1 2 3 4 A - SIPROTEC

Functions
2.4 Time Overcurrent Protection for Phase and Residual Currents
2.4.2.1 Setting Notes
General
164
Note
The first overcurrent protection for phase currents is described in the setting instructions. The parameter
addresses and message numbers of the second and third overcurrent protection are described at the end of
the setting instructions under „Additional Overcurrent Protection Functions for Phase Currents“.
During configuration of the functional scope (section 2.1.3) the characteristic type is determined under address
120 DMT/IDMT Phase. Only the settings for the selected characteristic can be performed here. The definite
time stages I>> and I> are available in all cases.
If a second or third phase overcurrent protection is used, this must be configured accordingly in address 130
DMT/IDMT Phase2 and 132 DMT/IDMT Phase3.
Each protection function must be assigned to a side of the main protected object or another 3-phase current
measuring location. This can be carried out separately for each protection function (section 2.1.4 under margin
heading „Additional Three-phase Protection Functions“). Consider also the assignment of the measured
current inputs of the device against the measuring locations (current transformer sets) of the power plant
(section 2.1.4 under margin heading „Assignment of 3-phase Measuring Locations“).
Note
If the time overcurrent protection is assigned to a side of the main protected object, the current values are set
referred to the rated current of that side II/I NS. In other cases, current values are set in amps.
At address 2001 PHASE O/C, phase overcurrent protection may be switched to ON or OFF. The option Block
relay allows to operate the protection but the trip output relay is blocked.
Address 2008 MANUAL CLOSE determines which phase current stage is to be activated instantaneously with
a detected manual close. Settings I>> instant. and I> instant. can be set independently from the selected
type characteristics;Ip instant. is only available if one of the inverse time stages is configured. This
setting can only be made with DIGSI under Additional Settings.
If time overcurrent protection is applied on the feeding side of a transformer, select the higher stage
I>>, which does not pick up by the inrush current or set the manual close feature to Inactive.
In address 2002 InRushRest. Ph inrush restraint (restraint with 2nd harmonic) is enabled or disabled for all
phase current stages of time overcurrent protection (except stage I>>). Set ON if one time overcurrent protection
stage is to operate at the supply side of a transformer. Otherwise, retain setting OFF. If you intend to set a
very small pickup value for any reason, consider that the inrush restraint function cannot operate below 10 %
nominal current (lower limit of harmonic filtering).
SIPROTEC, 7UT6x, Manual
C53000-G1176-C230-2, Release date 06.2012