Ladder-type reference standard prepayment meter

GB / T 17215.321-2008 "AC measuring equipment - Specific requirements - Part 21: Static meters for active energy meter."
GB / T 18460.3-2001 "IC card  electric transformer  vending system Part 3: Pre-paid meter."
DL / T 645-1997 / DL / T 645-2007 " electric meter  energy meter communication protocol"
National Development and Reform Commission, "on the residential electricity price ladder guidance"