Seg MRM3, Руководство пользователя

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28 TB MRM3 07.01 E
6.3.2 Testing the START-STOP-RUNNING
Recognition
In a secondary test this elementary function can only be
reliably tested if the test source can generate the exact
chronological course of a starting current. If ever possi-
ble this should be carried out as primary test. Under all
normal start conditions, the status indications should be
signalled correctly. Please bear in mind: the STOP con-
dition is only signalled after the STOP time has elapsed
and RUNNING is only indicated after elapse of the
start recognition time the earliest. Dependent on the ac-
tual kind of start or on the spectrum of possible varying
starting conditions, modification of both parameters
might be necessary.
6.3.3 Testing the Pick-Up and Disengaging
Values
For optimal protection many functions in this motor pro-
tection relay are interlinked and hence it is not possible
to have all protective elements tested independently from
each other.
For all functions linked with the
START/STOP/RUNNING recognition, a start simulation
has to be performed so that the function can be tested
under real conditions. Some of the tests could be simpli-
fied if special parameters would be set, but in most of
the cases this is not wanted.
Hence for testing the short-circuit element I>>
RUNNING
, for
instance, the MRM3 has to recognise the simulated run-
ning condition firstly. The test source must be able to
copy the course of the motor current exactly as it is in
reality. The required test short-circuit current can only be
injected after the
MRM3 has recognised the running
condition. The test conditions of the other elements, i.e.:
I>
I<
I>> Start
I>> RUNNING
have to be adjusted according to the application of the
selected parameters.
6.3.4 Testing the thermal image
For the thermal image there is no start simulation re-
quired. But for true propositions it is important that each
start proceeds from distinct start conditions. The thermal
behaviour of the motor is taken into account in the ther-
mal image. This means that the time for simulated cool-
ing down and for the store to be back to zero after a
test can be accordingly. (The store can also be reset
manually). As general rule applies that at constant cur-
rent 99 % of the thermal processes have reached their
final value after 5 times the time constant (warming up
or cooling down).
6.3.5 Testing the Control Inputs
Prior to the test it should be ensured that the voltage
ranges of the inputs (jumper) are correctly adjusted (see
chapter 3.1.4).
6.3.6 Testing the CB Failure Protection
For this test the test source must be able to simulate a
circuit breaker and switch-off the current after a select-
able time when the
MRM3 was triggered (see chapter
5.4.15). To meet these requirements, the test source
must have a respective signal input and a timer for
switching-off the current.