ABB MNS R System Manual

Also see for MNS R: Installation manual

4 ABB SACEConstruction and functional characteristicsSwitchgear frameThe MNS R frame is based onmodular 2 mm thick still C sec-tions, pre-drilled at a pitch of 25mm. Each unit is based onmodular elements and consistsof:– circuit-breaker compartments– instruments compartments– busbar compartment– cable compartment.All compartments are meccani-cally segregated from the others.The switchgear is pre set foreasy extensions on both sides.EarthingThe switchgear is provided with acontinuous electrolytic copper earth-ing busbar, with a cross-section suit-able for the proper switchgear short-circuit rating and pre-set on bothsides for connection to the earthingnetwork.Are connected to the earthing busbar- all the metallic structures of the indi-vidual units;- all not live metallic parts of the cir-cuit-breakers;- all CTs and VTs secondary earthingconnections.All others not live metallic parts of theapparatus are connected to the earth-ing busbar by means of the unit me-tallic structure.The doors with apparatus installed areconnected to the structure by meansof flexible copper braids. All theground connections are made withscrews or bolts provided with grippingwashers.