ABB ret650, Technical Manual

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10.1.4 Signals
Table 154: SAPTUF Input signals
Name Type Default Description
U3P GROUP
SIGNAL
- Three phase group signal for voltage inputs
BLOCK BOOLEAN 0 Block of function
Table 155: SAPTUF Output signals
Name Type Description
TRIP BOOLEAN General trip signal
START BOOLEAN General start signal
RESTORE BOOLEAN Restore signal for load restoring purposes
BLKDMAGN BOOLEAN Measurement blocked due to low voltage
amplitude
10.1.5 Settings
Table 156: SAPTUF Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On
- - Off Operation Off / On
StartFrequency 35.00 - 75.00 Hz 0.01 48.80 Frequency set value
tDelay 0.000 - 60.000 s 0.001 0.200 Operate time delay
tRestore 0.000 - 60.000 s 0.001 0.000 Restore time delay
RestoreFreq 45.00 - 65.00 Hz 0.01 49.90 Restore frequency if frequency is above
frequency value
10.1.6 Monitored data
Table 157: SAPTUF Monitored data
Name Type Values (Range) Unit Description
FREQ REAL - Hz Measured frequency
10.1.7 Operation principle
The underfrequency protection (SAPTUF) function is used to detect low power
system frequency. If the frequency remains below the set value for a time period
greater than the set time delay the TRIP signal is issued. To avoid an unwanted trip due
to uncertain frequency measurement at low voltage magnitude, a voltage controlled
blocking of the function is available from the preprocessing function, that is, if the
Section 10
1MRK 504 135-UEN A
Frequency protection
232
Technical manual