Line Application Example - ABB Relion 670 Series Applications Manual

Section 7
Current protection
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
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
7.4.3.6

Line application example

The Four step residual overcurrent protection EF4PTOC (51N/67N) can be used in different ways.
Below is described one application possibility to be used in meshed and effectively grounded
systems.
The protection measures the residual current out on the protected line. The protection function
has a directional function where the polarizing voltage (zero-sequence voltage) is the polarizing
quantity.
The polarizing voltage and current can be internally generated when a three-phase set of voltage
transformers and current transformers are used.
144
nd
harmonic restrain blocking, will give operation
1MRK 511 358-UUS A
M15282-184 v7
Application manual