It is consists of Residual Current Monitor, residual current detection module，temperature detection module, over-current detection module and the detection modules are optional for different monitoring and protecting functions. The Residual Current Monitor is installed in built-in type. By mounting the detection module onto the distribution box, it can detect signals of residual current, over-current and temperature then display relevant values real-time on the screen. It is quite convenient for network forming. By adding different detection modules, different protecting functions can be achieved. It is suitable for new or reconstruction projects for being small in size, convenient to fix in and also economic.