Siemens SIPROTEC 7UT613 series Manual page 414

3 Mounting and Commissioning
Allocation and Di-
rection Test
414
• Open the miniature circuit breaker of the feeder voltage transformers. The mea-
sured voltages in the operational measured values appear with a circuit close to
zero (small measured voltages are of no consequence).
– Check in the Event Log and in the spontaneous annunciations that the VT mcb
trip was noticed (annunciation ">Fail:Feeder VT ON", No 361). Beforehand it has
to be assured that the position of the VT mcb is connected to the device via a
binary input.
• Close the VT mcb again: The above indications appear under the "going" operation-
al indications, i.e. ">VT mcb OFF".
– If one of the annunciations does not appear, the connection and allocation of
these signals must be checked.
– If the "ON" and "OFF" messages are exchanged, then the breaker auxiliary
contact type (H-active or L-active) should be checked and corrected if necessary.
• Finally, the protected object or the voltage measuring location is switched off.
Voltages are also used for calculation of powers and metering of energy. Therefore, it
must be checked whether the connected voltages have correct relationship with
respect to the currents which are to be used for power calculation. When using power
protection functions (reverse power protection, forward power supervision) the correct
allocation and polarity are prerequisite for the correct function of this protective func-
tion.
Primary tests are preferred as secondary tests cannot prove the correct polarity.
A load current of at least 5 % of the rated operational current is required. Any direction
is possible but must be known.
• In a first step, check whether power measurement is carried out at the desired mea-
suring location, i.e. that the assignment of the 3-phase voltage transformer set is
made correct. The powers are always calculated from the connected voltages and
the currents of that measuring location to which the voltages are assigned. If the
voltage inputs are assigned to a side of the protected object with more than one
measuring location, the sum of the currents flowing into the protected object is de-
cisive.
Address is relevant 261 VT SET. Refer to Subsection 2.1.4 under margin heading
„Assignment of Voltage Measuring Inputs".
• With closed circuit breaker, the power values can be viewed as primary and sec-
ondary measured values in the front display panel or via the operator or service in-
terface with a personal computer.
Here, again, the „Web-monitor" is a comfortable help as the vector diagrams also
show the correlation between the currents and voltages. Cyclically and acyclically
swapped phases can easily be detected (see figure 3-41).
• With the aid of the measured power values you are able to verify that they correlate
to the load direction, reading either at the device itself or in DIGSI
P positive, if active power flows into the protected object,
P negative, if active power leaves the protected object,
Q positive, if (inductive) reactive power flows into the protected object,
Q negative, if (inductive) reactive power leaves the protected object.
7UT613/63x Manual
C53000-G1176-C160-2