© Siemens AG 2010 BETA Protecting Miniature Circuit Breakers (MCBs) Miniature circuit breakers, 5SP and 5SY Overview MCBs are used to protect plants in buildings and for industrial applications. The devices can be used as main control switches for the disconnection or isolation of plants. The devices are approved for worldwide use according to IEC standards for systems up to 250/440 V AC. 60 V DC per pole is permitted in DC systems.
For industrial applications and in plant engineering, miniature circuit breakers can be supplemented with additional compo- nents, such as auxiliary switches, fault signal contacts, shunt re- leases, undervoltage releases, remote-controlled mechanisms and RC units. For North America, we also have additional certification accord- ing to UL 1077 for use as "supplementary protectors" in systems up to AC 480Y/277 V. For use in ship building, the devices also have numerous certifications according to shipping classifica- tions; BV, DNV, GL and LRS. For further information, please refer to the section "Configuration".
Benefits The infeed can be either from the top or the bottom as the ter- minals are identical. Clear and visible conductor connection that can be easily checked in front of the busbar. Large and easily accessible wiring space enables easy inser- tion of conductor in the terminal. Integrated movable terminal covers located at the cable en- tries ensure the terminals are fully insulated when the screws are tightened. The effective touch protection when grasping the device con- siderably exceeds the requirements of BGV A3 (labor safety specification). 19 Manual snap-on fixing and release systems that require no tools enable fast assembly and disassembly of MCBs.
Marked labeling field on all modular installation devices for uniform, quick and easy identification. The MCBs can be quickly and easily removed from the busbar assembly by hand if connections need to be changed. Time saving if parts need to be replaced because the busbars no longer need to be freed from the adjacent devices. 19/4 Siemens LV 1 · 2010