CN2300111Y - Cluster digital watt-hour meter - Google Patents

Abstract

The utility model discloses a cluster digital watt-hour meter, composed of a voltage sensor, a current sensor, an analog switch with a plurality of paths, a programmable operational amplifier, an analog to digital converter with sample holding, a CPU microprocessor system and a meter reader. The utility model also comprises a frequency measurement circuit and a meter value pulse output circuit. A power supply part comprises phase lacking of phase wires, a protection circuit, etc. Simultaneously, sampling for three-phase voltage can be realized to achieve three-phase electricity using balance. The cluster digital watt-hour meter of the utility model can measure electric power consumption of the arbitrary number of users. After processed by a computer, the electric power consumption can be displayed by the meter value pulse output circuit. Simultaneously, the infrared meter reader can realize automatic meter reading with the advantages of high measuring precision and low power consumption. The utility model can be connected with a central computer, realizing unified management of electricity usage.

Description

The concentrating type digital kilowatt-hour meter

The utility model relates to a kind of power department control, measures the measuring instrument of power consumption, relates in particular to a kind of concentrating type digital kilowatt-hour meter.

At present the watt-hour meter of the measurement electric weight that uses of power department and electricity consumer roughly has two classes: a class is that Every household has an ammeter, mainly contains two kinds of induction meter and electron watt-hour meters, because of establishing a table in a family, and the cost height, it is difficult to check meter, and can't be anti-electricity-theft; Another kind of is centralized watt-hour meter, though adopt the mode of centralized management, but still there is following shortcoming: 1. the disclosed a kind of centralized electronic electric meter of CN93243188.7 for example, only adopt a phase voltage, and at present for making the three-phase electricity balance, newly-built building substantially all feeds three-phase electricity, and the phase voltage that each household uses is also different, and is therefore impracticable; 2.CN92219396.7 disclosed a kind of multi-user's watt metering instrument, except the shortcoming that only adopts a phase voltage was arranged, its sampling period was unreasonable, can not accurately sample to three times in the electrical network or higher hamonic wave, so measuring accuracy was difficult to reach requirement.

The purpose of this utility model just provides one and adopts multichannel to measure respectively, show respectively, concentrate observing and controlling to multi-user's power consumption, and measuring accuracy height, power consumption is few, volume is little concentrating type digital kilowatt-hour meter.

The purpose of this utility model is achieved in that a kind of concentrating type digital kilowatt-hour meter is made up of A/D change-over circuit, CPU microprocessor system, data memory, Automatic Reading Instrument of Water Meter and input/output interface circuit that power unit, the sample circuit that comprises voltage signal sensing circuit, current signal sensing circuit, voltage signal amplifying circuit and current signal amplifier circuit, band sampling keep, and it is characterized in that: described power unit comprises an open-phase protection and warning circuit; Comprise a range automatic switchover part in the described current signal amplifier circuit; Described data memory adopts non-volatile RAM memory; Described concentrating type digital kilowatt-hour meter also comprises: a frequency measurement circuit, this frequency measurement circuit are located between the input interface of voltage signal sensing circuit output terminal and CPU microprocessor system; One degree impulse output circuit is located at the output terminal of CPU microprocessor; Power supply open-phase protection and warning circuit are connected between three-phase power line and the power supply input transformer, form by three relay J a, Jb, Jc and an alarm lamp L, described three relay J a, Jb, Jc respectively with one mutually power supply connect, and respectively have a normally closed point parallel with one another, L is connected in series with alarm lamp; Described voltage signal sensor is three, measures the phase voltage on the three-phase power line respectively; Described current signal sensor is n, measures the electric current on each Be Controlled user electric wire respectively; Frequency measurement circuit is by IC ₄Constitute, export a square wave identical with the line voltage frequency; Described current signal amplifier circuit is the current signal amplifier circuit of changeable fluid, by IC ₂, IC ₃And and IC ₃The serial resistance that connects of output terminal form; Meter degree impulse output circuit is made of photoisolator, 3-8 code translator, driver and pulse counter; The voltage signal of back output is amplified in sampling and the signal of current signal and frequency measurement circuit output carries out data processing by the CPU microprocessor, meter-copy device is an infrared copying instrument, signal machine is as calculated handled the back and is divided the family to show by pulse counter, carries out automatically the metering of checking meter of branch family by infrared copying instrument simultaneously.

Concentrating type digital kilowatt-hour meter according to structure of the present utility model is made owing to adopt three-phase voltage to measure, makes the interior user power utilization of Be Controlled scope reach three-phase equilibrium; The frequency self-adaption system that adopts frequency measurement circuit and CPU to form, can when fluctuating, mains frequency still can keep the precision used, when sampling, adopt the sample mode of 3 subharmonic of can sampling simultaneously, to realize very high precision and sensitivity, its precision can reach 1 grade even higher, and starting current also can reach 0.002Ib; Can measure the power consumption of any number of users in the Be Controlled scope, machine is handled the back by the demonstration of meter degree impulse output circuit as calculated, utilizes infrared copying instrument to realize automatic data logging again.This table also has extended function simultaneously, functions such as additional multiple rate meter degree, current limliting are limited the quantity of, pre-payment power supply.As networking with central computer, can carry out real-time management to a regional power load, for power supply management department provides the automatic data logging metering, accurately analyzes and searching circuit line loss reason, accurately grasp the function of power load and increase-volume demand.

Concrete structure of the present utility model is further provided by following embodiment and accompanying drawing thereof.

Accompanying drawing 1 is the schematic block circuit diagram of the utility model embodiment,

Accompanying drawing 2 is frequency measurement circuit schematic diagrams of the foregoing description;

Accompanying drawing 3 is voltage signal amplifying circuit schematic diagrams of the foregoing description;

Accompanying drawing 4 is changeable fluid signal amplification circuit schematic diagrams of the foregoing description;

Accompanying drawing 5 is power supply open-phase protection and warning circuit schematic diagrams of the foregoing description.

See also figure one: the utility model embodiment comprises: sample circuit 1, the A/D change-over circuit 21,22 that the band sampling keeps, frequency measurement circuit 3, CPU microprocessing systems 4, data memory 5, meter degree impulse output circuit 6, Automatic Reading Instrument of Water Meter 7.Sample circuit 1 comprises voltage sensor 11, current sensor 12, multiway analog switch 13,14, voltage amplifier circuit 15 and current amplification circuit 16.Voltage sensor 11 is made up of three voltage transformer (VT) Va, Vb and Vc, and the phase inductance with three-phase electricity converts low-voltage signal to respectively; Current sensor 12 is made of n current transformer array, is used for the current conversion on each subscribers feeder is become low voltage signal.The low-voltage signal of output is added to multi-channel analog switch circuit 13 and 14 respectively, and multi-way switch circuit 13 is used for the gating voltage signal corresponding with selected current signal, is controlled by CPU microprocessor output signal; Multi-way switch 14 is used for gating multi-user's current signal, is also controlled by CPU microprocessor output signal.Be added to frequency measurement circuit 3 and voltage signal amplifying circuit 15 simultaneously from the signal of multi-way switch circuit 13 outputs, the output signal of frequency measurement circuit 3 directly is added to the input interface of CPU; The output signal of voltage signal amplifying circuit 15 is added to the A/D change-over circuit 21 that the band sampling keeps, and is input to the input interface of CPU then.

The concrete electrical schematic diagram of frequency measurement circuit 3 is asked for an interview Fig. 2, by comparator circuit IC ₄Constitute IC in the present embodiment ₄Adopt LM311 model integrated circuit, it exports a square wave identical with the line voltage frequency, detect the width of its positive pulse by CPU and calculate the line voltage frequency, frequency measurement circuit 12 and CPU component frequency adaptive system, therefore, this watt-hour meter can still can keep stabilized accuracy when the line voltage frequency jitter.

The electrical schematic diagram of voltage signal amplifying circuit 15 is asked for an interview Fig. 3, and its physical circuit is by operational amplifier IC ₁Constitute, present embodiment adopts LF356 model integrated circuit, and it gains by resistance R ₁And R ₂Adjust, concrete formula is: $V_o=(1+\frac{R_1}{R_2})V_{\mathrm{io}}$ The circuit diagram of current signal amplifier circuit 16 is asked for an interview Fig. 4, and physical circuit is by amplifier IC ₂With multi-way switch IC ₃Constitute present embodiment IC ₂Adopt the LF356 integrated circuit, IC ₃Adopt the LF135 multi-way switch circuit, IC ₃Many input ends connect a range transfer resistance R respectively _1-8, therefore the utility model has the range function of conversion automatically because current signal amplifier circuit has adopted above structure, and the electric current amplifying signal is input to the CPU microcomputer by A/D change-over circuit 22, and CPU can be according to the size control multi-way switch IC of input signal ₃The circuit that gating is different can obtain different gains, realizes the automatic adjusting to range, even make this watt-hour meter for than small-signal, also can obtain satisfied precision, and concrete formula is: $I_o=(1+\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{R}_i}{\underset{j=n+1}{\overset{8-n}{\mathrm{\Σ}}}{R}_j})I_i(I\≤n\≤7)$

As CPU gating S _oDuring the road, enlargement factor is 1.

A/D converter 21 and 22 adopts 12 successive approximations of band sampling holders, and it is controlled by CPU, is converted into digital signal again at certain moment sampled voltage or current signal and send CPU to handle.CPU can calculate user's power consumption behind the voltage in the same moment that receives A/D conversion, current instantaneous value.

CPU4 deposits it in data memory 5 in after calculating each user's power consumption, the data memory 5 of the utility model embodiment adopts nonvolatile RAM memory, it has the characteristics of RAM quick data transfering, possesses the advantage of EEPROM long preservation data again, need not to be equipped with to use battery.In addition, accurate in order to guarantee the data in the data memory, CPU can regularly manage and safeguard the data in the memory, guarantee that it is accurate.Behind each user's that it records the power consumption, after handling, CPU shows by meter degree pulse display circuit, this meter degree pulse display circuit 6 is made of photoisolator 61,3-8 code translator, 62 drivers 63, pulse counter 64, pulse counter 64 shows each user's power consumption, can utilize infrared copying instrument 7 to realize automatic data logging.

The utility model watt-hour meter has increased open-phase protection and warning circuit 8 when designing power supply, ask for an interview Fig. 5, and physical circuit is by three relay J _a, J _b, J _cConstitute, these three relays are respectively the relay of three-phase electricity A, B, C control voltage.When A has electricity mutually, by relay J _aB, C phase are cut off in control, and power supply is powered mutually by A; When A has a power failure mutually, relay J _aControl is connected the B phase and is cut off the A phase; If B also has a power failure mutually, relay J _a, J _bControlled turn-on C phase again, to have electricity to guarantee mutually be the power supply power supply as long as promptly have one.Relay J _a, J _b, J _cRespectively have a normally closed point to be in parallel, its point in parallel is connected in series with alarm lamp L, as long as open-phase fault occurs, alarm lamp promptly can luminously be reported to the police.

The utility model watt-hour meter also has extended function, can add multiple rate meter degree easily, current limliting is limited the quantity of, functions such as pre-payment power supply, if one regional power load is carried out real-time management with central computer, also can be power supply department the automatic data logging metering is provided, accurately analyze and searching circuit line loss reason, accurately grasp the situation of power load and increase-volume demand.

Claims (6)

1. concentrating type digital kilowatt-hour meter, by power unit, the sample circuit that comprises voltage signal sensor, current signal sensor, voltage signal amplifying circuit, current signal amplifier circuit, the A/D change-over circuit that the band sampling keeps, the CPU microprocessor system, data memory, Automatic Reading Instrument of Water Meter and each input/output interface circuit are formed, and it is characterized in that:

Described power unit comprises an open-phase protection and warning circuit;

Comprise a range automatic switchover part in the described current signal amplifier circuit;

Described data memory adopts nonvolatile RAM memory;

Described concentrating type digital kilowatt-hour meter also comprises:

One frequency measurement circuit, described frequency measurement circuit are located between the input interface of the output terminal of voltage signal amplifying circuit and CPU microprocessor;

One degree impulse output circuit is located at the output terminal of CPU microprocessor.

2. concentrating type digital kilowatt-hour meter according to claim 1 is characterized in that: described power supply open-phase protection and warning circuit are connected between three-phase power line and the power supply input transformer, by three relay J _a, J _b, J _cForm described three relay J with an alarm lamp L _a, J _b, J _cRespectively with one mutually power supply connect, and respectively have a normally closed point parallel with one another, L is connected in series with alarm lamp.

3. concentrating type digital kilowatt-hour meter according to claim 1 is characterized in that: described voltage signal sensor is made of three voltage transformer (VT), measures the phase voltage on the three-phase wire respectively; Described current signal sensor is made of the current transformer array, measure respectively the multi-user with the electric current on the electric wire.

4. concentrating type digital kilowatt-hour meter according to claim 1 is characterized in that: described frequency measurement circuit is by IC ₄Constitute, export a square wave identical with the line voltage frequency.

5. concentrating type digital kilowatt-hour meter according to claim 1 is characterized in that: the range in the described current signal amplifier circuit automaticallyes switch part by IC ₃And the resistance that input end connects constitutes.

6. concentrating type digital kilowatt-hour meter according to claim 1 is characterized in that: meter degree impulse output circuit is made of photoisolator 3-8, code translator, driver, pulse counter.

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