Working schematic diagram of magnetic card ammeter

Working principle of magnetic card ammeter

Simply put, the magnetic card prepaid watt-hour meter is an intelligent watt-hour meter that uses magnetic card as the data transmission medium of electric energy value, and adds functional modules such as load control part into the watt-hour meter (electronic watt-hour meter or mechanical watt-hour meter) to realize electricity meter reading and settlement.

Classification of magnetic cards: Magnetic cards are also called ic cards.

1. According to different chip types, IC cards can be roughly divided into three types: memory card, logic encryption card and CPU card.

2. According to the form of embedded integrated circuit chips, IC cards can be divided into contact cards and contactless cards.

Three. Magnetic card electric meter consists of electricity sales system management, magnetic card, card reader and magnetic card electric meter.

Four. Development status of magnetic card watt-hour meter in recent years

Before 1995, it was mainly electric key magnetic cards, and 93C46 and 24C0 1 magnetic cards were erasable memory chips (EEPROM) or universal memory cards. Magnetic cards are easy to store, simple to use, low in price and low in security, and may be cracked. Users are mainly property communities.

1995- 1999 mainly refers to telephone cards and magnetic cards, mainly memory cards (24C0 1) and logic encryption cards (4442, 4428). The security of logical encryption cards (4442, 4428) is further improved. The embedded chip adds control logic outside the storage area, and the password needs to be checked before accessing the storage area. Only when the password is correct can it be operated. Users expanded from simple property communities to power industry management departments, and began to be widely used.

From 1998 to now, it is mainly a financial magnetic card. The embedded chip of CPU card (CPU card and SAM module as encryption media) is equivalent to a special type of single chip microcomputer. Besides the controller, memory and timing control logic, it also has the characteristics of large storage capacity, strong processing ability and safe information storage. Take the lead in the comprehensive promotion in Beijing Power Supply Bureau, and start to promote in Henan, Hunan and other cities.

Magnetic card prepaid watt-hour meter brings great convenience and benefits to the charge and meter reading of power department, and also brings profits to manufacturers; As an IC card prepaid watt-hour meter manufacturer, we should fully absorb many thoughts brought by this case, actively reflect on ourselves, prevent delays, actively eliminate defective products, and be responsible for the enterprise itself, the industry development and the society! * * * Maintain the healthy development of the electric energy meter industry!

Verb (abbreviation of verb) features:

(1) does not need manual meter reading, which is beneficial to modern management. The use of IC card electric meter avoids many inconveniences brought to customers by manual meter reading and door-to-door charging, and can save historical electricity purchase data for the convenience of customers.

(2) It fully embodies the commodity attribute of electricity. With the implementation of buying electricity before using it, customers can purchase and use electricity in a planned way according to their actual needs, and will not incur late fees and increase unnecessary expenses due to arrears.

(3) The problem of difficult charging is solved. It can well solve the charging problem of scattered resident customers, temporary electricity customers and customers who often owe money.

The magnetic card electric meter has many anti-stealing functions, such as small starting current, no creep, wide load, low power consumption, flat error curve, good long-term operation stability, beautiful appearance, small volume, light weight, convenient installation and so on.

High precision: all-electronic design, built-in imported special chip, accuracy is not affected by frequency, temperature, voltage and higher harmonics.

Long life: SMT technology and optimized circuit design are adopted, and the whole machine does not need to adjust the circuit after leaving the factory.

Low power consumption: low power consumption design is adopted to reduce the line loss of power grid.

Pre-purchase electricity; The magnetic card transmits data to read back the data, including: reading back the total power, remaining power, cumulative power purchase in the table, total power purchase times and other information.

Store table constants, initial values, user addresses, names and other information.

Overload alarm, power outage and remaining power alarm to remind users to buy electricity in time.

Technical parameters: Long-life matrix is adopted to extend the service life.

I. Introduction of IC card watt-hour meter:

There are many schemes to transform the old electromagnetic watt-hour meter, one of which is data acquisition; The other is a data card (IC card or magnetic card). The data acquisition method is to transmit the electricity consumption in the electric energy meter to the electric power bureau by wireless or wired; This system costs a lot, and it is widely used in some developed countries. The data card mode uses the card as the medium of data transmission, which is more suitable for the situation in China. Among them, IC card (electronic card) and magnetic card have the same size, but the media for recording data are different. There is a magnetic tape on the magnetic card, and the data is recorded in the same way as a tape recorder. Both recording and reading data require head movement. IC card encapsulates integrated circuit (memory) in plastic substrate, and data recording and reading are completed by CPU chip. The advantages of IC card are (1) large amount of information, encryption and high reliability; (2) the information is kept for a long time and is not easy to be destroyed (the magnetic card can be demagnetized under an external magnetic field); (3) It can be reused; (4) Low cost.

2. Card watt-hour meter charging system:

Microcomputer management system card vending machine IC card watt-hour meter

The microcomputer and card writing machine are managed by the electricity selling unit (electric power bureau). When the user holds the card, he/she first goes to the electricity selling unit to buy the required electricity (kWh) in cash. After returning home, he inserted the card into the card holder (CPU chip) of the electricity meter, and then the user could use the electricity. When the electricity recorded by the user's electricity meter is still 10 degrees, he will give the user a warning (such as power failure) to remind the user to buy electricity again. If the remaining power of the meter is zero and the new power is still not replenished, the relay in the meter is disconnected and the power supply is stopped.

3. Technical index of electric meter: (in line with IEC 1036 and JB/T8382- 1996 standards)

(1) technical indicators:

A. Current range: 5 (20) A, 10 (40) A.

B. Instrument constant: 1600 imp/kW, h

C. Starting current: 0.4% IB

D. Working rate: less than 2W

E.IC card: encryption can be reused.

F Other functions: 4-digit display, alarm function, data writing and bidirectional counting.

G. Service environment: -20℃ ~ 45℃

H. volume:154mm×110mm× 63mm.

I. Weight: 0.7 kg

4. Main structure and working principle:

The shell of the watt-hour meter is made of flame-retardant ABS plastic, and the terminal is made of phenolic resin. All components are mounted on PCB and displayed by 4-bit led.

The electric meter consists of two main functional blocks: one is the electric energy metering part, and the other is the microprocessor part. The electric energy metering part uses a single-phase electric energy detection special integrated circuit to generate a pulse sequence proportional to the electricity consumption and then send it to the microprocessor management system; The electric quantity data on the electronic card is directly sent to the microprocessor management system through the electronic card, and finally the CPU provides the display and alarm relay after calculation. Status signal.

5. Main functions:

(1) power card

The electric energy card adopts EEPROM technology with single power supply, one meter and one card system, which is not universal for users. The data is encrypted many times after writing back, and the ic card can be reused.

(4) Call the police

When the user uses electricity, the power in the watt-hour meter will count down. When the remaining power in the meter is equal to the alarm power (the alarm power can be preset to 0 ~ 99 degrees according to the different situations of each power bureau), the power will be cut off once, and the user needs to insert a power card to restore power supply.

(5) Power failure

When the remaining power in the watt-hour meter is zero, the watt-hour meter is automatically turned on and the power supply is interrupted until the power card with effective power is inserted.

8) Anti-theft function

When the remaining power is zero, the relay trips, and the user short-circuits the relay, the electricity meter records the abnormal time of power consumption, and writes it back to the power sales system when the user buys electricity next time, so that the power management department can handle it accordingly. This meter also uses a two-way recording chip to prevent power theft caused by reverse connection of incoming and outgoing lines.