Switch disconnectors combine the properties of;
1. Disconnectors (isolation)
2. Load switches (short circuit making capacity).
The purpose of the isolating function of disconnectors is to cut off the supply from all or a separate section of the installation by separating the installation or section from every source of electrical energy for reasons of safety. Isolators must be capable of withstanding the passage of short-circuit currents and is assigned a rated short-time withstand capability Icw, generally for 1 second.
Load switches are mechanical switching devices capable of making, carrying and breaking currents under normal circuit conditions. A load switch may have a rated short-time withstand capability Icw, a short-circuit making capacity Icm, however it does not have a short-circuit breaking capacity (according to IEC 60947-1 and 60947-3). Short-circuit currents can be conducted Icm (high short-circuit withstand capacity), but not be switched-off.
Accordingly, switch-disconnectors do NOT offer breaking functionality and thus they do not have a breaking capacity. It only offers switching and isolation, on-load or off-load.
1. Disconnectors (isolation)
2. Load switches (short circuit making capacity).
The purpose of the isolating function of disconnectors is to cut off the supply from all or a separate section of the installation by separating the installation or section from every source of electrical energy for reasons of safety. Isolators must be capable of withstanding the passage of short-circuit currents and is assigned a rated short-time withstand capability Icw, generally for 1 second.
Load switches are mechanical switching devices capable of making, carrying and breaking currents under normal circuit conditions. A load switch may have a rated short-time withstand capability Icw, a short-circuit making capacity Icm, however it does not have a short-circuit breaking capacity (according to IEC 60947-1 and 60947-3). Short-circuit currents can be conducted Icm (high short-circuit withstand capacity), but not be switched-off.
Accordingly, switch-disconnectors do NOT offer breaking functionality and thus they do not have a breaking capacity. It only offers switching and isolation, on-load or off-load.
Released for:Schneider Electric South Africa
