Areva MiCOM P341, Operation Manual

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P341/EN O/B11 Operation Guide
CHAPTER 4 Problem Analysis
Page 8/8 MiCOM P341
Test Check Action
3 Verify by examination of the fault
record, or by using the test port
whether the protection element is
operating correctly.
If the protection element does not
operate, verify whether the test is
being correctly applied.
If the protection element does
operate then it will be necessary to
check the programmable logic to
ensure that the mapping of the
protection element to the contacts is
correct.
4 Using the Commissioning/Test
mode function apply a test pattern
to the relevant relay output contacts
and verify whether they operate
(note the correct external
connection diagram should be
consulted). A continuity tester can
be used at the rear of the relay for
this purpose.
If the output relay does operate
then the problem must be in the
external wiring to the relay. If the
output relay does not operate this
could indicate a failure of the
output relay contacts (note that the
self tests verify that the relay coil is
being energised). Ensure that the
closed resistance is not too high for
the continuity tester to detect.
Table 5: Failure of output contacts
7.2 Failure of opto-isolated inputs
The opto-isolated inputs are mapped onto the relay internal signals using the
programmable scheme logic. If an input does not appear to be recognised by the
relay scheme logic the Commission Tests/Opto Status menu option can be used to
verify whether the problem is in the opto-isolated input itself or the mapping of its
signal to the scheme logic functions. If the opto-isolated input does appear to be
read correctly then it will be necessary to examine its mapping within the
programmable logic.
If the opto-isolated input state is not being correctly read by the relay the applied
signal should be tested. Verify the connections to the opto-isolated input using the
correct wiring diagram. Next, using a voltmeter verify that >30V dc is present on the
terminals of the opto-islated input in the energised state. If the signal is being
correctly applied to the relay then the failure may be on the input card itself.
Depending on which opto-isolated input has failed this may require replacement of
either the complete analogue input module (the board within this module cannot be
individually replaced without re-calibration of the relay) or a separate opto board.
7.3 Incorrect analogue signals
If it is suspected that the analogue quantities being measured by the relay are not
correct then the measurement function of the relay can be used to verify the nature of
the problem. The measured values displayed by the relay should be compared with
the actual magnitudes at the relay terminals. Verify that the correct terminals are
being used (in particular the dual rated CT inputs) and that the CT and VT ratios set
on the relay are correct.