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Mounting And Commissioning
3.2 Checking Connection
Visual Check
Check the cubicle and the devices for damage, condition of the connections etc., and device earthing.
Secondary Check
This test does not undertake to check the individual protection functions for the accuracy of their pick-up values
and characteristic curves. Unlike analog electronic or electromechanical protective devices, no protection func-
tion test is required within the framework of the device test, since this is ensured by the factory tests. Protection
functions are only used to check the device connections.
A plausibility check of the analog-digital converter with the operational measured values is sufficient since the
subsequent processing of the measured values is numerical and thus internal failures of protection functions
can be ruled out.
Where secondary tests are to be performed, a three-phase test equipment providing test currents and voltages
is recommended (e.g. Omicron CMC 56 for manual and automatic testing). The phase angle between currents
and voltages should be continuously controllable.
The accuracy which can be achieved during testing depends on the accuracy of the testing equipment. The
accuracy values specified in the Technical data can only be reproduced under the reference conditions set
down in IEC 60 255 resp. VDE 0435/part 303 and with the use of precision measuring instruments.
Tests can be performed using the currently set values or the default values.
If unsymmetrical currents and voltages occur during the tests it is likely that the asymmetry monitoring will fre-
quently pickup. This is of no concern because the condition of steady-state measured values is monitored
which, under normal operating conditions, are symmetrical; under short circuit conditions these monitorings are
not effective.
Note
If during dynamic testing, measured values are connected from or reduced to zero, a sufficiently high value
should be present at least one other measuring circuit (in general a voltage), to permit frequency adaptation.
Measured values in earth paths of voltage or current (IEE, UE) can not adapt the scanning frequency. To check
them a sufficiently high value measured value should be present in one of the phases.
Wiring
It is particularly important to check the correct wiring and allocation of all device interfaces. The margin heading
titled"Test function for checking the binary inputs and outputs" provides additional information to this end.
For analog inputs a plausibility check can be controlled as described above under the margin title "Secondary
Testing".
Function Check
The only functional test required for protective relays is a plausibility check of the operational measured values
by means of some secondary test equipment; this is to ensure that no damage has occurred during transit (see
also side title "Secondary Testing").
LEDs
After tests where the displays appear on the LEDs, these should be reset in order that they present information
only on the currently executed test. This should be done at least once each using the reset button on the front
panel and via the binary input for remote reset (if allocated). Observe that an independent reset occurs also on
the arrival of a new fault and that setting of new indications can be optionally made dependent on the pickup
or a trip command (parameter 201 FltDisp.LED/LCD).
80
SIPROTEC, 7VU681, User Manual
C53000-G1176-C368-1, Release Date 07.2012
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