Four Step Directional Negative Phase Sequence Overcurrent Protection Ns4Ptoc (46I2) - ABB REB670 Applications Manual

Section 7
Current protection
7.4
190
SOTF and Under Time are similar functions to achieve fast clearance at asymmetrical
closing based on requirements from different utilities.
The function is divided into two parts. The SOTF function will give operation from step
2 or 3 during a set time after change in the position of the circuit breaker. The SOTF
function has a set time delay. The Under Time function, which has 2
blocking, will give operation from step 4. The 2nd harmonic restrain will prevent
unwanted function in case of transformer inrush current. The Under Time function has a
set time delay.
Below the settings for switch on to fault logics are described.
SOTF operation mode: This parameter can be set: Disabled/SOTF/Under Time/SOTF
+Under Time.
SOTFSel: This setting will select the signal to activate SOTF function; CB position open/
CB position closed/CB close command.
tSOTF: Time delay for operation of the SOTF function. The setting range is 0.000 - 60.000
s in step of 0.001 s. The default setting is 0.100 s
StepForSOTF: If this parameter is set on the step 3 pickup signal will be used as current
set level. If set disabled step 2 pickup signal will be used as current set level.
t4U: Time interval when the SOTF function is active after breaker closing. The setting
range is 0.000 - 60.000 s in step of 0.001 s. The default setting is 1.000 s.
ActUndrTimeSel: Describes the mode to activate the sensitive undertime function. The
function can be activated by Circuit breaker position (change) or Circuit breaker
command.
tUnderTime: Time delay for operation of the sensitive undertime function. The setting
range is 0.000 - 60.000 s in step of 0.001 s. The default setting is 0.300 s
Four step directional negative phase sequence
overcurrent protection NS4PTOC (46I2)
1MRK 505 337-UUS -
nd
harmonic restrain
Application manual