The UR26-81 is a trip-free DC high-speed current limiting air circuit-breaker, single pole unit, bi-directional, with electromagnetic blowout, direct instantaneous over-current release, natural air-cooling and electrical operating system. The UR26-81 is used to protect propulsion and auxiliary equipments mounted on rolling stock and can be delivered enclosed in a special protective box for vehicle's underframe mounting. The UR26-81 is also used in DC traction substation to protect the feeder contact lines and thrid rails as well as for insulation of defective line sections. The UR26-81 is also used for various industrial applications.