IEC 60947-3-2020 LOW-VOLTAGE SWITCHGEAR AND CONTROL GEAR – Part 3: Switches, disconnectors, switch-disconnectors and fuse-combination units.
3.3 General terms
3.3.1 disconnector
mechanical switching device which, in the open position, complies with the requirements specified for the isolating function
Note 1 to entry: A disconnector is capable of opening and closing a circuit when either a negligible current is broken or made, or when no significant change in the voltage across the terminals of each of the poles of the disconnector occurs. It is also capable of carrying currents under normal circuit conditions and carrying, for a specified time, currents under abnormal conditions such as those of short-circuit.
[SOURCE: IEC 60050-441:2000，441-14-05， modified – Reference to isolating function instead of isolating distance.]
3.3.2 fuse-combination unit
combination of a mechanical switching device and one or more fuses in a composite unit,assembled by the manufacturer or in accordance with his instructions
[SOURCE: IEC 60050-441:2000, 441-14-04, modified – The note has been deleted.]
3.3.3 switch-fuse
switch in which one or more poles have a fuse in series in a composite unit
[SOURCE: IEC 60050-441:2000, 441-14-14]
3.3.3.1 switch-fuse single opening
switch-fuse which provides an interruption in the circuit on one side of the fuse-link only
Note 1 to entry: With this arrangement, safety precautions may be necessary when removing fuse-links.
3.3.3.2 switch-fuse double opening
switch-fuse which provides an interruption in the circuit on both sides of the fuse-link
Note 1 to entry: With this arrangement, safety precautions may be necessary when removing fuse-links.
3.3.4 fuse-switch
switch in which a fuse-link or a fuse-carrier with fuse-link forms the moving contact
[SOURCE: IEC 60050-441:2000, 441-14-17]
3.3.4.1  fuse-switch single opening
fuse-switch which provides an interruption in the circuit on one side of the fuse-link only
Note 1 to entry: With this arrangement, safety precautions may be necessary when removing fuse-links.
3.3.4.2 fuse-switch double opening
fuse-switch which provides an interruption in the circuit on both sides of the fuse-link
Note 1 to entry: With this arrangement, safety precautions may be necessary when removing fuse-links.
3.3.5 disconnector-fuse
disconnector in which one or more poles have a fuse in series in a composite unit
[SOURCE: IEC 60050-441:2000, 441-14-15]
3.3.5.1  disconnector-fuse single opening
disconnector-fuse which provides an opening in the circuit on at least one side of the fuse- link, that satisfies the requirements specified for the isolating function
Note 1 to entry: With this arrangement, safety precautions may be necessary when removing fuse-links.
3.3.5.2 disconnector-fuse double opening
disconnector-fuse which provides an opening in the circuit that satisfies the requirements specified for the isolating function on both sides of the fuse-link
3.3.6 disconnector in which a fuse-link or fuse-carrier with fuse-link forms the moving contact
[SOURCE: IEC 60050-441:2000, 441-14-18]
3.3.6.1 fuse-disconnector single opening
fuse-disconnector which provides an opening in the circuit on at least one side of the fuse-link that satisfies the requirements specified for the isolating function.IEC 60947-3 pdf download.