1, measuring chip: measuring range can reach more than 12 times; linearity: ± 0.2%; the use of models for the CS5460, ADE7755, ADE7751, ADE7758. 2, single-chip memory memory: a strong anti-interference ability of the United States imported microcontroller; United States Microchip US MOT, the Netherlands philips. 3, electrolytic capacitor: 105 ℃, not less than 4,000 hours, leakage current: <3μA; the use of models for Japan Rubycon or NCC capacitors. 4, the power device: to ensure long-term work in the 450V AC voltage; the use of models for the RC capacitor or R-type transformers ; with low power consumption. 5, varistor: diameter of not less than 20mm, the nominal voltage: 750V ± 10% or 820V ± 10%. 6, IC deck: Imported standard IC deck, the service life of more than 100,000 times. 7, Relay : Use 60A or 120A magnetic latching relay.