User Manual

Parameters
3UG4 / 3RR2 monitoring relays
356 Manual, 02/2013, NEB927043002000/RS-AA/002
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.
7KUHVKROG
IRU
RYHUVKRRW
7KUHVKROG
IRU
XQGHUVKRRW
&RUUHFWUDQJH
1RUPDOUDQJH
0HD
VXUHG
YDOXH
+\VWHUHVLVWKUHVKROG
IRUWKH
WKUHVKROGIRU
XQGHUVKRRW
+\VWHUHVLVWKUHVKROG
IRUWKH
WKUHVKROGIRU
RYHUVKRRW
+\VW
+\VW

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
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.
The restart delay time permits motor cooling if the device has tripped due to a temperature
rise.
Possible indications on the display: RsDel
Blocking current monitoring
If the load current overshoots the value of the set threshold for overshoot (I▲) by a multiple of
n during operation, a blocking current error has occurred. The tripping delay time that is
running due to the current threshold overshoot is stopped and the outputs are switched.
Indication on the display: n x I▲