It is used for protection of electric shock and fire risk. When human gets an electric shock or current leakage of electric network exceeds the specified value, the breaker can cut off the fault power supply within quite short period of time to protect human beings and electric appliances. CXL3 is electromagnetic type: earth leakage with no need of auxiliary power supply, especially used in domestic, third industry and miniature industry application with function of isolation. Standard: IEC61008-1.