Overview
“Underfrequency protection (SAPTUF)” function measures frequency with high accuracy, and is used for load shedding systems, remedial action schemes, gas turbine startup and so on. Separate definite time delays are provided for operate and restore.
For more detailed information on “Underfrequency protection (SAPTUF)” function, refer to ABB, Relion 670 Series manuals.
To see other supported functions, click here.
Function Identification
| Function description | IEC 61850 identification |
IEC 60617 identification |
ANSI/IEEE C37.2 device number |
| Underfrequency protection | SAPTUF | f < | 81 |
Signals & Setting Parameters
SAPTUF function block
SAPTUF Input signals
| SAPTUF Input signals | |||
| Name | Type | Default | Description |
| U3P | GROUP SIGNAL | – | Three phase group signal for voltage inputs |
| BLOCK | BOOLEAN | 0 | Block of function |
| BLKTRIP | BOOLEAN | 0 | Blocking operate output |
| BLKREST | BOOLEAN | 0 | Blocking restore output |
SAPTUF Output signals
| 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 | Blocking indication due to low amplitude | |
| FREQ | REAL | Measured frequency | |
SAPTUF Group settings (basic)
| 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 |
| IntBlockLevel | 0.0 – 100.0 | %UB | 1.0 | 50.0 | Internal blocking level in % of UBase |
| tDelay | 0.000 – 60.000 | s | 0.001 | 0.200 | Operate time delay |
| tReset | 0.000 – 60.000 | s | 0.001 | 0.000 | Time delay for reset |
| 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 value |
| TimerMode | Definite timer Volt based timer |
– | – | Definite timer | Setting for choosing timer mode |
| UNom | 50.0 – 150.0 | %UB | 1.0 | 100.0 | Nominal voltage for voltage based timer in % of UBase |
| UMin | 50.0 – 150.0 | %UB | 1.0 | 90.0 | Lower operation limit for voltage based timer in % of UBase |
| Exponent | 0.0 – 5.0 | – | 0.1 | 1.0 | For calculation of the curve form for voltage based timer |
| tMax | 0.010 – 60.000 | s | 0.001 | 1.000 | Maximum time operation limit for voltage based timer |
| tMin | 0.010 – 60.000 | s | 0.001 | 1.000 | Minimum time operation limit for voltage based timer |
SAPTUF Non group settings (basic)
| SAPTUF Non group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| GlobalBaseSel | 1 – 12 | – | 1 | 1 | Selection of one of the Global Base Value groups |
Logics & highlights
Voltage dependent inverse time characteristics for underfrequency protection SAPTUF. The time delay to operate is plotted as a function of the measured voltage, for the Exponent = 0, 1, 2, 3, 4 respectively
Simplified logic diagram for SAPTUF
