Function symbols

Switching devices are classified according to Utilization Category, or Category of Duty, thus:-

FUNCTION
Making and breaking current	Isolating	Making, breaking and isolating
Switch	Disconnector	Switch-disconnector
Switch-fuse	Disconnector-fuse	Switch-disconnector-fuse
Fuse-switch	Fuse-disconnector	Fuse-switch disconnector
NOTE 1 - All equipment may be single-break or multi-break. NOTE 2 - Symbols are based on IEC Publication 60617-7.

It is important to note that the definitions do not indicate whether the device is capable of being isolated at both ends of the fuse. Where this is not the case, adequate marking of the line/load terminals is essential for safe use.

LINKS

The Impact of HV Fuse Design and Application on the Development of International Standards (PDF)

Current standards

Category of duty

Function symbols

Frequent and Infrequent Use