Siemens SIPROTEC 7SS523 V3.2 Manual page 296

Installation and Commissioning
Transformer
polarity reversal
7.6 Final Check of the Protection
280
Repeat the last 3 steps for all configured busbars. At the end of the measurements
the differential current must be nearly zero.
Read out the differential and stabilizing currents of module ZPS-BSZ1 with DIGSI
Plant Visualization or the measured value window with DIGSI. The differential cur-
rent must be nearly zero and the stabilizing current must be the sum of all currents.
If the plant conditions allow it, make a busbar coupling via the bus coupler bay.
Then check the polarity of the transformers in the bus coupler bay again.
The polarity of a feeder's transformer can be reversed for test purposes via a configu-
ration in DIGSI. The corresponding operating address "4601 CT-POLARITY" can be
reached via the arrow keys in the test settings or simply by pressing the F4 function
key. Entering the password F3F1F3F1F3F1 is required for this function.
After its confirmation, the three phase currents and the earth current are transmitted
to the central unit with inverted signs. The annunciations "TF RevPol $00" (FNo.
176.1195/CU) for the corresponding bay unit and the group annunciation "TF Rev-
Pol M" (FNo. 10451/CU) are reported as ON in the central unit and in the bay unit.
In the bay unit, "Fail MV.Offs." (FNo. 7652/BU) is reported as ON.
The inversion of the currents is done until the process is undone again. Then, the an-
nunciations "TF RevPol $00" (FNo. 176.1195/CU) and the group annunciation
"TF RevPol $00" in the central unit and the annunciations "Fail MV.Offs" (FNo.
7652/BU), "CT inversion" (FNo. 7656/BU) and "BB TRIP block" (FNo.
7657/BU) in the bay unit are reported as OFF.
The transformer polarity reversal is reset when the bay unit is restarted.
To finally check the protection, carry out the following steps:
In case the parameters had been changed during the testing check their settings
again. The green LED (RUN) at the central unit must shine green. The red "Error"
LED must not be lit.
The TRIP commands must be switched conductive. If there is a switch available
with test and operation position, switch it to the position "operation".
7SS52 V4 Manual
C53000-G1176-C182-1