1 2 3 4 A - SIPROTEC

SIPROTEC, 7UT6x, Manual
C53000-G1176-C230-2, Release date 06.2012
Functions
2.1 General
When using the circuit breaker failure protection (section 2.17) (address 470 BREAKER FAIL.AT) please
make sure that the assignment of this protection function corresponds to that side or measuring location whose
current actually flows through the circuit breaker to be monitored. In the example shown in Figure 2-2, the
assignment must be set in address BREAKER FAIL.AT to Side 1 if you want to monitor the circuit breaker
of the high-voltage side, since both currents flow through the breaker (via M1 and M2). If on the other hand you
want to monitor the circuit breaker of the cable feeder, you set address BREAKER FAIL.AT to Measuring
loc.5. When assigning the circuit breaker failure protection function, make sure that the breaker auxiliary
contacts or feedback information are correctly configured and assigned.
If you do not wish to assign any measuring location or side to the circuit breaker failure protection because you
want only the breaker position to be processed, set BREAKER FAIL.AT to Ext. switchg. 1. In this case,
the protection handles only the breaker position but not any current flow for its operation. This allows even to
monitor a circuit breaker the current of which is not connected to the device. But you have to ensure that the
feedback information of this breaker is correctly connected and configured.
In 7UT613/63x, you can monitor another m.c.b. using the second circuit breaker failure protection. The
considerations for the assignment in address 471 BREAKER FAIL2AT correspond to those for the first circuit
breaker failure protection.
Further 1-phase Protection Functions
The 1-phase protection functions evaluate the 1-phase measuring current of 1-phase additional measuring
input. It is irrelevant in this context whether the connect current belongs to the main protected object or not.
Only the current connected to the additional measuring input is decisive.
The device must now be informed which current is to be evaluated by the 1-phase protection functions.
Address 424 DMT/IDMT E AT assigns the time overcurrent protection for earth current (section 2.5) to a
1-phase additional measuring input. In most cases this will be the current flowing in the neutral leads of an
earthed winding, measured between the starpoint and the earth electrode. In figure 2-2 the auxiliary measuring
location X3 would be a good choice; so you set here AuxiliaryCT IX3. As this protection function is
autonomous, i.e. independent of any other protection function, any 1-phase additional measuring input can be
used. This requires, however, that it is not a high-sensitivity measuring input and, of course, that it is connected.
Please note also that the earth overcurrent protection will receive from the auxiliary measuring location
assigned here not only its measured value, but also circuit breaker information (current flow and manual-close
detection).
The second earth overcurrent protection can be assigned to another single-phase measuring location
according to the same aspects under address 438 DMT/IDMT E2 AT.
Address 427 DMT 1PHASE AT assigns the single-phase time overcurrent protection (section 2.7). This
protection function is mainly used for high-sensitivity current measurement, e.g. for tank leakage protection or
high-impedance differential protection. Therefore a high-sensitivity 1-phase additional measuring input is
particularly suited for it. In figure 2-2 this would be the auxiliary measuring location X4; so you set this address
to AuxiliaryCT IX4. However, it is also possible to assign this protection function to any other additional
measuring input used, regardless of its sensitivity.
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