Seg MRM3, Руководство пользователя

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TB MRM3 07.01 E 29
6.4 Primary Test
As a rule, tests with currents at the CT primary side (real
test) can be performed in the same way as tests with
secondary currents. It is recommended to carry out pri-
mary tests only as an exception and only if it is abso-
lutely necessary (for very essential protective facilities)
because in some cases the costs involved and the strain
on the system can be rather high. Many functions of the
MRM3
can be checked during normal operation of the
system due to the efficient fault and measuring value in-
dications. So it is possible, for example, to compare the
currents shown on the display with the values shown on
the ammeters in the switchboard.
6.5 Maintenance
Normally the relays are checked at regular maintenance
intervals at site. From user to user these intervals may
vary because among other things they depend on the
type of relay, the kind of application, significance of the
object to be protected, previous experience of the user
etc.
For electro-mechanical or static relays normally an an-
nual check is required. For the
MRM3 the maintenance
intervals can be much longer because:
•
the
MRM3
relays are provided with wide-ranging self-
test functions and consequently relay faults are de-
tected and indicated. It is, of course, imperative that
the internal self-supervision relay is connected to a
central display board.
•
The combined measuring functions of the
MRM3
make monitoring during operation possible.
• The trip test function (TRIP-Test) allows testing of the
output relays.
Therefore a maintenance interval of two years is suffi-
cient. When servicing all relay functions incl. setting val-
ues, trip characteristics and tripping times ought to be
thoroughly checked.