Model DEM021MC three phase four wire electronic DIN rail active energy meter is a kind of new style three phase four wire active energy r meter, it adopt micro-electronics technique, and imported large scale integrate circuit, use advanced technique of digital and SMT techniques, etc. The meter completely accord with relevant technical requirements of class 1 three phase active energy meter stipulated in international standard IEC 62053-21. It can accurate and directly measure 50Hz or 60Hz active energy consumption from three phase four wire AC electricity net. This meter has seven digits LCD displays shows the active energy consumption. And there is a maintenance-free lithium batteries in it, it use for displaying power cut reading. It has following features: good reliability, small volume, light weight, specious nice appearance, convenient installation, etc. This meter has already got the patent certificate from China State Intellectual Property Office at present. Patent certificate NO. ZL 2006 3 0107349.1, any other country patent certificate are in assessing.