ANSI/IEEE C37.2
device number
81
f >
195