3 Mounting and Commissioning
308
7SD610 Manual
C53000-G1176-C145-4
• 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 symmetry 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 2.15.1 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-earth and
the phase-to-phase voltages, the phase differences of the voltages are also dis-
played so that the correct phase sequence and polarity of individual transformers
can also be seen. The voltages can also be read with the „WEB-Monitor“ (see
below, „Current test“).
• The voltages have to 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 corrected 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-earth voltages instead of having a value that is √3 larger. The measure-
ments 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. Subsequently the mea-
surement has to be repeated.
• Open the circuit breaker for voltage transformers of the feeder. The measured volt-
ages in the operational measured values appear with a value close to zero (small
measured voltages are of no consequence).
– Check the Event Log and the spontaneous indications to make sure that the VT
mcb trip was noticed (indication „>FAIL:Feeder VT“ „ON“, No. 361). This re-
quires that the position of the circuit breaker for voltage transformers is connect-
ed to the device via a binary input.
• Close the circuit breaker for voltage transformers: The above indication is displayed
in the spontaneous indications 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 „ON“ state and „OFF“ state are swapped, the contact type
(H–active or L–active) must be checked and corrected.
• The protected object is switched off.
• This check must be performed at both ends.
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