Symbol 6280 from IEC 60417 - Title/Meaning: Bimetallic instrument Function/description: To indicate the thermal instrument in which the deformation of a bimetallic element (the materials having different rates of expansion due to a change in temperature), heated directly or indirectly by a current, produces the indication.
Additional information: 
IEC 60051-1 provides technical details.
Own work using: iso.org/obp/graphics/grs/db25ebd4-bf52-4426-b345-9dd612cb5a63 200.png
Vectorization:  Mrmw