Applications: DDSF870B single-phase electronic multi-rate kilowatt-hour meter is a kind of electric energy measuring meter, which adopts special integrated circuit and new technology of micro-electronics with SMT technic to manufacture. It can accurately and directly measure 50Hz active energy consumption from single- phase AC electricity net. The part of meter register adopts ADE7755 chip, throughout to collect loop signal from DC and AC current, conversion from electric power value to correspond electric power pulse signal, controling chip according to customers' programme period of time, taking different time period power pulse register into correspond rate, and complete the function of display and communication, thus achieving hours metering functions. Technical parameters: 1) Rated voltage: AC 220V, 50 / 60Hz 2) Specifications: 2.5(10)A, 5(20)A, 10(40)A, 15(60)A, 20(80)A, 30(100)A 3) Accuracy: Class1, Class2 4) Working temperature range: -25 - 55癈 5) Power loss: ≤2.0W 6) Starting current: ≤0.004Ib 7) Day time error: ≤0.5s/d 8) After power stop, the batteries keep ≥10 years 9) Period of time switch error: ≤1min 10) Executive standards: GB/T17215-2002, GB/T15284-94, and DL/T645-1997 Functions and features: 1) Circuit design of preventing electromagnetic disturbance, wide working voltage range, good reliability, high accuracy, low power consumption, long life, high accuracy, preventing from electricity theft 2) With function of measuring active energy in positive and reversed way, and register of total energy, tine energy, peak energy, level energy, off-peak energy and depositing the data 3) With 3 tariffs: peak energy, level energy, off-peak energy and 12 time periods 4) With infrared communication port and RS485 communication port, 2 communication ports are independent to each other 5) With a function of programming, it can program kilowatt-hour meter by infrared and RS485 port communication 6) Clock of the inside meter adopts hardware clock circuit, and has the temperature repair electric circuit ,the inside placing clock has calendar and time leap year switch automatically