Symbol 6181 from IEC 60417 - Title/Meaning: Separate supply unit Function/description: To indicate that a specific separate supply unit is required for connecting electrical equipment to the supply mains.
Additional information: 
See aslo IEC 60417-5926: Polarity of d.c. power connector.;It may have wider application.
Own work using: iso.org/obp/graphics/grs/b9c89dca-35ac-42d8-aec4-99d9564be2c3 200.png
Vectorization:  Mrmw