Siemens SIPROTEC 4 7SD80, Manual

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Voltage and Phase Rotation Check
If the device is connected to voltage transformers, these connections are checked using primary values. For
devices without voltage transformer connection the rest of this margin heading may be omitted.
The voltage transformer connections are individually tested at either end of the object to be protected. At the
other end, the circuit breaker initially remains open.
•
Having closed the circuit breaker, none of the measurement monitoring functions in the device must
respond.
–
If there was a fault indication, however, the Event Log or spontaneous indications could be checked
to investigate the reason for it.
– At the indication of balance monitoring there might actually be asymmetries of the primary system.
If they are part of normal operation, the corresponding monitoring function is set less sensitive (see
Section
2.14.1 Measurement Supervision under margin heading “Symmetry Monitoring”).
The voltages can be read as primary and secondary values on the display at the front, or called up in the
PC via the operator or service interface, and compared with the actual measured quantities. Besides the
magnitudes of the phase-to-ground and the phase-to-phase voltages, the phase differences of the
voltages are also displayed so that the correct phase sequence and polarity of individual transformers can
also be seen.
•
The voltage magnitudes should be almost equal. All three angles φ (V
Lx
–V
Ly
) must be approximately 120°.
– If the measured quantities are not plausible, the connections must be checked and revised after
switching off the line. If the phase difference between two voltages is 60° instead of 120°, one
voltage must be polarity- reversed. The same applies if there are phase-to-phase voltages which are
almost equal to the phase-to-ground voltages instead of having a value that is √3 larger. The meas-
urements are to be repeated after correcting the connections.
– In general, the phase rotation is a clockwise phase rotation. If the system has an anti-clockwise
phase rotation, this must be identical at all ends of the protected object. The phase assignment of
the measured quantities has to be checked and, if required, corrected after the line has been
isolated. The measurement must then be repeated.
•
Open the miniature circuit breaker of the feeder voltage transformers. The measured voltages in the
operational measured values appear with a value close to zero (small measured voltages are of no conse-
quence).
–
Check in the Event Log and in the spontaneous indications that the VT mcb trip was noticed (indica-
tion
>FAIL:Feeder VT
“ON”, no. 361). It has to be assured beforehand that the position of the VT
mcb is connected to the device via a binary input.
•
Close the VT mcb again: The above indication appears in the spontaneous indications as “OFF”,
i.e.
>FAIL:Feeder VT
“OFF”.
– If one of the indications does not appear, check the connection and routing of these signals.
– If the “ON” state and the “OFF” state are swapped, the contact type (H-active or L-active) must be
checked and corrected.
•
The protected object is switched off again.
•
This check must be performed at both ends.
Current Test
The connections of the current transformers are tested with primary values. A load current of at least 5% of
the rated operational current is required. Any direction is possible.
This test cannot replace visual inspection of the correct current transformer connections. Therefore, the
inspection according to Section “Checking the System Connections” is a prerequisite.
Mounting and Commissioning
3.3 Commissioning
240 SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018