Smart single phase electricity energy meter

1 Overview
DDZY1277-STS is an active energy-metering instrument, using digital media as the data exchange medium. User will load the pre-purchased kWh, with settlement in terms of kWh. This meter is equipped with digital key  pad interface, which is used for active energy metering & prepayment controlling. Besides the meter also has Infrared communication and other auxiliaries.
Normative references:
l IEC62052-11 Electricity metering equipment(AC)-General requirements, tests and test conditionsPart11:Metering equipment
l IEC62053-21 Electricity metering equipment(AC)-Particular requirements-Part21:Static meters for active energy(classes 1 and 2)
l IEC62055-31 Electricity metering -Payment systems-Part 31:Particular requirements static payment meters for active energy(class 1 and 2)
l IEC62055-41 Electricity metering-Payment systems-Part 41:Standard transfer specification (STS)- Application layer protocol for one - way token carrier systems
l IEC62055-51 Electricity metering-Payment systems-Part 51:Standard transfer specification (STS)-Physical layer protocol for one-way numeric and magnetic card token carriersl

2 Solution
The solution is consist of MCU and CIU. MCU contains Management and Controlling Unit, Measuring chip, load switch ,memory circuit ,Infrared communication circuit ,power-supply circuit , LED indicator .CIU contains input unit (keypad ), alarm buzzer and LCD display Unit etc.
Current sampling adopts with manganin shunt. Voltage sampling adopts resistive divider network. The calibration of meters is completed through software directly.

3 Technical Parameters
3.1 Model Specification
Type:  DDZY1277-STS
Class:  1.0
Rated Voltage(Un):  240V
Frequency:  50Hz
Rated Current (Ib) :  5A
Max Current (Imax):  80A
Pulse Constant:  3200 imp/kWh
Starting Current :  0.4%Ib 20mA
Current range for meter measuring:  20mA~80A
Frequent current specification :  5(80)A
Operating Voltage Range:  0.60Un~1.2Un
Communication types: RS485 / Mbus / PLC / Optical
Dimension:  MCU:210*130*68 mm CIU:150*110*38 mm

4 Metering Function
DDZY1277-STS single-phase prepayment meter can measure forward and reverse active energy; and reverse active energy can be accumulated to the total consumption; measuring voltage and current; calculate total energy consumption; measuring last 12th months consumption; calculate the remaining credit; measuring instantaneous output energy etc.

5 Pre-payment Function
DDZY1277-STS single-phase prepayment meter can choose pre-payment and post-payment style. When the meter choose pre-payment type, this means the user need purchase firstly for the energy. The user need provide personal electricity account information and purchase for a token of 20 numbers at POS. Then inputting the token to the meter ,and generating relevant credit. The credit will decrease while user using electricity. When the remaining credit is low, the meter will remind the user. When the remaining credit is zero or negative ,the meter will disconnect the power supply through controlling relay switch.

5.1 Power purchase  
The lack of remaining credit, the user can go to the POS to purchase of electricity, the operating room based on user information purchase of electricity to produce a 20 sequence of numbers(TOKEN is).
Purchase of electricity by:
(1) go to the local electricity sales business hall.
(2) provide to the operator the ID number of the meter.
(3) tell the operator you want to buy electricity and pay.
(4) on the receipt, you get a printed token (20 digit code).

5.2 Charge
User entered the sequence of numbers in the meter by keyboard, After key authentication energy meter, the meter to accept the purchase of electricity from power, and adjust the remaining capacity and the cumulative purchase of electricity from power, and the remaining capacity value stored in EEPROM. and displays the installed electric power.
Single-phase Keypad Prepayment Energy Meter Purchase of electricity token input meter:
(1) in the meter by keyboard, enter the 20 tokens.
(2) the confirmation number on the LCD.
(3) If the token is entered incorrectly, please use the keyboard's "back button" to delete.
(4) All 20 input, press the Enter key to token confirmation.
(5) If the token input is correct, CIU will display the charging value for 2s, then display the total credit after charging.    
(6) If the token is entered incorrectly, the LCD will display "REJECT".

5.3 Overload Control:
If the current exceed 72A, the internal relay will be interrupted. CIU will display as “O|L”. The relay will be automatic closed after 30min.

6 Display Function
6.1  LCD display

When the meter is power on, the LCD will display the full screen as following, after several seconds the screen will display the normal information.

The means of the sign on the screen are:
1- credit level    2-reverse power   3-tamper indicator  4-power unit   
5-relay indicator  6-item number    7-number information

The data show that: six integers and two decimal places. The power unit kWh; active power unit(kW).
Credit level can be settled by the utility. different level will generate different alarm information to remain user.

6.2 Data display of meter
The 8-number data will display power information, billing information, token queue and remained information.
Total power consumption will display as six integers and two decimal places.
When typing in the 20-number token ,the screen will display t00he latest inputting number.

6.3 LED display
1- Credit: indicate the remaining credit is low  
2-Tamper:indicate the terminal cover is open
3- Pulse: Indicate power consumption rate