Symbol 6397 from IEC 60417 - Title/Meaning: Enlargement of the cooking zone, multiple circular Function/description: To identify an indicating or control element for the zone of three different cookware sizes.
Additional information: 
See also IEC 60417-5490, IEC 60417-5491,IEC 60417-5492, and IEC 60417-5493
IEC 60350-2:2017 Edition 2.0 (2017-08-30), Household electric cooking appliances - Part 2: Hobs - Methods for measuring performance
Own work using: iso.org/obp/graphics/grs/578a2905-9011-41fb-bbfb-e2ca37e66351 200.png
Vectorization:  Mrmw