What is the purpose of this voltage monitoring relay?

[fubar.gr]

https://www.se.com/ae/en/product/RM17UAS15/voltage-control-relay-rm17u-range-65-260-v-ac/

Datasheet: https://download.schneider-electric.com/files?p_enDocType=Instruction+sheet&p_File_Name=S1A1959100_02.pdf&p_Doc_Ref=S1A19591

The datasheet describes two products, the one I'm interested in is the RM17UAS15, the first one.

It can be configured to detect overvoltage and undervoltage, but not both at the same time. It also has an adjustable hysteresis up to 20%. What is the reason for such a high hysteresis value? That means that if it is set for detecting an overvoltage of 260V, and the hysteresis set to 20%, if it is triggered it won't reset until voltage drops below 260-20% = 208 Volts, which is well below the nominal 230V.

In contrast, the other model in the datasheet, RM17UBE15 has a fixed hysteresis at a more reasonable value of 3%

[SteveThackery]

Isn't the hysteresis adjustable down to 5% though?  Mind you, I can't think why you would need a hysteresis bigger than the normal mains operating range, either.

Interesting how it insists it must not be used in safety critical applications.

[indeterminate]

Not everything runs on nice stable city mains electrical supplies
in rural settings and sites that run off local diesel generator supplies you can get huge voltage fluctuations as large loads turn on/off

Or you might just want a tel tail indicator at a site to show that there has been a over voltage event.