WO2012011827A1

WO2012011827A1 - Electricity meter

Info

Publication number: WO2012011827A1
Application number: PCT/PH2010/000009
Authority: WO
Inventors: Jovita K. Yeo
Original assignee: Yeo Jovita K
Priority date: 2010-07-22
Filing date: 2010-08-23
Publication date: 2012-01-26

Abstract

An anti - tampering electronic kilowatt -hour meter being powered by line voltage with predetermined threshold operating range and operating frequency comprising: sensing means, an analog-to-digital conversion circuit in communication with said sensing means being operable of converting voltage and current pulse signals from the sensing means into sampled pulse data stream information, a microcontroller unit for processing said sampled pulse data stream information and generate power consumption information and pilferage indicative information, which in turn is displayed by a data display means, the pilferage being detected upon detection of reduced, interrupted or unbalanced pulse signal input coming from said analog-to-digital conversion circuit.

Description

ELECTRICITY METER

Technical Field:

The present invention relates generally to electronic meter and more specifically to an anti-tampering electronic kilowatt-hour meter.

BACKGROUND OF THE INVENTION

Electrical utility meters, or watt-hour meter, measure electrical energy consumed by a facility. Electrical utility service providers, or simply utilities utilizes watt-hour meters to collect data on energy consumption for customer billing and other purpose. The most common type of electric meter is the electro-mechanical indiction watt-hour meter which operates by counting the number of revolutions of an aluminum disc provided thereof. The disc rotates at a speed proportional to the power such that the number of revolutions is, thus, proportional to the energy usage. This meter has been used for quite a long time and has been proven to be effective in its intended purpose. However, this meter utilizes numerous mechanical parts and its production is quite costly.

To remedy the aforesaid problems, electronic meters were introduced ,wherein the structure is quite simpler and yet has several functions that would provide data required in assessing different billing requirements. Electronic meters can measure the electric energy consumption by sampling scaled-down versions of the voltage and current waveforms on the power lines of a facility and then performing consumption calculation using the sampled waveforms. The electric energy consumption is then displayed in a liquid crystal display (LCD). It can also record other parameters of the load and supply such as maximum demand, power factor and reactive power used. It can also support time-of-day billing, for example, recording the amount of energy used during on-peak and off-peak hours. An electronic meter has a power supply, a metering engine, a processing and communication engine, such as microcontroller unit and other add-ons modules, such as real time clock, (RTC), LCD display and communication ports/modules. The meterting engine provides the voltage and current inputs with a voltage reference, samplers and qualifiers followed by an analog-to- digital converter (ADC) section to yield the digitized equivalents of all the inputs. These inputs are then processed by the microcontroller unit to calculate the various metering parameters such as power, energy, etc. The processing and communication section has the responsibility of calculating the derived quantities from the digital values generated by the metering engine. This also is responsible in communicating using various protocols and interface with other add-on modules connected as slaves to it. Real time clock (RTC) and other add-on modules are attached as slaves in the microcomputer unit for various input/output function, all of this are being implemented in the microprocessor.

An example of an electronic meter is disclosed in U.S. Pat. No: 4,692,879, wherein the meter includes a power measuring device and a clock circuit, a data setting device for setting data such as time zones, holidays and the like and programs is detachably connected to a data transmitting circuit.The memory circuit is further provided with Programmable Read Only Memory Device (PROM) for storing the set data and programs and a Read Only Memory Device (ROM) for storing programs required for receiving the set data and programs through the data transmission circuit and storing the same in the PRTOM. Under the control of a CPU, an electric power measured by the power measuring device is processed in accordance with the data and programs stored in the PROM and displayed on a displaying device, while the data setting device itself is removed from the watt-hour meter after the data and programs have been memorized in the PROM.

In the above-described electronic watt/hour meters, the is no functionality is included with regards to detection of pilferage of power. Meters of the aforesaid types can be easily manipulated to make them under-register, effectively allowing power use without paying for it. Power companies or service providers just rely on on-site physical inspection of the meter terminals to detect power theft or pilferage. Some kind of of pilferages include "reverse polarity with the grounding", which is common in urban multi-dwelling area, the so called " open potential", wherein pilferage is done by regulating the kw/hour meter potential in accordance with the consumer desire. Another is the use of reversing transformer wherein the pilferer reversed the connection and plugging the reverse transformer on the convenience outlet causing the ordinary analog meter to reverse, and the "single line connection grounding", wherein on line or neutral conductor is being used as control mechanism in registering the kilowatt hour, and the commonly used shunting of any or both terminals with a conductive material. Substantial amount in terms of profit is lost due to this unlawful practice and physical inspection to minimize such pilferage is, however, rather tedious and time-consuming. SUMMARY

In view thereof, it is the primary object of the present invention which can remedy the above drawbacks of the prior art.

Another object is to provide an electronic meter which can deter meter tampering having specific function program within the microcontroller unit of the meter being made such that it is capable of determining power pilferages in case the meter is tampered.

Still another object is to provide an electronic meter having concrete non-reversible and visible means of identifying meter tampering, without power interruption on the part of the end user on a 3 -wire metering system.

Yet another object is to provide an electronic meter wherein LCD display is continuous even at de-energized state with a supplied internal power integral to the meter as a convenience both to the utility or service provider and end user.

Another object of the present invention is to provide an electronic meter which can deter if not eradicate non-technical energy loss due to pilferage caused by shunting of any or both meter terminals with a conductive material.

Other objects and advantages of the present invention wil be realized upon reading the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 is a block diagram of the electronic meter of the present invention,

Figure 2 is an illustrative presentation of pilferage in an electronic meter; and

Figure 3 is another illustrative presentation of another way of pilferage in an electronic meter.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1 of the drawings, there is illustrated an electronic kilowatt-hour meter generally designated 10 being powered by line voltage with predetermined threshold operating range and operating frequency. Meter 10 comprising sensing means 11, an analog- to-digital conversion circuit 12 in communication with sensing means 11, and a microcontroller unit 14 in communication with said pair of analog-to-digital conversion circuit 12 .

Sensing means 11 consisting of a voltage and current sensors 11a and lib, both being connected to the power lines L. Voltage sensor 11a being capable of generating voltage pulse signal representing scaled voltage waveform on the power lines, and current sensor lib being made such that it is capable of generating current pulse signals representative of the scaled current waveform on the power lines L. Analog-to-digital conversion circuit 12 comprises a voltage pulse signal converter 12a and current pulse signal converter 12b. Voltage pulse signal converter 12a being connected to the voltage sensor 11a and capable of converting voltage pulse signal from the voltage sensor into sampled voltage pulse data stream for processing in the microcontroller unit. Current pulse signal converter 12b being connected to the current sensor lib, and being made such that it is capable of converting current pulse signal from the current sensor into sampled current pulse data stream for processing in the microcontroller unit. These digital pulse signal is then transmitted to the microcontroller unit 14. The microcontroller unit 14 (MCU) is operable for constantly monitoring the input digital pulse signal generated by the analog-to-digital converters (ADC). It stores the encrypted C language executable program responsible for calculating the power consumption, logic control , clock and data manipulation. The microcontroller unit includes a power processing circuit 15 being made such that it is capable of calculating the power consumption. It is capable of receiving the voltage and current pulse signals from the analog-to-digital converters, which in turn are processed to obtain power consumption data in watt-hour. Said power processing circuit 15 being in communication with a data display means, such as a liquid crystal display (LCD) 16, wherein the calculated power consumption data is transmitted and displayed. A pilferage detecting circuit 17 is further provided in the microcontroller unit 14 being made such that it sub-routine program is capable of detecting reduced, interrupted or unbalanced pulse input in the analog-to-digital conversion circuit. Said pilferage detecting circuit 17 being in communication with the liquid crystal display (LCD) such that the abnormality or indication of pilferage is subsequently transmitted and indicated in the liquid crystal display. Said microcontroller unit 14 further includes a non- volatile random access memory circuit 18 being operable of storing the metered data and metering parameters which does not require power supply to retain information. A back-up power supply means, such as rechargeable battery 17, is in communication with the microcontroller unit being made such that it is capable of supplying power to the microcontroller unit to prevent the loss of display in case of power failure.

The following are different sequences for pilferage indication of the present invention. When a load is connected to the line voltage source LI and L2, current flows in a closed circuit. The voltage and current sensors 11a and lib recognize the unidirectional flow of current circulating around the circuit closed path, both current sensors complement each other as input to the analog-to-digital converters (ADC). When a by-pass conductor is placed on either or both lines and the load, the flow of current in the current and voltage sensors is reduced, interrupted or become unbalanced. As this happens,the converters triggers an independent impulse output which is transmitted to the microcontroller unit. A reduced, interrupted or unbalanced pulse input generated by the analog-to-digital converters (ADC) activates the command prompt of the pilferage detecting circuit and transmit the unbalanced pulse input to the liquid crystal display (LCD) wherein the abnormality is indicated and displayed . The sub routine program of the pilferage detecting circuit is set to permanently display the indication even when the distorted signal from the ADC due to abnormality in the sensing device is removed.

In case a by-pass conductor is placed on either or both the metering terminals as shown in Figures 2 and 3, the current I in the closed circuit will not be the equal translation of the current output of the current sensors, thus, the output current of the analog-to-digital converter (ADC) is reduced or unbalanced (distorted). The pilferage detecting circuit of the microcontroller unit (MCU) responsible for monitoring this input is triggered and its subroutine program activates the LCD to display the pilferage indication.

Claims

1) An anti-tampering electronic kilowatt-hour meter being powered by line voltage with predetermined threshold operating range and operating frequency comprising:

sensing means being made such that it is capable of generating current and voltage pulse signals representing scaled voltage and current waveform on the power lines, an analog-to-digital conversion circuit in communication with said sensing means being operable of converting voltage and current pulse signals from the sensing means into sampled pulse data stream information, a microcontroller unit in communication with said analog-to-digital conversion circuit operable for processing said sampled pulse data stream information and generate power consumption information and pilferage indicative information, which in turn is displayed by a data display means, said microcontroller unit includes a power processing circuit and a pilferage detecting circuit being executable by sub-programs for calculating power consumption and pilferage detection, said power processing circuit being capable of calculating power consumption based on the received voltage and current pulse signals from the analog-to-digital conversion circuit, and said pilferage detecting circuit being operable upon detection of reduced, interrupted or unbalanced pulse signal input coming from said analog-to- digital conversion circuit, said microcontroller unit further having a nonvolatile random access memory circuit being made such that it is capable of storing metered data and metering parameters which does not require power supply to retain information, and a back-up power supply means in communication with said microcontroller unit for supplying power thereof in case of power failure.

2) An anti-tampering electronic kilowatt-hour meter according to claim 1 wherein said data display means is a liquid crystal display.

3) An anti-tampering electronic kilowatt-hour meter according to claim 1 wherein said microcontroller unit being operable by encrypted C language executable program.