Siemens siprotec 7SD5 User Manual

3.3 Commissioning
493
7SD5 Manual
C53000-G1176-C169-1
• Having closed the local circuit breaker, none of the measurement monitoring func-
tions in the device may respond.
– If there was a fault annunciation, however, the Event Log or spontaneous annun-
ciations 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 mon-
itoring function is set less sensitive (see Section 2.22.1 under margin heading
„Symmetry Monitoring“).
The voltages can be read 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 as
primary or secondary values. Besides the magnitudes of the phase-to-phase and
the phase-to-earth voltages, the phase angles can be read out, thus enabling to
verify the correct phase sequence and polarity of individual voltage transformers.
The voltages can also be read with the „WEB-Monitor“ (see below, „Current Test“).
• The voltages should be almost equal. All three angles ϕ (U
Lx
–U
Ly
) must be approx-
imately 120°.
– If the measured quantities are not plausible, the connections must be checked
and revised after switching off the line. If the phase difference angle 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 almost equal the phase-to-
earth voltages instead of having a value that is √3 greater. The measurements
are to be repeated after setting the connections right.
– In general, the phase rotation is a clockwise phase rotation. If the system has a
counter-clockwise phase rotation, this must go for all ends of the protected
object. The measured value allocation must be checked and corrected, if re-
quired, after the line has been isolated. The phase rotation check must then be
repeated.
• Open the miniature circuit breaker of the feeder voltage transformers. The mea-
sured voltages in the operational measured values appear with a value 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 (indication „>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 annun-
ciations as „OFF“, i.e. „>FAIL:Feeder VT“ „OFF“.
– If one of the indications does not appear, the connection and allocation of these
signals must be checked.
– If the „ON“ state and the „OFF“ state are swapped, the contact type (H–active or
L–active) must be checked and remedied.
• The protected object is switched off.
• The check must be carried out for all ends.
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English