Siemens SIPROTEC 4 7UT6 Series Manual page 33

Note that this is not applicable to the protected object busbar (address 105 PROT. OBJECT= 1ph Busbar
and address 105 PROT. OBJECT= 3ph Busbar).
Restricted Earth Fault Protection 2
The same is true in 7UT613/63x for the second potential restricted earth fault protection at address 114 REF
PROT. 2
Dynamic Pickup Switching for Overcurrent Protection
The dynamic parameter switching (address 117 COLDLOAD PICKUP) permits temporary switching to alterna-
tive pickup values in case of overcurrent protection function for phase currents, zero sequence currents and
earth currents. Further information is given in Section
Protection.
Overcurrent Protection for Phase Currents
To select the characteristic group according to which the phase overcurrent time protection is to operate use
address 120 DMT/IDMT Phase. This protection is not applicable for single-phase busbar protection (address
105 PROT. OBJECT= 1ph Busbar). If it is only used as definite time overcurrent protection (O/C), set
Definite Time. In addition to the definite time overcurrent protection an inverse time overcurrent protec-
tion may be configured, if required. The latter operates according to an IEC-characteristic (TOC IEC), to an
ANSI-characteristic (TOC ANSI) or to a user-defined characteristic. In the latter case, the trip time character-
istic (User Defined PU) or both the trip time characteristic and the reset time characteristic (User def.
Reset) are configured. For the characteristics refer to Technical Data.
Time overcurrent protection 2 and 3 for phase currents
With 7UT613/63x you have the option to use two further phase time overcurrent protection functions. This
enables you to implement one time overcurrent protection each on various sides of the protected object or on
various 3-phase measuring locations independent of each other. For DMT/IDMT Phase2, you may select
from the same options as for the first time overcurrent protection under address 130, the same applies under
address 132 for DMT/IDMT Phase3. The selected options may be the same or different for the three time
overcurrent protection functions.
Time overcurrent protection for zero-sequence currents
The type of characteristics used for the zero sequence (residual) overcurrent time protection can be set in
address 122 DMT/IDMT 3I0. The same options are available as for the phase overcurrent protection.
However, for zero sequence current time overcurrent protection the settings may be different to the settings
selected for phase time overcurrent protection. This protection function always acquires the residual current
3Ι0 of the supervised side. This current is calculated from the sum of the corresponding phase currents. This
measuring location may be different from that of the phase overcurrent protection. Note that the zero
sequence overcurrent protection is not possible on single-phase protected objects (address 105 PROT.
OBJECT = 1 phase transf. or 1ph Busbar).
Time overcurrent protection 2 and 3 for zero sequence currents
With 7UT613/63x you have the option to use two further zero-sequence current time overcurrent protection
functions. This enables you to detect the zero sequence current at various 3-phase measuring locations inde-
pendent of each other. For DMT/IDMT 3I0 2, you may again select from the same options under address
134. Similar considerations apply, under address 136, for DMT/IDMT 3I0 3. The selected options may be the
same or different for the three time overcurrent protection functions.
Time Overcurrent Protection for Earth Current
There is another earth current time overcurrent protection which is independent from the before-described
zero sequence time overcurrent protection. This protection, to be configured in address 124 DMT/IDMT
Earth, acquires the current connected to a single-phase current measuring input. In most cases, it is the star-
point current of an earthed starpoint (for transformers, generators, motors or shunt reactors). For this protec-
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
2.6 Dynamic Cold Load Pickup for Time Overcurrent
Functions
2.1 General
33