This standard specifies: a) the characteristics of SMCB; b) The conditions that SMCB should meet in the following aspects: 1. The operation and working conditions of SMCB during normal operation; 2) Operation and working conditions of SMCB under overload; 3) Operation and working conditions of SMCB under rated short-circuit capacity and below; 4) Dielectric performance of SMCB; 5) Selectivity of SMCB; c) The tests used to confirm that these conditions are met and the methods used in the tests; The data marked on the dSMCB; e) the test procedures executed during certification and the number of test samples submitted (see Appendix C); f) Under short circuit conditions, the SMCB is connected to the same circuit, followed by B that meets the requirements of GB 10963.1-2005, and the current limiting level meets the requirements of Appendix J, The coordination and working conditions of overcurrent protection circuit breakers (hereinafter referred to as MCBs) used in household and similar places with characteristics C; routine tests (see Appendix D. Note: "According to normal usage conditions" means that SMCBs are used in accordance with the manufacturer's regulations. This standard is applicable to AC 50 Hz or 60 Hz, with a rated voltage not exceeding 440 V (phase to phase) SMCB with a rated current not exceeding 125A and a rated short-circuit capacity not exceeding 50 000A. These SMCBs are designed to protect the line facilities and cables of buildings from overcurrent and similar purposes, and are designed for use by untrained personnel without the need for maintenance. SMCB is expected to be used in pollution level 3 environments. SMCB is suitable for isolation. SMCB should be able to meet the selective requirements of the front and rear overcurrent protection devices under the technical conditions specified in this standard. As long as it meets the requirements of IEC 60364-4-473:1997+A1:1998, the SMCB of this standard is also suitable for use in IT systems. For SMCBs with a protection level higher than IP20 in GB 4208-2008, as well as those commonly used in harsh environmental environments (such as excessive humidity, overheating, overcooling, or dust deposition) and hazardous locations (such as explosive prone areas), special structures may be required. The technical requirements for SMCB equipped with residual current protection devices (RCD) are being considered. The coordination between SMCB and fuse can be found in Appendix D and Appendix D. This standard includes all technical requirements necessary to ensure compliance with the operational characteristics required by type tests for such devices. This standard also includes details on test requirements and methods necessary to ensure the repeatability of test results