My first device -stove- was detected after 24 hours. It showed the stove was ob anf off for every 2 seconds. Is it right?
Heating devices do go on/off frequently. My electric oven, dryer, and electric kiln do that. Is this the cook top burner or the stove part? How fast they cycle depends on the specific device. If it is really 2 seconds, (and you can only tell that in the ‘now’ chart, not the bubble one), then it may be worth investigating. I would think that is an unusual short off cycle.
Maybe others how have electric stoves can comment.
My stove also cycles the elements on and off very quickly. Maybe not every 2 seconds, but certainly close to that. On mine, you can hear the thermal switch clicking on and off very faintly if you put your ear near it.
Did you confirm this correlates with the stove actually being on? If so, you’re almost certainly seeing the effect of duty cycling (sometimes also called ‘pulse width modulation’ although that’s a lot more common in electrical engineering circles)