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Keypad Meter Prepayment Vending System


Special Declaration
Copyright ©Shenzhen HEXCELL. All Rights Reserved
Shenzhen HEXCELL Co., Ltd has been adopting the policy of sustainable product improvement. Therefore, the company reserves the right to change product operational details and specifications and may change the contents of the manual without any notice. No part of the manual shall be allowed to be reproduced or spread in any form by any means for any purpose by any person or any other company without permission in written form from Shenzhen HEXCELL Electronics Technology Co., Ltd.
Trademark Declaration
(Trademark of HEXCELL) and other HEXCELL logos are trademarks of HEXCELL.
Other trademarks mentioned in this document are possessed by their respective owners.
Keypad Meter Prepayment Vending System
1.1 System Introduction
Keypad Prepayment Vending System meets the STS standard. It follows IEC 62055-41 communication protocol, adopts 20 digit Encrypted number for data carrier to transfer purchase information to meters. It has diverse ways to purchase electricity: Vending station, Mobile vending, Internet online vending, SMS, ATM, etc.
1.2 System Characteristic
• Storage management.
• Customer information management.
• Power vending.
• Refund management.
• System parameters management (Price, tax rate).
• Vending station credit limit.
• History arrear management.
• Data interface for other billing system.
• Setting for report format.
• Meter reading management.
• Token management.
• Security module management.
• Security files management.
• Operator management.
• Many kinds of language support (Independent language files).
1.3 System Framework
 Keypad Prepayment Vending System has two different versions: C/S (Client/Server) framework vending system and B/S (Browser/Server) framework vending system.
• For C/S framework vending system, it does not need high-level hardware and network service. As to data transfer from Client vending station to database server, it supports via USB flash or E-mail. This solution is the economic way at first stage.
• For B/S framework vending system, it needs high-level hardware, stable network service and devices for safety. The cost for B/S is higher than C/S at the first stage, but offers advantages to maintenance.
Customer can choose different system upon demand.
1.4 System (B/S framework) Structure
Servers Applicable:
• Database Server: used for storage of business data;
• Web/Time task Server: used for providing HTTP service to connect vending points of utility company, and connection for bank payment collection, internet power vending, vending agency, etc;
• Vending station: customer purchase energy server point.
• Offline / online vending station: Mobile vending device.
Notice: Above‐mentioned server application can be grouped according to customer demand and development condition; all service function operated in one server is supported as well.
1.5 System (C/S framework) Structure
Other Systems:
Power marketing and its business system;
Telecommunication port: payment collection port provided by bank for ATM automatic and internet power vending;
Other System port: payment collection through agents like Network Company, Telecommunication Company or scratch card.
1.6 System Compatibility and Scalability
 Keypad Prepayment Vending System adopts unified power vending and revenue collection method, compatible with various IC prepayment energy meters, STS keypad prepayment energy meter, SMS prepayment energy meter researched by HEXCELL Electronics, as well as STS keypad energy meter made by different manufacturers. Meanwhile, it makes  compatible with prepayment energy meter with different type and different protocol, prepayment water meter, prepayment hot water meter and gas meter by 
system’third party extended interface base.
1.7 Diversified Power Vending Module
 Keypad Prepayment Vending System provides various vending modes in order to bring convenience and efficiency to users and reduce workload of vending personnel.
Users purchase electricity from ATM self-help equipment. Recharge will be made by connecting with bank system after safety certificate. ATM will read the card and print digit code.
• PC recharge
Users enter online network vending website to purchase electricity(IC card reader is needed for operation for IC prepayment energy meter). After paying and confirming the payment on internet, vending management center will make safety authentication and give vending instruction for printing digit code.
• POS, PDA recharge
Users enter network vending website by internet with handhold computer for recharge (It cannot recharge for IC prepayment energy meter).
• Agent vending
Banks or other agent vendors authorized by the utility provide vending business for users.
• Recharge hall
Integrated petty charges recharge hall provide electricity vending business.
• Vending hall
Power supply system provides internal vending network.
• Scratch card
Telecom companies use their value added service to transfer the recharge payment and give recharge instruction (It cannot recharge for IC prepayment energy meter).
Telecom companies use their value added service to transfer the recharge payment, and after successful recharge transferring, recharge can be made by SMS. It is applicable for SMS prepayment energy meter and STS keypad prepayment energy meter (It cannot recharge for IC card prepayment energy meter).
1.8 System Main Functions
Keypad Prepayment Vending System has three versions: standard version, professional version and enterprise version. Different version system contains different functions and supports different meter type. Customers can choose according to their actual business requirement.
has following function modules:
• Daily business processing module
Customer data maintenance, power consumption contact signing and canceling, petty charge collection, power vending, meter exchange, card complement, card data maintenance, and complementally bill printing.
• Power vending network management module
Contact signing or canceling of vending network, vending terminal management, vending network reconciliation, vending network permission, commission payment, etc
• Tempering module
Customer power off/power recovery, tempering charge collection, handling charge collection of power off made by customers, etc
• Charge collection module
Petty charge collection, capacitance increase charge collection, meter freezing charge collection
• Reports outputting module
Account opening integrated report, vending integrated report, consumption integrated report, tempering integrated report, vending network integrated report, charges integrated report, etc daily report outputting, consumption and vending and other analyses report outputting.
• System management module
Company information management, department management, role permission management, user management, electricity price management, system operation data management, data management, data maintenance, data exchange management, etc,
• Assistance module: 
Online assistance display. 
2 Keypad Prepayment Meter
2.1 Executive Summary
The system consists of two parts: The prepayment Electricity Vending Management System and Prepayment meters. 
Prepayment meter is a kind of meter which requires the consumer to pay for the electricity they are to use in advance. The consumers are required to charge the electricity they have purchased into the meter through some intermediary, and the meter shall identify and process the data and then supply electricity to the consumer accordingly. When the credit in the meter is small (equal or below the warning amount), then the meter will send out a warning signal to the consumer to remind them for charging; when the credit in the meter is zero already, the power supply shall be cut off, realizing the principle of “Prepayment”.
The application of the prepayment meter can successfully solve such practical problems as inaccurate meter manual reading and difficult in collection of the electricity fee which the Electricity Management Authority are faced with nowadays. Following are the prepayment meter products developed and manufactured by Shenzhen HEXCELL Co., Ltd.

Keypad Prepayment Meter

2.2 Keypad Prepayment Energy Meter
Keypad Prepayment Energy Meter is a prepayment meter using virtual intermediary, i.e. token, as data exchange media.
Token means a code consists of 20 digits, such as 2837 5872 3731 6854 3423. After the consumer makes the payment of the electricity, a unique token shall be generated by the Vending Management System. Then the consumer is required to input the token into the meter through the keypad on the meter to realize the credit transfer. (The meter shall decode the token according to the communication protocol).
2.3 Applicable Standards on Keypad Prepayment Meter
The only international standards available for the prepayment metering system is IEC62055, which was drafted by Standard Transfer Specification Association (STSA) established in 1997 in South Africa and recognized as an international standard, i.e. IEC62055 in 2005.
IEC62055 series of standards covers payment collection management system, CIS customer information system, vending management system, data transfer carrier, data exchange standard, prepayment meter, interface standard and other related contents, all of which establishes a complete system frame work for Prepayment Metering System.
IEC62055 series of standard consist of:
EC62055-21 Standardization structure
IEC62055-31 Prepayment meters for Active Energy (Class 1 and 2)
IEC62055-41 STS standard data transferring protocol-Application layer data transferring protocol
IEC62055-51 STS standard data transferring protocol—physical layer data exchange carrier (numeric and magnetic card carrier)
EC62055- 52 STS standard data transferring protocol—physical layer data exchange carrier (communication virtual carrier)
As all the keypad prepayment meter follows the same standard, certified for their compatibility with STS standard, and adopts standardized security module encryption algorithm), all prepayment meters and vending system manufactured by different manufacturers are compatible with each other.
As STS (Standard Transfer Standard) has been the only open prepayment metering system standard all over the world, and only with the authorization by STSA can the technology be used, the safety and security of the Electricity Utilities are assured in the use of the STS system.
As to obtain the compatibility, the keypad prepayment meter products of Shenzhen HEXCELL Co., Ltd. are all STS certified and the manufacturer’s code is “54”.
Apart from the STS standard, HEXCELL’s keypad prepayment metering products also comply with the Following standards:
IEC 62052-11 2003 General requirement for Electricity measurement equipment (AC) test and test conditions, part 11, measuring equipment.
IEC 62053-21 2003 Special requirement on Electricity measurement equipment(AC),
Part 21, special requirement on static active electricity meters (class 1 and 2)
SANS 1524-1 2005 National Standard of South Africa for prepayment meters (SABS certification)
ESKOM SCSSCAAA9 Prepayment meter technical requirement of ESKOM, South Africa
ESKOM TRMSCAAP2 Prepayment meter technical requirement of ESKOM, South Africa
BS 5685 British Standard type of wire connection
DIN 43857 Deutsch Standard type of wire Connection
IEC60529 2001 Meter casing protection class
2.3.1 MCU
MCU (Measurement and control unit) is the main body of the meter: single/three phase integrated/split keypad Prepayment energy meter. It is installed outdoors and the installation complies with meter installation requirement and supports RS485/M-bus communication, infrared communication, Power Line Carrier Wave Communication (PLC) and RF (Radio Frequency) communication.
MCU can adopt LCD display to display all measured data such as accumulative kWh reading, history monthly kWh consumption, credit charged, credit balance, load profile, warning/alarms.
Through different communication means, MCU can also be programmed for it operation parameters or switching tariffs under stepped multi-tariff arrangement.
2.3.2 UIU
UIU is User Interface Unit used for single phase, three-phase split keypad prepaid energy meter. It is installed indoor, which is convenient for the user to learn the meter operation parameters and load the pre-purchased energy (credit).
2.4 Technical Features
The main reason for the wide acceptance of STS keypad prepayment meters lies at the salient technical features of the virtual token data transferring system.
2.4.1 Features of STS
• STS is a prepayment technology for data exchange and communication transferring based on virtual token which fits the development trend of the future communication technology.
• STS data transfer standard is used to define the process of transferring available credit to electricity meter; it can also be adopted in water meter, gas meter and other utility meters;
• STS is a secure communication system which is used for the data exchange between vending point and meter;
• STS is an open and secured worldwide transferring standard. It adopts IEC 62055-41 as the only international standard for prepayment system;
• Encryption key technology is provided (provide leveled encryption keys which are managed by Utility themselves);
• Every TOKEN, meter, vending point and prepayment metering system are protected by different levels of security control;
• The encryption system is reliable and technically reduces the possibility of being attacked;
• Multi-system structure ensures its timely technical updating;
• Products in the standard system have to obtain the STS certification;
• Transferring process of charging token in the system is secure and reliable. Even in case of repeated transferring, meter will accept the data only once; and the information is only for valid for the assigned meter for it contains the information of the meter.
• More than 20 million STS prepayment meters have already been installed and used by hundreds of Utilities all over the world;
• The use of STS ensures the compatibility between meters manufactured by different manufacturers; Utility can purchase products from any STS certified manufacturer or vending system supplier freely without any concern with the security of the system.
2.4.2 Features of keypad meter
• STS certification
• 20 digits of virtual token
• Support TOU (Time of use) and Stepped tariff function;
• Multiple credit balance alarm (local warning, Short message service and email);
• Overload disconnection/load control;
• Emergency overdraft function and friendly non-disconnection function
• Anti-stocking of credit function;
• Build-in RS485 or PLC communication module, support remote charging;
• Once remote charge fails, also support local keypad charging and infrared communication;
• Meter is installed in meter box, consumer cannot and need not to touch meter;
• Build-in reliable relay, support relay failure detection and warning;
• Anti-tamper function;
• Consumer consumption history information inquiry;
• Easy to adopt split type design.
2.4.3 Flexible Credit Purchase Means
• SMS self serviced credit purchase;
• Credit purchase via internet;
• Vending station purchase;
• Scratch card purchase;
• Credit charging via Convenient store POS machine;
• Credit purchase via purchase of charging card;
• Self-serviced credit purchase via internet banking;
• Credit purchase via Call center/special service telephone number;
• Credit purchase via ATM
2.5 Categories of HEXCELL Keypad Prepayment Meter
Based on phases of consumer:
• Single phase keypad prepayment meter
• Three phase keypad prepayment meter
Based on installation method:
• Single phase integrated type prepayment meter;
• Single phase Split type prepayment meter;
• Three phase integrated type prepayment meter;
• Three phase Split type prepayment meter;
Based on the standards the meter comply with:
• IEC standard complied, BS5685 wiring or DIN43857 wiring single phase integrated type prepayment meter, single phase split type prepayment meter, three phase integrated type prepayment meter and three phase split type prepayment meter;
Installation diagram of integrated type keypad prepayment meter:
Installation diagram of split type keypad prepayment meter:
2.6 Basic Function of Products
Keypad prepayment meter products series of HEXCELL adopt advanced technology of measurement, control and communication. They can provide not only accurate measurement of energy, but also reliable control on the collection of electricity charges. HEXCELL’s keypad prepayment meter products (including single and three phase keypad prepayment meter, MCU & UIU etc.) have the following basic functions:
• 20 digits TOKEN comply with STS specification;
• Measurement, calculation and storage of active energy, Reactive energy (for three phase meter), apparent energy and related parameters (voltage, current, frequency, demand, power);
• TOU (time of usage) function: support programmable tariff scheme;
• History data storage function: can store data of the last 12 months;
• Event record function:can record event such as terminal cover open, meter cover open, power loss, phase loss, tariff change, meter date/time calibration, MD reset, battery replacement and external magnetic influence;
• Anti-tamper function:can detect and record tamper behaviors such as reverse current and circuit bypass;
• Load control function: for different types of consumers, different load control threshold can be programmed to control their consumption;
• Visible/audible Low credit balance (in energy units/in monetary units) warning signal.
• Overdraft electricity switch;
• Minimum charity electricity consumption (basic electricity use) function;
• Disconnection disable function at night (or predefined periods), in holidays and weekends 
• Peak hour load control facility;
• IP54 protection provided for outdoor-use MCU and IP51 protection provided for indoor-use UIU;
• Large size, wide visible angle, wide working temperature range LCD screen with backlight
• Display items programmable
• Braille characters and key stroke tone provided on keypad
• Load threshold programmable
• 15 years life
• STSA certified
3 Single-phase Prepayment Keypad Meter
3.1 Summary of DDSY1398 single-phase keypad prepayment meter
Single-phase keypad prepayment energy meter 
Main Application
DDSY1398 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 keypad interface, which is used for active energy metering & prepayment controlling. Besides the meter also has Infrared communication, RS485 or RS232 communication, metering element, real time clock unit, load control switch and other auxiliaries.
3.1.3 Additional functions
1.Reversed consumption is measured as forward one 
2.With demand calculation 
3.Realizing load detection and control function of power consumers 
3.1.4 Main functions
1.When the residual energy is 0 or the allowable overdraft that both sides agreed, this meter will send out   power-off signal to have load switch cut off power. The power will be recovered automatically after inputting new purchased energy amount. 
2.With self-test function 
3.With event recording function (including cover-opening event, tamper event and power failure event) 
3.1.5 Main features
Prepayment mode of power consumption that is paying first, consuming later 
1.DDSY1398 model is a single-phase keypad prepayment energy meter using kWh as settlement mode. User purchases energy amount and meter will decrease the residual energy amount gradually. When the residual quantity is zero, meter will cut off power supply. When the residual energy is 0 or the allowable overdraft that both sides agreed, this meter will send out power-off signal to have load switch cut off power. The power will be recovered automatically after inputting new purchased energy amount.
2.This meter adopts STS algorithm(NRS 009-6-7,NRS 009-6-8, NRS 009-6-9)and a complete safety management system which is highly secured, and completely compatible with other STS certified systems. 
3.With function of anti-tamper that can prevent usual tamper methods
3.1.6 Normative references
IEC62052-11 Electricity metering equipment (AC)-General requirements,  tests and test conditions- Part11: Metering equipment 
IEC62053-21 Electricity metering equipment (a.c.)-Particular requirements-Part21:Static meters for active energy(classes 1 and 2)
IEC62055-31 Electricity metering -Payment systems-Part31: Particular requirements Static payment meters for active energy (class 1 and 2) 
IEC62055-41 Electricity metering-Payment systems-Part 41:Standard transfer specification (STS) - Application layer protocol for one - way token carrier systems
IEC62055-51 Electricity metering -Payment systems-Part51: Standard transfer specification (STS)-Physical layer protocol for one-way numeric and magnetic card token carriers
GB/T 17215-2008 National Standards of the People's Republic of China- a.c. static meters for active energy (classes 1 and 2)
This meter is tested, tested and accepted fully in accordance with the Technical Requirements of Single-phase Keypad Prepayment Energy Meter ofShenzhen Golden Square Technology Co.,Ltd..These are the basic requirements based on IEC62053-21 Static Active Energy Watt-hour Meter (Class 1 and 2) – Special Requirements, and GB/T17215-2008 Alternating Current Static Active Energy Meter (Class 1 and 2), and have been considered as enterprise standard with higher technical index due to its incorporating the industry characters.
3.2 Technical parameters of meter
Rated voltage Un 240V
Operating voltage range:(80%,120%)
Operating voltage range:  0.70Un~1.30Un   
Normally operating within this range 
Limit range of operation: 0Un~1.90Un 
No damage happens to the meter within the limit range of operation. When the meter displays normally, its metering function can be ensured but without assuring its metering accuracy class, meanwhile the load control equipment cannot work. After recovery of operating voltage, the meter works normally with no change of metering accuracy class. 
Current parameters
● Max Current Imax 60A
● Limit current of meter measuring technique (No degradation in accuracy) 72A          
● Limit current of meter heat parameters 80A
● Starting current of meter (0.4%Ib) 20mA
● Current with no load running 5mA
● Current range for meter measuring 20mA~60A  
● Frequent current specification 5(60)A
Frequency parameters
Rated frequency fn 50HZ
Use range of frequency: -5% fn~+5% fn

Self power consumption
● Power consumption of voltage loop: ≤1W  1.2VA
● Power consump0tion of current loop: ≤0.2VA
Metering accuracy of active energy
Metering accuracy of active energy complies with requirements of class 1.0 of IEC62053-21 
The control index of the ex-factory product complies with the internal standard of our company: class 0.5  
DDSY1398-- Percentage error limit for active energy (class 1.0) 
COSΦ=0.5 Active error range

COSΦ=1  Active error range

COSΦ=0.5    Active error range

Display mode of meter
DDSY1398 adopts digital display mode.
● Display type                          LCD of wide temperature range 
● Character size of data item displayed       over10*4.05mm (integer)
● Character digits of data item displayed      8 digits with 6 integers and 2 decimals
● Character digits of data item sign displayed  2 digits
● Programmable for setting data item to be displayed
Pulse constant of meter: 1600imp/kWh
Active check output of meter
This meter is equipped with dedicated pulse indicator (LED located on the meter’ nameplate) for testing active energy and pulse output terminal (located on the connection terminal) used for the photoelectricity isolation. In order to ensure the accuracy of meter when metering the active energy, for different current test points the quantity of pulse sampled for testing shall increase step by step with increment of the test current, and be properly selected from 1 to 8. The active energy pulse is output at rate expressed as meter constant.
This meter uses optical-coupler (5kV isolated voltage, 50V DC output, maximum current 50 mA) as energy pulse output. The two feet C and E of optical-coupler hang in the air without external power supply and no protection, so be careful when connecting. The maximum insulation resistance between coupler’s output and other loops of meter is 5 kV, as a result, even if coupler’s output terminal puncture occurs, meter’s metering and other control functions will not be affected. 
The energy pulse output of meter: highest frequency 12.5Hz,pulse width 80ms
Serial communication interface of meter 
Mode A
● Type                   Serial bi-directional communication interface                     
● Communication Baud rate  1200bps
● Application              Meter’s metering data reading and related data item setting 
● Data format 1bit start bit, 8bit data bit,1bit even bit, 1bit stop bit
● Mode                   Infrared communication
Mode B
● Type                   Serial bi-directional communication interface
● Communication Baud rate  2400bps
● Application              Meter’s metering data reading and related data item setting 
● Data format 1bit start bit, 8bit data bit,1bit even bit, 1bit stop bit
● Mode                   RS485 or RS232 communication
Operation environment of meter
Test of insulation properties
3.3Operating principle
The circuit consists of the measuring element which centralizes SOC single chip (inside it including   measuring module, real time clock and temperature compensation circuit etc.) and modules like measuring and main control circuit, memory circuit (consisting of memory chips), RS232/485 communication circuit, power-supply circuit, cover-opening checking, LCD display and audio reminding of customer information, infrared transmission and reception circuit etc. Current sampling adopts bi-circuit measuring anti-tampering way with manganin shunt and current transformer. Voltage sampling adopts resistive divider network. The calibration of meters is completed through software directly.
Operation principle diagram of DDSY1398 single-phase keypad prepayment energy meter
3.3.1 Structure
1- Nameplate; 2-LCD; 3-Warning indicator; 4-Pulse indicator; 5-Button; 6-Impulse testing port; 7-Seal screw of upper cover; 8-RS-485 communication interface; 9-Bottom Connection terminal cover; 10-Seal screw of connection terminal cover;11-Infrared communication port; 12-Cover-opening contacting point; 13-Upper cover;  14-Bottom case; 15-Hanging hook
3.3.2 Connection diagram
Connection as showed above:
1—Phase in
2—Phase out
3—Neutral in
4—Neutral out
Pulse connection (For details refer to 2.1 Data item number table of meter):
            6—input pulse
            6—output pulse
3.3.3 Weight and dimension of meter
External dimensions     227mm×120mm×52mm
Installation dimension    Height    130 mm
Width 80mm
3.3.4 Connection of meter
Connection wire: The connection wire is under the meter terminal block. After connect the wire to the corresponding hole of terminal, please screw down the terminal screws. See below picture. 
Auxiliary terminal connection: RS485 port and pulse output test port is within terminal cover. There are seal screws in the terminal cover that can prevent any illegal connection and other setting.
Connection diagram as below:  
2.4.1Symmetric(This meter is symmetric)
3.3.5 Protective class
The test is carried out with the prepayment watt-hour meter manufactured by*******Co., accordance with IEC60529-4. The test results are shown as follows (IP54):
3.3.6 Resistance to heat and fire
Resistance to heat and fire class: V0 (all the casing made out of heat-resistant and fire-retardant material)
3.3. 7Metering function of DDSY1398
The meter can measure the reversed energy as forward one, and measure the total active energy & store the data, and also measure the residual credit balance & store the data. Pulse constant and pulse interval are used to measure real time power and output the active check pulse; it is accumulated to total active energy and active consumption of each settlement month.
3.3.8 Active energy measurement
Active energy: unit kWh
● Active energy metering of DDSY1398 Single-phase Keypad Prepayment Energy Meter
Phasor drawing of correct connection:
Active power:
P=UI cos φ
Active energy measurement expressed as:
EP  =∫Pdt =∫UI cos φ dt
3.3.9Definition of active energy direction
The meter adopts concepts of forward and reversed energy defined from customer’s point of view.
○ Customer forward energy= the Power Supply Department’s output energy
○ Customer reversed energy= the Power Supply Department’s received energy
3.3.10 Measurement of active maximum demand
● Demand value measured in six digits, including two integers and four decimals.
Active maximum demand unit is: kW
● MD calculation method is programmable:
1. Interval calculation method 
2. Slip calculation method (default setting when ex-factory)
● MD calculation cycle is programmable: 
Unit: min
5/10/15/30/60 mins
● MD slip window time: 
Unit: min
Default: 1 min
The demand cycle should be integral multiples of the slip window, but no more than 15 times.
3.4. Function instruction of meter
3.4.1 Metering function
● Measuring total active energy consumption
● Reversed energy is calculated as forward one which will be accumulated to total active energy consumption.
● Demand calculation method is programmable to be set as slip or interval method;
Demand cycle programmable: 15 minutes, 30 minutes, and 60 minutes available 
Slip window time programmable: available for 1/2/3/5/6/12mins
The demand cycle shall be an integral multiple of (but not more than 15 times) the slip window time.
3.4.2 Load control function
● This meter can be programmed for load control threshold;
● If both current demand and current power are not less than the user load control threshold, the overload warning will be triggered (The audio & video warning light flashes). After duration of 5 mins, the meter will cut off user load and add 1 to actual overload power-off times in register, at the same time the “overload power-off” warning will be triggered. (When load threshold is zero, this function is of no use.);
● Where the meter powers off for overload, the power supply will be recovered by pressing the button, otherwise the power supply will not be recovered;
● If overload trip often happens, the user can visit Power Selling Department to apply for capacity enlargement or other relevant businesses, and then input the digit TOKEN to have the supply recovered.
3.4.3 Overdraft consumption function
● If this meter has set overdraft amount and the residual amount is 0, the overdraft consumption function will be started by pressing any button;
● When the overdraft amount is used up, the meter will send out control signal to have load switch cut off.
3.4.4.Prewarning consumption function
● This meter can be programmed for setting user prewarning threshold;
● When the meter’s residual amount is equal to prewarning threshold, the meter will start the audio & video warning function in a way of warning light flashing. When prewarning threshold is zero, this function is of no use;
● When the residual amount is equal to half of prewarning threshold, the meter will send out power-off signal to have load switch cut off automatically;
● Power supply can be recovered by pressing any button, till the residual amount is zero.
3.4.5 Data display on LCD of meter
1. Power purchase TOKEN is correct. It will be accepted and “accept” will be displayed.
2. Power purchase TOKEN is incorrect. It will be rejected and “reject” will be displayed.
3. When “old” is displayed, it means TOKEN is out of date.
4. When “used” is displayed, it means the TOKEN is a used one.
5. Overload consumption—When consumption load is over the load threshold being set, “over po” will be displayed and the power will be cut off within specified time.
6. It shows that energy consumption is 0.01kWh and displays item code 01.
7. It shows that MD in current month is 0.00kW and displays item code 02.
8. It shows the residual energy is 100.00kWh and displays item code 07.
9. It shows meter’s present power is 1.00kW and the display item code is 31.
10. Other display information please refer to “4.12.1 Prompts of meter” and “4.14.3”
3.4.6. Prepayment function
The Power Selling Management System will produce a 20 digits code (generated based on user’s information and purchase amount). After the user input this code via the meter’s keypad, meter will decrypt the code. After passing the encryption authentification, current purchase amount will be written into meter’s memory and added to the residual amount and stored; When overdraft consumption or abnormal consumption happens, the overdraft consumption amount or abnormal consumption amount will be deducted from the purchase amount and the residual amount will be stored in memory; When the user is consuming power, the meter will deduct the residual amount gradually according to corresponding conditions. When the power-off condition is met, meter will cut off power supply and when power supply condition is met, meter will connect to user load automatically.
The ex-factory meter will be registered after the Power Supply Department replaced encryption key system and registered user information. The registration operation assigns numbers and appoints a meter ID number to the user, which realizes one-to-one correspondence between the user and the meter. The initial purchase amount as well as the encryption key and other parameters will be written into the meter.
1. Display of meter’s ID: input “65” through keypad, then press Enter button, the meter will display 11 digits meter ID No. on LCD (in 2 screens) and this No. must be the same as User ID(used for power purchase).
● Power purchasing
When the residual amount is insufficient, the customer can visit the power vending office to purchase electricity. At vending office a 20 digits serial number (TOKEN) will be produced based on user information and purchase amount.
Power purchase method:
1) Visit the local power vending office;
2) Provide your meter ID to the operator;
3) Inform the operator the amount you want to buy and pay the bill;
4) Obtain a 20-digits TOKEN printed on your receipt.
● Power loading
User will input the 20-digits serial number via meter’s keypad. After passing encryption key authentification, meter will accept purchase amount and adjust the residual amount and cumulative purchase amount and then save the new residual amount into EEPROM. At the same time power amount loaded this time will also be displayed on LCD. 
Input purchase power TOKEN into meter:
1) Key in the 20-digits TOKEN via keypad;
2) Confirm the numbers on LCD;
3) If TOKEN is wrongly input, please use backspace to modify;
4) After inputting all the 20 digits, press Enter to confirm the TOKEN input;
5) If TOKEN is correctly input, LCD will display “accept” and the power amount purchased;
6) If TOKEN is wrongly input, LCD will display “reject”.
● Audio warning function
The meter is programmable for setting the duration of audio warning of audio and video warning in minute, up to 99 mins. When the audio & video warning happens, if no any operation by user (pressing button or inserting the card), the audio & video warning will disappear automatically when the duration setting is reached. Where the duration is set to be zero, the meter cannot perform audio & video warning.
3.4.7 Event recording function
● Tamper event detecting and recording
When power-off condition is met and meter will cut the power consumption load switch. If user steals power by short-circuiting the in-line & out-line of meter outside, the meter will detect this tamper event within 5 mins and display “STL”on LCD screen. If the tamper is ongoing for more than 1 min, the meter will add 1 to the tamper times and record the tamper occurrence time. After ending the tamper action, the LCD will not stop displaying “STL” until the tamper event is cleared.
● Cover-openning event detecting and recording
When the connection terminal cover of meter is opened, the meter will send out power-off signal to have load switch cut the power automatically. Here power supply cannot be recovered even if the connection terminal cover is fitted, unless the Power Supply Department input the special TOKEN after fitting the connection terminal cover.
3.4.8  Meter-reading function
The Power Supply Department can read meter by using Handheld Unit equipped with non-modulating infrared communication interface or COM interface.
3.4.9 Infrared communication function
The meter is equipped with non-modulating infrared communication interface, with which time checking and data reading functions etc. of meter will be fulfilled via Handheld Unit.
● Time check
The time checking by programming or broadcasting can be carried out with the meter via the communication interface. Programming time check requires access control, and the real time clock can be calibrated to any time (year, month, day, week, hour, min, sec); broadcasting time check can be carried out only once a day and the calibrated time must be within ±5 min of the time clock of the meter, otherwise, the meter will refuse this broadcasting time check.
● Meter’s data item reading 
The data items in the meter can be read via the communication interface, including the current power consumption data, the data relevant to current prepayment, the recorded data of the previous 12 months, time clock, and records of various events etc.
3.4.10 RS232/485 communication function
This meter is equipped with RS485/RS232 communication interface. It can realize meter’s data item reading and time checking of meter via the Handheld Unit with RS485/RS232 communication interface.
RS232/485 communication function is optional, but only one. Please note down your requirements when placing an order.
●Time check
The time checking by programming or broadcasting can be carried out with the meter via the communication interface. Programming time check requires access control, and the real time clock can be calibrated to any time (year, month, day, week, hour, min, sec); broadcasting time check can be carried out only once a day and the calibrated time must be within ±5 min of the time clock of the meter, otherwise, the meter will refuse this broadcasting time check.
● Meter’s data item reading 
The data items in the meter can be read via the communication interface, including current power consumption data, the data relevant to the current prepayment, the recorded data of the previous 12 months, time clock, and all the data items and records of various events, etc.
3.4.11 Self-test
The meter has a self-test function. It can test LCD and relay etc. and report the results directly of indirectly.
3.4.12 Prompts
● Prompts of meter:
OLD:TOKEN out of date