In general hysteresis means - "a range" or "band width". As for as our RM22UA33* relay is concerned, it can be considered as the threshold for the reset function of RM22UA* series relay.
For example, in under voltage relay, if the under-voltage threshold setting is 50V and the hysteresis setting is 20% means - the relay will trip at 50V (with in the time delay) and it will reset at 50 + 10 V (20%) = 60V. So it will trip on 50 V not on 40 V.
The hysteresis is necessary for the relay to avoid continuous trip and reset.
If there is no hysteresis setting, the relay may trip at 50 V and reset at 51 V and again trip at 50V and reset at 51 V, it means a small fluctuation in voltage will create nuisance trappings.
For example, in under voltage relay, if the under-voltage threshold setting is 50V and the hysteresis setting is 20% means - the relay will trip at 50V (with in the time delay) and it will reset at 50 + 10 V (20%) = 60V. So it will trip on 50 V not on 40 V.
The hysteresis is necessary for the relay to avoid continuous trip and reset.
If there is no hysteresis setting, the relay may trip at 50 V and reset at 51 V and again trip at 50V and reset at 51 V, it means a small fluctuation in voltage will create nuisance trappings.
Released for: Schneider Electric India
