Siemens SIRIUS 3UG4 Equipment Manual page 285

Hysteresis
Hysteresis is the continuation of an effect within the hysteresis range after its cause has been
removed; its purpose is to prevent repeated response in the threshold value range.
Figure B-1 Explanation of hysteresis
If, after the upper threshold value has been overshot to such an extent that switching was
necessary, the measured value returns to the normal range, and switching over to the correct
range will not take place until a measured value which undershoots the hysteresis threshold has
been reached. The same applies if the lower threshold value is undershot.
The hysteresis is only active if the "Reset response" parameter is set to autoreset.
Possible indications on the display: Hyst
Initialization
When the monitoring relay is connected to the supply voltage, the initialization phase starts and
internal functional tests are performed. During the initialization phase that lasts approximately
1.6 s, the connection to the 3UL23 residual-current transformer is one of the things that is
checked. During this time, no measurement or monitoring of the fault current takes place. - - A
is shown on the display. The relay switching behavior during the initialization phase can be
determined with the help of the "Init" parameter. In the factory setting ("Init" parameter = ERR),
the output relays switch to the fault state until completion of the initialization phase because
there is no valid measuring result of the fault current.
If the parameter is set to "OK", it is assumed that there is no internal fault and the fault current
will be within the set limits. For this reason, the output relays are switched to the work position
when the supply voltage is present.
After completion of the initialization phase, a permanent self-test takes place without
interrupting the monitoring function.
Restart delay time
If autoreset is activated on the monitoring relay, the restart delay will start as soon as the
measured value to be monitored reenters to the correct range after an overshoot or undershoot.
The associated hysteresis threshold is taken into consideration here. At the end of this time the
contacts switch back to normal operation.
SIRIUS 3UG4 / 3RR2 monitoring relay
Equipment Manual, 07/2021, NEB927043002000/RS-AD/005
Parameters
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