UR Circuit Breakers Altech UR Circuit Breakers are UL 1077-recognized supplementary protectors with B-, C-, and D-trip curves. These DIN-rail-mounted modules are available in 1-, 2-, and 3-pole variants as well as an add-on neutral pole option. Altech UR Circuit Breakers feature a 17.5mm width per pole and 10kA short circuit withstand capacity. Typical applications include sensitive electronics, power supplies, and appliance circuits.