The present invention refers to the centralized measurement, registering reading and billing of electric en- ergy consumption and, more specificaly, to a method and equip¬ ment to be installed preferably near residential blocks of apartments, commercial and industrial buildings and intended to measure, register and provide information regarding indi¬ vidual and global electric energy consumption, according to simple or complex tariffs, allowing manual, automatic and/or remote centralized reading of the consumption data, with an option being provided for the local emission of bills and/or pre-payment, and also permiting the switching of electric charges in accordance to predetermined programs and/or remote control signals.

Historicaly, low voltage electric energy distribu¬ tors bill their clients for the consumed electricity according to consumption readings obtained from individual meters. These meters, installed near the consumers, are conventionally read in loco, and the readings thus obtained are send to the dis¬ tributing companies for processing and billing of the clients. This method and the related equipments have been im¬ proved and modified in an atempt to obviate several associated problems and shortcomings which, in a situation of large aglomeration of consumers, such as in large apartment buildings, are even more serious.

A first aspect to be analysed, with regard to those problems and shortcomings, is the electric energy meter it¬ self, which is utilized for the purposes of billing the con-

sumers .

Electricity billing has been mostly carried out with the utilization of electromechanical meters, derived from a technology 100 years old. In spite of their large scale use, this type of meter presents several problems, the most impor¬ tant being:

Lack of flexibility for the addition of new func¬ tions. The evolution of the billings procedures has resulted in the possibility and necessity of measuring and registering new types of values, such as maximum energy demand and differ¬ entiated consumption according to the period of the day (hour based tariffs). Since the electromechanical meters are, in fact, mechanical clock mechanisms in their original concepts, they are not compatible with modifications and/or addition of new functions, and their physical design must be altered when¬ ever a new requisite is necessary; and

Lack of precision in the consumption measurement, which become excessive with time and under certain electric charge conditions. As their operation is based in the contin- uous movement of internal mechanical parts, the electromechanical meters present a cumulative wear with time, heavily affecting their nominal precision characteristics, even being subject to failure in registering small electric charges, with the consequent prejudice to the distributing company. Moreover, this type of meter only measures, in an ad¬ equate manner, the first harmonic of the line frequency (usu¬ ally 60Hz). The increasing introduction of other frequency harmonics into the electric energy distribution systems, mainly caused by switched and intermittent charges, causes the electromechanical meter ceasing to be reliable as a measuring device.

Another aspect refers to the usually employed method of reading the consumption. This method, which involves manu¬ ally registering the consumption data by employees of the dis- tributing company, who have to walk long distances to collect data from each meter belonging to a given distributing net¬ work, which network sometimes can have as much as several thousands meters, can be complicated, time consuming and sub¬ ject to failures and errors. It is quite common, indeed, that

the person in charge of checking the meter can not gain access thereto due to closed gates, absense of people in the house, or by any other reason. In these cases, the distributing com¬ panies have to estimate the consumption, based in the average prior measurements of that consumer, sometimes causing dis¬ tortions in the values to be billed, with the possibility of prejudice either to the distributor or to the consumer.

Moreover, since the reading is carried out visually through the glass cover of the meters, with the notes being taken manually by the person in charge, it is subjected to er¬ ror, such as those resulting from dirt meters installed in badly lighted locations or in improper positions making it im¬ possible the correct reading of the consumption indication. Finally, the stress to which the distributors employee is sub- jected, due to the reading of hundreds of meters per day and the writing of thousands of numbers per day, is another compo¬ nents which generates reading errors.

Having described in a generic sumarized manner the meter and the method of reading the energy consumption usually employed in the billing of low voltage electric energy, and the main problems and shortcomings associated thereto, it will be described hereinafter the several attempts to obviate the prior art problems so as to demonstrate the high inovative de¬ gree and improvements introduced by the present invention in relation to the said prior art.

Referring now to the meter itself, the main attempts to improve it refer to the use of electronic devices and cir¬ cuits capable of implementing several functions, so as to en¬ hance the flexibility of the electromechanical meter or even to completly substitut it.

In the first case, the electromechanical meters are provided with internal electronic devices and circuits. These circuits and devices are generally made of electronic plates containg integrate circuits (microprocessors, memories, etc), electronic displays and other peripheral elements.

Since the available space within the electromechanical meter is extremely limited not having been forseen in its original mechanical concept the adaptation of elements additional to its original design, the reliability of

- A -

the thus formed assembly is less than desired.

Another factor which makes it difficult the use of this solution in the low voltage electric energy billing is its high cost. The meter assembling plus its electronic de- vices easily reaches higher prices than the single meter, shifting its field of application to those where the measure¬ ment is more complex, which is contraty to what happens generaly in the low voltage measurements.

Those prior art meters are therefore hybrid sol- utions, where the portion referring to the measurement itself is carryed out by the electromechanical principle, subjected to a great amount of errors with time and upon certain condi¬ tions of electric charges, as previously commented.

The second case refers to the attempts of the prior art for a complete substitution of the electromechanical me¬ ters for an equivalent totaly based on electronic circuits and devices: the electronic meter.

This substitution alternative should theoreticaly eliminate the problems presented by the hybrid solution (electromechanical plus electronic devices), since measure¬ ments, now based on electronic principles, can be more precise and not subjected to disturbing effects on the electric charge side.

It has been partially verified in practice that, when an increasing substitution of the electromechanical meas¬ urements for the electronic, mainly in those ranges of elec¬ tric energy billing corresponding to high and medium voltages, where high energy consumers are located, such as steel proc¬ essing industries and other heavy industrial plants. The electronic meters in those ranges of billing generally offer great flexibility as to changes and/or addi¬ tion of function and a fairly superior precision in the con¬ sumption measurements, when compared to the conventional electromechanical meter. The comparative high cost of these meters is largely overcome by these advantadges and is irrel¬ evant when compared to the values related to the billing of great amounts of energy.

However, in low voltage billing, which is the area of major interest for the present invention, the cost of the

electronic meter has proved to be a major bar to its use, even with the progress occured in the modern electronic technology. The main reason for this situation is that the elec¬ tronic meter, when it offers only the consumption measurement function, or just a few additional functions, has not succeded in accompaining the lower price of the electromechanical me¬ ter.

This difference in prices is of utmost importance when it re¬ fers to a market of millions of pieces, as it is the case with the low voltage billing.

In this case, the requirements for improved preci¬ sion and higher flexibility are not met due to the higher price and the necessity of just a few functions.

The higher price of the electronic meter when com- pared to the electromechanical results to a great extent from the elements and auxiliary circuits used in the manufacturing of the meter, such as:

- power sources for the electronic circuits;

- protection elements against disturbs in the elec- trical network or in the charge (lightnings, short circuits, etc);

- voltage and current sensing elements for conform¬ ing the levels of those values to the processing capacity of the electronic circuits; and - electromagnetic shieldings for preventing the di¬ rect irradiation of strong fields of radio frequency.

The next step consists of analysing conceptually the prior art attempts with regard to the improvements in the method of consumption reading and billing. The attempts of improvement carried out until now make use of one or more of the three concepts which follow.

The first concept is that of the automation of the reading and billing method. The object in this case is to re¬ duce to a minimum human participation, so as to avoid errors and failures such as, for example, in the visual reading of the meters displays, in the manual registring of the consump¬ tion and others as above commented.

The second concept refers to the concentration of consumption data, so that the reading and/or transmission

thereof to the distributing company offices is carried out in the more efficient manner possible. By concentrating the con¬ sumption information of several meters in a single point, the reading can be accelerated and the accessing of groups of me- ters can be made instead of one by one.

The third and last concept refers to the remote com¬ munication. The concern in this case is to eliminate the intermediate steps in the reading method. The remote access, directly from the distributor offices to the consumer meters would be an example of the applicaiton of this concept.

A brief description will now be made together with the analysis of examples of the main reading and billing sys¬ tems proposed by the prior art.

The first example refers to the use of portable com- puters with reduced weight and dimensions for substituting the spreadsheet normally used by the distributors employee for registering the consumption data, the use of these devices, while facilitating and improving the quality of the employees work, by offering additional information for his use or even automaticaly carrying out the meter reading, does not elimi¬ nate the problems inherent to the access and slowness previ¬ ously cited, because the human element is still predominant in this method.

The second example refers to those systems in which the meter consumption information is automatically accessed and transmited to one or more concentrating devices for, finally, being sent to the distributor offices.

The communications means used in those systems can be of many types, including radio waves, energy distribution network wires or even dedicated wires, these systems, which try to combine the three previously cited concepts (auto¬ mation, concentration, remote communication) have in common a basic design element: The individualized measurement. in other words, all of them are based on individual meters (one unit per consumer), either of electromechanical or electronic technology. in these meters devices and circuits are added, so as to allow automatic or remote communication, signif¬ icantly increasing the cost of the measurement.

The third and last example, which refers basically

to the billing instead of reading, is directed to the systems where the consumer automatically buys certain amount of en¬ ergy, using for example coins, cards or numeric passwords. By using appropriate interfaces in the meter (a coin counter, a card reader or a numeric keyboard), the consumer makes a credit corresponding directly to the meter. The consumed and the remaining energy are shown in a display to the consumer, for its control in the acquisition of additional credits. This type of system, due to the inclusion of displays, inter- faces for the reception of the meter energy credit (coin counter, card reader or numeric keyboard), increases several times the total price of the measuring operation. In view of this, it is only used in special cases for consumers of great amounts of energy, where the high implantation costs are jus- tified.

In summary, the increase in the costs of the meas¬ urements have been frustrating a prior art attempts in provid¬ ing improved reading and billing systems, without increasing too much the final price. The main reason for that results from the fact that those systems are based on individual me¬ ters, where any added device represents an irreversible in¬ crease in the price.

Having analyzed the measurement and reading/billing systems of the prior art, attention will now be given to the more serious aspect found in those cases of aglomeration of consumers such as, for example, apartment buildings. This as¬ pect refers to the physical space occupied by the measurement facilities. In the case of the prior art, which can use se¬ veral hundreds of units in large building, this implies in the allocation of large areas generaly in the ground level of the building. Those areas for the installation for the meters some times are located in noble areas of the building such as lobbies or within specially built rooms. Any one of these cases mean a waste or bad utilization of the available area of the building.

Once characterized the main aspects of the prior art, the object and summary of the invention will now be de¬ scribed: a) to provide a centralized electric energy consump-

tion measurement, near high consumer concentrations, such as apartment buildings, which allows centralized reading and billing manually and/or automaticaly, with local and/or remote access, without the problems and shortcomings of the prior art. The use of a centralized measurement instead of individ¬ ual meters common to the state of the art, allows the improve¬ ment of the consumption measurement itself, the electric energy reading and billing, without undue increase of the costs, since the devices which are added to the measurement process have their costs shared with the several elements of the centralized system; b) to provide a centralized measurement of electric energy, where the individual meter used by the prior art are substituted for energy transducer modules. These modules, designated as ETMs, having physical dimensions smaller than those of the prior art meters, can be grouped in a large num¬ ber within a same box, designated as measurement unit (MU); c) to provide a centralized electric energy consump¬ tion measurement, wherein the ETMs share the common parts of the MU, such as the power supplies for the electronic cir¬ cuits, electric network protection elements, voltage sensors, registering, control and communication circuits contained at the MU; d) to provide a centralized electric energy consump- tion measurement, wherein the MU also contains an ETM designed to measure the highest electric charges, designated as "ser¬ vice ETM". The "service ETM" is responsible, in the case of apartment buildings, for measuring the energy consumption of electric pumps, central air conditioning systems, elevators and illumination of the common parts of the building, while the consumption measurement of the apartments is carried out by the normal ETMs; e) to provide a centralized electric energy consump¬ tion measurement, which, besides the normal and service ETMs, has a "global ETM", responsible for the measurement of the total electric energy supplied to all the consumers related to a given MU. The "global ETM" allows comparison of the sum of the measurements made by the individual ETMs, including the service ETM, and the total measurement, so as to facilitate

the detection of frauds, ilicit energy deviations and possible defects of the centralized measurement system; f) to provide a centralized electric energy consump¬ tion measurement, wherein the consumption information, pro- vided by the normal, service and global ETMs, are collected and registered in a non volatile manner, by a register/concentrator module (RCM), also located inside the MU. Besides the collection and registering, the RCM is also responsible for the communication of the MU with outside lo- cated means; g) to provide a centralized electric energy consump¬ tion measurement, wherein the consumption data from one or more MUs can be accessed from a single central point. Amongst the various possibilities, one can cite a system where the measurement can be locally carried out, by means of an ex¬ ternal reading unit (RU), provided with display means for vis¬ ual access to the registered consumption data and a device for connection with portable readers, thus also allowing the auto¬ matic reading of the consumption data. Another possible system would be, among others, the direct transmission of the data from the MUs to the distributor offices, utilizing appropriate interfaces at the RCM, for its dissemination through radio waves, wires of the electric energy distribution network it¬ self or even by the telephone lines. However, one must have in mind that this external reading unit (RU) is not part of the present invention, whereby it will not be described here im more detail; h) to provide a centralized electric energy consump¬ tion measurement, with the RCM being provided with processing capacity, for example by using a microprocessor, which would allow the implementation of multiple energy tariffs, such as an hour based tariff ("seasoned tariffs"). In this case, the RCM provided with a clock having an internal calendar or an interface for reception of remote command signals, can carry out the energy registration in a differentiated manner, sepa¬ rating the consumption in terms of hours, days or months. In this manner, these functions can be implemented in a single point, more accessible to the person in charge of reading the information. Besides, there is no necessity of alterations at

the MUs, due to the functional evollutions of the reading and/or billing system, such as changes in the tariff. Such functions could be alternatively executed by the RCM itself. These two systems also make possible the switching of electric charges for purpose of energy conservation and/or improvements in the quality of the services provided for by the distributor company. In this case, some charges, such as a central air conditioning system, electric pumps and heaters can be re¬ motely controlled, contributing therefore with the reduction of consumption peaks in the electric energy distribution net¬ work; and i) to provide a centralized electric energy consump¬ tion measurement, which allows its installation in already existant buildings, without the necessity of additional civil construction. The MU can be dimensioned so as to be installed at the same physical space occupied by the convencional dis¬ tribution boxes, usually employed by the distributor company for connecting the consumer related wires to the supply bar, which is, in turn, directly connected to the public energy distribution network. In this manner, not only additional civil construction and changes in the existing electric system can be avoided, but the conventional meters can be discarded, thus gaining more space at the construction and turning it more difficult tampering and frauds attempts. In summary, the present invention allows the cen¬ tralized measurement of electric energy consumption from one or more centralized meassuring units (MU), one or more reading/billing units (RU) and the communication means between the MUs and RUs. The MU consists, in its basic version, of a box con¬ taining:

- energy tranducer modules (ETM), which substitute the convencional electric energy meters;

- energy transducer module for high charges ("ser- vice ETM");

- energy transducer module for total energy measure¬ ment referring to all the consumers associated to the MU ("global ETM") ; register/concentrator module (RCM) for collecting

and non volatile registering of the consumption information of all the ETMs of the MU, control of the functioning of the re¬ maining circuits of the MU, and communication of the MU with external means; and - power supply for the electronic circuits, voltage sensors, protection elements and communication circuits.

The RU is an unit external to the MU, and which function is to allow local pr remote eccess to the consumption information, as registered at the MUs to which it connects. The RU, considering the knowledge available from the state of the art, can be implemented so as to effect the visual presen¬ tation of the information, automatic and/or remote communi¬ cation with the distributor offices, local emission of bills and pre payment schedules. The communication means between MUs and RUs can be those of the prior art, such as data communication via radio short waves, dedicated lines and even wires from the distrib¬ uting network itself. Once the said communication means are widely known from the state of the art, and do not make part of the present invention, they will not be described in fur¬ ther details.

The system object of the present invention, due to its capabilities of convinient communication/control and lo¬ cation (near the energy distribuion branches for the consum- ers), allows the switching of electric charges according to predetermined programs and/or remote control signals.

The objects of the invention, its characteristics and advantages will be better understood with the description of its preferred embodiment, made with reference to the at- tached drawings, of which:

Figure 1 is a generic block diagram, showing repres¬ entations of the consumers associated to an installation pro¬ vided with the equipment for centralized measurement, registering, reading and billing, in accordance with the pre- ferred embodiment of the invention;

Figure 2 is a block diagram of an embodiment of the measuring unit (MU) shown in figure 1;

Figure 3 is a block diagram of an embodiment of the energy transducer module (ETM) shown in figure 1;

Figure 4 is a diagram representing an embodiment of the block of current sensors of figure 3;

Figure 5 is an electric diagram of an embodiment of the current sensor of figure 4; Figure 6 is a diagram representing an embodiment of the electronic energy transducer of figure 4;

Figure 7 is a drawing showing an internal view of the MU, with the ETMs, distribution bus bars and electrical connections for the consumers; Figure 8 schematically illustrates the bit string sent by the centralized measurement to the centralized reading/billing unit;

Figure 9 shows a preferred implementation of the interconnection of the several blocks which form the system object of the present invention;

Figure 10 is an schematic representation of a pre¬ ferred implementation of the centralized reading/billing unit; and

Figure 11 schematically illustrates a preferred em- bodiment of the register/concentrator module (RCM) according to the present invention.

The following elements can be schematically seen from figure 1:

- a concentration of consumers 13, which can be, for example, an apartment building; the distribution of electric energy for the con¬ centration of consumers 14, 15, 16, 17, through electric con¬ ductors 18, 19, 20, 21; the centralized measuring, registering, reading/billing equipment 10, and its main components: the centralized measuring unit MU-22, the centralized reading/billing unit RU-24 and the data communication means

23; the electric energy distribution network 11 and the inlet electric cable 12, which supplies energy to the said concentration of consumers 13 through the distribution carried out in the centralized measuring, registering, reading/billing equipment 10.

As it can be seen from this figure, the centralized

measuring unit MU 22, from now on simply designated as MU 22, can, conveniently, effect the distribution and measurement of energy delivered to the consumers 14, 15, 16, 17. These con¬ sumers can even include some which make use of the said high electric charges, such as those found in buildings and usually designated as "service" charges, and which may include water pump electric motors, central air conditioning systems, eleva¬ tors and illumination circuits for the common parts of the building. Once the energy is distributed, through MU 22, from the inlet electric cable 12 coming from the electric energy distribution network 11, it is possible to detect failures, tamper attempts, frauds or similar, by comparing the energy measurements received through the inlet cable 12 and that dis- tributed through the consumer connecting conductors 18, 19, 20, 21.

If a very large number of consumers is provided in the installation 13, and/or the formation of sub groups of consumers is considered necessary, several MUs 22 can be em- ployed. Accordingly, each MU 22 would be in charge of the cen¬ tralized distribution and measurement with regard to its associated sub group of consumers. The consumption information registered in each one of the MUs 22 could be periodically passed to one or more centralized reading/billing units RU 24. Preferably, the RUs would carry out a scanning of all the MUs to collect the information regarding the occurrence of energy pulses for each consumer.

It must be observed that each measuring unit (MU) contains only the information regarding the ocurrence or not of an energy pulsefor each consumer, within an scanning pe¬ riod. The accounting and accumulation of those energy pulses can be made by a programable electronic register (not shown), which must be installed within the RU.

This register, which may even be a conventional PER (programable electronic register), normally used in the meas¬ uring of high and medium voltage, with its software modified, must be capable of communicating with the MUs through a serial inlet, interpret the communication protocol, store all the in¬ formation regarding the.consumers and display the information

referring to each consumer.

Periodically, the microprocessor of this register selects, through the dedicated bus bars or through the network itself, one MU at each time. Having carried out the se- lection, the microprocessor of the selected MU responds to the RU microprocessor by sending a bit string, which contains the consumption information. This bit string is schematically shown in figure 8, where, if x = 1, then there is an energy pulse in the current scanning period; if x = 0, then such pulse does not exist. The Y bits are used for the detection and correction of communication errors.

All the responsability for the storing of informa¬ tion in case of energy failure is on this register.

This register must be provided with an optical con- nector for allowing communication with a radio transceptor and/or with a portable reader. The radio transceptor is ad¬ dressed via another transceptor, carried by a distributor em¬ ployee, which is in the vicinity of the building being considered. By means of a command emitted by the said e - ployee, all the information contained in the register are transmitted to his transceptor, which must be connected to a portable reader.

If the use of radio transceptors is not desired, the employee may connect its portable reader to the register op- tical connector, then carrying out locally and automatic read¬ ing of all the information referring to the consumers, or even manually taking notes of the values displayed at the register.

The data communication means 23 between one or more MUs 22 and the RU 24 can be chosen among the various devices available from the state of the art, such as those using radio transmission, conductors of the distribution network itself or via dedicated wires (coaxial cables), which can pass through the same ducts used for the energy distribution cables for the apartments. Since the equipments capable of implementing this data communication means 23 are already known from the state of the art, and is not a part of the present invention, it will not be described in further detail. In any case, some data communication means have been described at the "VI Inter-

national Conference on Electricity Supply Measuring and Bulling Apparatus", held from April 3 to 5 of 1990 in Manchester, United Kingdom.

The RU 24 allows suitable access from a single point, to the consumption information of one or more MUs 22, referring to the installation 13. Considering specific condi¬ tions of the installation 13 and of the prior art knowledge, several solutions and configurations for the transmission of consumption data until the distributor offices can be uti- lized, such as:

- the RU 24 may consist of a conveniently located unit at the installation 13, where visual readings regarding the consumption and other information related to the one or more MUs 22 of the installation 13, can be locally made through the display. Besides, the RU 24can effect reading of water and gas meters, from suitable adaptations made to these meters;

- the RU 24 can be provided, besides the display for visual reading, with an optical interface for connection with portable readers, thus allowing automation of the local read¬ ing; and

- if a remote consumption reading is of interest, it is possible to provide the RU 24 with means known from the state of the art, for the transmission of the consumption data, using, for example, radio waves, telephone linesor transmission through the conductors of the electric energy distribution network 11 itself. In the latter case, processes of transmission on an expanded spectrum of frequencies (gener¬ ally known as "spread spectrum"), can be used. A local concentrator can put together all the information of several MUs 24, referring to several installations 13, transmitting it in a suitable manneruntil the distributor offices, for exam¬ ple, by means of a telephonic modem. If considered convenient, the MUs 22 themselves can carry out this transmission function for remote reading, using the already exemplified means, and the RU 24 can be disregarded.

As already mentioned, the RU is not an essential part of the invention and, accordingly, its constructive de¬ tails will be omitted herein. In any case, several devices are

known from the state of the art, which are capable of imple¬ menting the functions of the RU, as above described. An exam¬ ple of this device would be the one described in the UK patent 2,046,924. If the necessity of utilizing one or more individual meters in the installation 13 persists, these could be pro¬ vided with suitable interfaces for connection to the central¬ ized measuring, registering, reading/billing equipment 10, either through the MU 22 or directly to the RU 24. In the examples of configurations of the equipment

10, in which the RU 24 is a remote element, or does not exist as a function of the data transmission capability of the MUs 22, it could still be necessary to have the possibility of visual and local reading of the consumption data at the in- stallation 13. One possible reason to this could be, for exam¬ ple, to provide a consumer with the right to have free access to the reading of the data pertainig to its consumption. In this case, it could be used an auxiliary reading unit or a display could be provided in the MUs 22, thus allowing the consumer locally to check the consumption associated to his apartment.

Figure 2 represents a basic scheme of the internal arrangement of a MU 22, according to a preferred implementa¬ tion of the invention, having the following elements: - the inlet electric cable 12, which supplies all the energy to the consumers associated to the MU 22;

- the electrical conductors 18, 19, 20, 21 for the consumer connection to the installation 13, as already ex¬ plained with reference to figure 1; - data communication means 23 between the MU 22 and the RU 24, and/or external means (in the case of a remote data transmission from the MU 22 itself); the energy transducer modules (ETM) 28, 29, 30, 31, responsible for the measurement of electric energy con- sumption. Each ETM is associated with one consumer of instal¬ lation 13;

- the ETM 30 for the high charges generally associ¬ ated to common electric circuits and building service instal¬ lations;

- the "global ETM" 25, referring to the measurement of all the electric energy entering the MU 22, which is to be distributed to the consumers associated thereto;

- the register/concentrator module (RCM) 26, respon- 5 sible for collecting and registering the consumption informa¬ tion supplied by the ETMs 25, 28, 29, 30, 31, for the controlling of the operation of the MU 22, for the data trans¬ mission to the RU 24 and/or external means, and for the visual presentation of the consumption information through a display,

10 if this is the case;

- power supply module and voltage sensors 27, con¬ taining the power supplies for the electric and electronic circuits of the MU 22 and the voltage sensors, which adequate the levels of electric voltage present in the conductors 18,

15 19, 20, 21, reducing them to levels compatible with electronic process for determining the energy at the ETMs 25, 28, 29, 30, 31;

- data, signals and supply bus bar 33, which pro¬ vides interconnection between the several elements of the MU

20 22, such as the ETMs 25, 28, 29, 30, 31, the RMC 26 and the power supply/voltage sensors module 27; and

- the electric energy distribution bus bar 32, where the energy delivered from the inlet cable 12 is distributed to the consumers served by the MU 22 through their individual

25 connections 18, 19, 20, 21.

The main energy inlet cable 12, alredy shown in fig¬ ure 1, supplies all the energy to be distributed to the con¬ sumers associated to a given MU 22. The use of the "global ETM" 25 at the inlet of the MU 22, allows the measurement of

30 all the energy in a natural and easy manner.

The energy is distributed to the consumers through connection of the electrical conductors 18, 19, 20, 21, made directly with the energy distribution bus bar 32, which is connected to the cable 12. This bus bar 32 consists, in the

35 preferred implementation of the invention, of bus bars verti¬ cally positioned inside the MU 22, wherein, through screw and terminal type connections, are connected the energy conductors which supply the consumer units 14, 15, 16, 17. This distrib¬ ution solution is coincident with the practice presently

adopted by electrical energy distributing companies and, therefore, benefits from already proved procedures.

The energy conductors 18, 19, 20, 21, which supply the consumer units 14, 15, 16, 17, upon connection to the bus bar 32, pass through current sensors 34 (shown in figure 3) of the ETMs 28, 29, 30, 31, causing the consumption measurement to happen in an automatic manner, that is to say, in order to make a connection of a consumer, an associated ETM 28, 29, 30, 31 is already provided. The "global ETM" 25 has its sensors 34 crossed by the cable 12, connected to one of the ends of the bus bar 32, thus allowing the the total energy measurement delivered to a MU 22. To the other end of the bus bar 32 are connected, via sensors 34 of the service ETM 30, the conductors referring to the highest electric charges, ususlly related to the services common in building installations, such as water pump motors, central air conditioners, elevators and illumination in gen¬ eral. Both the sensors 34 of the "global ETM" and those 30 of the service ETM have a dimensioning adequate to the high elec- trie currents present in cable 12 and conductors 20 for sup¬ plying energy to heavy charges.

The consumption information, provided by ETMs 25, 28, 29, 30, 31 is collected by RCM 26. This consumption infor¬ mation is transmited through the signal and supply bus bar 33, which interconnects the RMC 26, ETMs 25, 28, 29, 30, 31 and the power source/voltage sensors module 27. If individual consumptiom meters are provided outside the MU 22, the consumptiom information determined thereby are collectedthrough the external communication means 23 of MU 22, or by direct connection to the RU 24, as previously mentioned.

In the distribution of electric energy, in view of the field of application of the present inventin, the voltage, namely the level of electric tension, present in the supply conductors 18, 19, 20, 21 of the consumers 14, 15, 16, 17, of an installation 13, such as a apartment building, is deter¬ mined by the voltage at the electric cable 12. Since this voltageis common to the MU 22 consumers, a single group of voltage sensors. (not shown) is necessary for the determination of the voltage which is present in all the energy conductors

of these consumers. This information, which refers to the level of electric voltage at the cable 12 is generated by the voltage sensors of the power source/voltage sensors module 27, and transmited by the bus bar 33 to all ETMs 25, 28, 29, 30, 31 of MU 22. The information consists of electric voltage signals of reduced amplitude, proportional to the voltage at the cable 12, and appropriated to the processing by the elec¬ tronic circuits of the ETMs 25, 28, 29, 30, 31. The generation of these signals is made, according to a preferred embodiment of the invention, by voltage transformers using magnectic ma¬ terials, shieldings for protection against electric noises and insulation against high voltage disturbances present in the distribution network 11, in a precise and carefull manner, since its cost is shared by the number of ETMs 25, 28, 29, 30, 31 served thereby. In this manner, the invention provides lev¬ els of performance, protection and reliability higher than those of the prior art, without undue increase in the costs.

The above mentioned voltage sensors are known per se as, for example, from FR n° 2,522,156.The same can be said with regard to the power sources 27 of the electronic circuits of the modules contained in the MU 22. This supply, which is distributed to the ETMs 25, 28, 29, 30, 31 and RCM 26 through bus bar 33, is of common use in relation to the MU 22 elec¬ tronic circuits and, therefore, has its cost shared. In this manner, the power sources 27 can have high levels of perform¬ ance, protection and reliability, such as those which are found in prior art designs, which use redundance, electromagnetic shieldings and overdimensioning, without ex¬ cessive increase in the costs. A power source of this type is known from Brazilian Patent Application PI 8504693.

The RCM 26 has a microprocessor, a ROM (read only memory) containing the respective software and a RAM (random access memory) sufficient for storing the energy pulse occur¬ rences of all the ETMs. The main function of these devices is periodically to collect consumption information, obtained from the ETMs 25, 28, 29, 30, 31, its processing and non volatile registering, and the consumption data transmission through communication means 23, such as, for example, a single coaxial cable, via radio, or via the electric energy conductors them-

selves, as previously mentioned. This transmission can be car¬ ried out until the level of the local or remote RUs 24, in re¬ lation to the installation 13.

Practical examples of RCMs are those described in UK 2,149,128; EP 0 015 120 and US 4,516,213.

Since the RCM 26 is provided with a microprocessor, work memories, programs and non volatile data, it can execute in an extremely reliable and flexible manner the functions of collecting, registering, processing and transmitting the con- sumption data referring to the consumers 14, 15, 16, 17 of the installation 13. The RCM 26 can also be provided with elec¬ tronic clock circuits, facilitating the registering of instan¬ taneous occurrence of events at the MU 22, which are of interest for the electric energy distributing company. The use of interfaces for the bidirectional communi¬ cation between the RCM 26, through the communication means 23 of the MU 22, allows flexibility in the charge control schemes from, for example, contactors directly contrlled by the RCM 26, or even the implementation of tariffs where the consump- tion must differentiated according to the hour of the day, usually known as seasoned tariffs.

As an additional observation, it could be pointed out that the MU 22 can be provided with a device for communi¬ cation with portable automatic readers through, for example, electrical or optical connectors.

Besides, since the RCM 26 is provided with intelli¬ gence (a microprocessor), the several methods known to the state of the art can be implemented, with regard to attempts of violation of the MU 22, or unauthorized access or reprograming; and the implementation of a differentiated tar¬ iff does not require changes in the system of measurement, but only in the corresponding software, which will then count the pulses according to differentiated parameters.

Moreover, according to the preferred embodiment of the invention, the component blocks of the MU 22, such as the ETMs 25, 28, 29, 30, 31, RCM 26 and power source/voltage sen¬ sors 27, can be mounted according to the concept of "plug pro¬ vided modules", which can be pressure connected inside the MU 22, with the help of guide rails, thus facilitating the in-

stallation, servicing and field substitution (figure 7).

The above mentioned blocks can be made in the form of shielded units, without the possibility of disassembling for internal access, thus turning it difficult any tampering attempt. Another alternative would be making the said blocks in the form of units capable of being disassembled, for easier servicing, but provided with tamper indicating means, with a non volatile register at the RCM 26. Such options can be de¬ fined as a function of the distributing company interests or operation philosofy.

According to the preferred embodiment of the in¬ vention, the bus bar 33 for the interconnection of the blocks of the MU 22, is located within a shielded conduct inside the MU 22 box, thus preventing fraud attempts by interferences in the external signals which pass thereto (figure 7).

Figure 3 presents a simplified diagram, showing the internal arrangement of one of the ETMs, in this case the one indicated by reference number 28 in figure 2, according to the preferred embodiment of the invention, where the block of cur- rent sensors 34, the energy transducer circuit 35 and the con¬ necting element 36 between them, are illustrated.

Comparing the arrangement of the present invention ETMs 25, 28, 29, 30, 31, with those of the prior art meters, it is clearly seen that the centralized measurement in accord- ance with the invention allows the omission of several ele¬ ments, such as voltage sensors and associated protection devices, power sources and related protection devices, display means for the consumption related values, connecting terminals for the electric current conductors, a housing or box for ex- ternal installation, covers and fixing means thereto. Those elements are implemented in the common use blocks of the MU 22, which costs are shared by all the ETMs 25, 28, 29, 30, 31, as already explained. This great simplification allows the ETMs to be made with a more compact design and housed in sim- pie and strong boxes, having a cost lower than that of an electromechanical meter, and having the capability of being installed in a large number inside the MU 22, without exceed¬ ing the typical convencional dimensions of the boxes, which would also be substituted according to the invention. This

simplification means higly reduced costs, when compared to the measurement solutions offered by the prior art.

The installation of the ETMs 25, 28, 29, 30, 31 is additionally simplifified, since, being "pluggable units", they can be inserted as "drawers" into the guides existing in the box of the MU 22. When inserted, a male connector, inte¬ gral with each ETM fits into a corresponding female connector provided at the bottom of the space where the "drawer" is be¬ ing inserted into. The connection through these two connectors allows theat each module connects to the shielded signal, data and power supply bus bar 33 (figure 7).

Figure 4 shows the basic arrangement, according to the preferred embodiment of the invention, for the current sensors 34 employed in the ETMs 25, 28, 29, 30, 31. This con¬ figuration with three transformers 43, 44, 45 represents a polyphasic distribution arrangement. Other distribution can be attended with a variable number of transformers, according to the particular case (monophasic: 1; biphasic: 2), without prejudice to the scope of the invention. UK 2, 143,955 de¬ scribes a transformer of this type.

The current transformers 43, 44, 45 are, preferably, of the toroidal type, where the conductor 37, 39, 41, which carries the electric current to be transformed is the primary winding itself, passing through orifices 43', 44', 45', and making unnecessary additional connectors or connecting wires, for electrical connection with the electric charge which con¬ sumption is intended to be measured.

This type of sensor, thanks to its toroidal config- uration, presents a high performance and rgeat immunity to ex¬ ternal electric fields, and can be made of low cost and average performance magnetic materials.

The absence of additional connectors and wires re¬ duces the mounting costs, increasing its reliability and dura- bility uponovercurrents and overheating of the conductor 37, 39, 41, which acts as the primary winding , during abnormal conditions which can occur in the supplying of electric en¬ ergy.

The pairs of braided cables 38, 40, 42 represent the

outputs of the transformers 43, 44, 45, supplying currents of reduced amplitudes, but proportional to those found at the primary conductors 37, 39, 41. These currents, usually desig¬ nated as secondary currents, have amplitudes suitable to be processed by the electronic circuits of the energy transducer 35.

Figure 5 represents the invention preferred scheme for the implementation of the electrical protection of the current sensor 34 of the ETM 25, 28, 29, 30, 31. The toroidal current transformer 43, 44, 45, accord¬ ing to a preferred embodiment of the invention, consists of a transformer 46 with its primary winding formed by the conduc¬ tors 37, 39, 41 themselves, which carry the current of the consumer 14, 15, 16, 17, as already mentioned, and a secondary winding which, before connecting to the output wires 38, 40, 42, is protected by semiconductor diodes DI, D2. These two di¬ odes limit the maximum output voltage (38, 40, 42) of the transformer 46, protecting it against overcurrent failures at the primary side (37, 39, 41) and allowing its handling even during operation, in safe manner, with no rise of saturation of the magnetic material or damages to the insulation at the secondary side.

Figure 6 illustrates the basic elements which form the energy transducer 35 circuit. The signals used by the trasducer 35 are those which make part of the interconnection bus bar 33, such as, the supplying 48 for the electronic cir¬ cuit 47, the wires 49, 50, 51, 52, which carry the voltage proportional to the input of the conductors 18, 19, 20, 21, which feed the consumers 14, 15, 16, 17, and those supplied by the outputs 38, 40, 42 of the current sensor 34. In the pre¬ ferred implementation of the invention, the output current from the current sensor 34, which is proportional to the input at the conductors 18, 19, 20, 21 feeding the consumers 14, 15, 16, 17, is converted through electric resistors Rl, R2, R3 in voltage, which is a form of signal more appropriate to proc¬ essing by the electronic circuit of the energy transducer 47.

According to a preferred embodiment of the in¬ vention, this electronic circuit 47 is responsible for multi¬ plying the current and voltage signals, for its integration

and for the generation of energy pulses. These energy pulses are sent until the RCM 26 through bus bar 33, which connects all the ETMs 25, 28, 29, 30, 31 thereto.

Still acoording to the preferred embodiment of the invention, the output 53 of the electronic circuit of the transducer 47 consists of electric pulses representing, in a discrete manner, suitable to its processing by the RCM 26, the energy delivered to the consumer 14, 15, 16, 17.

Still according to the preferred embodiment of the invention, a visual output is provided for the accounting sig¬ nal 53 of the consumed energy, through the light emmiting di¬ ode D3. In this manner, individual calibration and monitoring procedures for each ETM 25, 28, 29, 30, 31, including the cen¬ tralized measuring, registering, reading and billing equipment 10, which is installed and operating, can be easily imple¬ mented.

Still according to the preferred embodiment of the invention, the energy transducer 47 electronic circuit is based on an integrated circuit dedicated to the consumption measurement function, allowing maximum reduction of the number of electronic components of the ETM 25, 28, 29, 30, 31, thus reducing its cost and improving its reliability.Dedicated in¬ tegrated circuits as above mentioned are known from the state of the art and, for example, described by T.L.J. Salo in "A static Domestic Watt-Hour Meter with Custom Designed Inte¬ grated Circuit", V IEE MATES Conference Proceedings, Edinburgh, Scotland, pages 126-128, 1987; and in FR 2 555 318. Any person skilled in the art can easily recognize that the invention has other possibilities of implementation, without affecting its scope, such as, for example: a) the ETM 25, 28, 29, 30, 31 can be made in such a manner that only its current sensors remain as independent modules, as illustrated in figures 3 and 4. In this case, the secondary currents representing the electric currents of the consumers 14-17 are sent through the signal and power supply bus bar < 33 until the RCM 26. The RCM 26 would then process these currents, directly determining the electric energy con¬ sumptions, and not through the ETMs. For this processing it could be used, inside the RCM 26, electronic circuits

dedicaated to each sensor 34 or a single high speed circuit, scanning all the sensors in a time sufficiently short, so as to meet all the necessary measurement requirements. In this latter case, it could be used, for example, schemes based on microcontrollers, analog/digital converters and multiplexer analogic switches, for a centralized processing at the RCM 26, of all the signals from the sensors 34 at the MU 22; and b) the sensors 34 could be implemented, if desired, from other technologies different from the one using the toroidal transformers 43-45 used in the present invention. Some examples are resistive elements (shunt type) serially connected with the electric circuit 18-21 from the consumers 14-17, or transformers with non-tcroidal configuration (E-I type), or semicinductors based on the magnetic principle of operation (Hall effect types).

Figure 9 shows the preferred embodiment of the interconnection of the centralized measuring equipment 10, where it can be seen the RU 24 and several MUs 26, and the interconnection means 23 formed by coaxial cables 23' ' and BNC type connectors 23', through which the RU 24 communicates with the MUs 26.

The RU 24 collects, through its interconnection means 23, the data referring to the consumption of each con¬ sumer 14-17, the consumption of the service areas, the total consumption of the branch corresponding to each MU 26 and to the total building consumption. It also collects, through the interconnection means 23, information on the operating state of each ETM 25, 28, 29, 30, 31; and it is also capable of col¬ lecting the energy pulses generated by an external energy me- ter 61, through a suitable connection (see figure 8).

The RU 24 also stores the date and hour of the ac¬ quisition of data referring to theconsumption measured by each ETM.

The implementation of the RU 24 is shown in more de- tail in figure 10. The central processing unit 63, consti¬ tuted by a microprocessor, EPROMs and RAMs, is responsible for the collecting of data stored at the MUs 26, through its com¬ munication circuit with the MUs 60. This circuit includes a BNC type connector.

The data stored at the RU 24 can be presented to an external user as follows:

1) through a display 62, which is controlled by the central processing unit 63 via the display control circuit 64.

5 The user can visualize the data in an non-automatic manner, through the display 62 using a keyboard and/or control buttons 65 on the RU 24. The keyboard and/or pannel buttons control circuit 66 send to the central processing unit 63 instructions referring to the operation desired by the user. The operation 10 instruction specifies the data to be shown at the display 62.

2) through a portable reader/programer 67, which communicates with the RU 24 via a communication circuit with the reader/programer 68. The connection 73 can be implemented through an optical or infrared connector. The reader/programer

15 67 is an intelligent device, capable of carrying out the auto¬ matic collection of all the data stored at the RU 24.

The RU 24 id provided with a clock/calendar circuit 69, which is used for registering the date and time of the last data acquisition successfully carried out.

20 Finally, the RU 24 is provided with a power supply

71, responsible for the feeding of all the circuits, and an auxiarily supply circuit 70, which is responsible for the the supplying of electric energy only to the central processing unit 63 RAM and to the clock/calendar circuit 69, in the event

25 of an energy failure at the main supply (coming from the elec¬ tric energy distribution network).

The RU 24 also contains a supply failure detector 72 which, upon electric energy shortage, sends a signal to the central processing unit 63, so that it can take the necessary

30 measures not to loose the stored information.

Figure 9 illustrates the preferred implementation of the invention with regard to the RCM 26.

The RCM 26 is implemented through a microcontroller 75, EPROMs 77 and non volatile RAM 78, an interface 76 for

35 communication with the RU 24, and a system for multiplexing the energy pulses 79 from the data, signal and power supply bus bar 33. The RCM 26 also contains an energy failure detec¬ tor 74, which signalizes the possible occurrence of this type of failure to the microcontroller, so that it can take the

necessary steps for the consumption data to be saved.

The microcontroller 75 of the RCM 26 collects, in groups of 8, and through the multiplexing system 70, the en¬ ergy pulses for accounting purposes. The counting of the pulses is stored at the non volatile RAM 78.

The RCM 26, whenever requested by the RU 24, trans¬ mits thereto the contents of its non volatile RAM 78, via the communiaction interface 76.

The complete scope of this invention is determined only by the attached claims.