12 ABB SACEConstruction and functional characteristicsTypical units and cross-sectionsThe ABB MNS R switchgear is de-signed for the installation of ABBEmax air circuit-breakers as well asABB Tmax and Isomax moulded-case circuit-breakers, in all the avail-able versions, fixed, plug-in and with-drawable. It allows installation of themain ABB apparatus and of themeasuring and protection instrumentsavailable on the market, according todifferent design requirements.Construction solutions with ABBEmax air circuit-breakers and ABBIsomax and Tmax moulded-case cir-cuit-breakersEmax air circuit-breakers panels areavailable with both top and bottomentry design.For modules sizing, please refer to ta-bles at page 15.Tmax and Isomax moulded-case cir-cuit-breakers are installed horizontallyand vertically as well in the unit.For modules sizing, please refer to ta-bles at page 14.The bus-duct can easily be connected to the busbarsystem of the circuit-breakers in the switchgear.Typical realisation of a structure with Emax circuit-breakerconnected in the top part to a bus-duct.Typical section with two superimpo-sed Emax air circuit-breakers. Thecircuit-breaker placed in the bottomis an incoming/outgoing feederthat can be provide with cable aswell as bus-duct connection.The circuit-breaker placed on topof the feeder is a bus-tie andit connects the two mainbusbar systemsThe switchgear allows the installation of bus ducts with various current carrying capacities