AU711801B2

AU711801B2 - Electricity control system with pre-payment

Info

Publication number: AU711801B2
Application number: AU16622/97A
Authority: AU
Inventors: Alain Gilot
Original assignee: Schneider Electric SE
Current assignee: Schneider Electric SE
Priority date: 1996-03-29
Filing date: 1997-03-27
Publication date: 1999-10-21
Anticipated expiration: 2017-03-27
Also published as: FR2746942B1; GB9704051D0; PT101985A; ZA972540B; GB2311641B; AU1662297A; PT101985B; GB2311641A; FR2746942A1

Description

MiUM II 2a(5(91 Regulation 3.2(2)

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Invention Title: ELECTRICITY CONTROL SYSTEM WITH PRE-PAYMENT The following statement Is a full description of this invention, including the best method of performing it known to us ELECTRICITY CONTROL SYSTEM WITH PRE-PAYMENT The invention relates to an electricity control system with pre-payment comprising electricity management means comprising means for measuring the electrical power delivered to a user, means for entering an encrypted code by means of an operational key comprising information representative of a tariff index, means for entering an operational key change code comprising information representative of an operational key, means for storing the operational key, means for decrypting the encrypted code by means of the stored operational key, S" means for storing a power limit value.

Electricity control systems with pre-payment are known wherein each user has a management circuit connected to a circuit for measuring the electricity used and to a switch or a circuit breaker to interrupt the user's electricity supply when the amount of an electricity credit, stored in the management circuit and reduced as and when electricity is consumed, has been used up. The amount of the credit can be modified by entering a pre-payment code into the management circuit. In known systems, this code is entered either via a keypad or by means of a magnetic card, or by means of an electronic chip token.

Everyday operation of these systems can therefore be carried out without any operations having to be performed on site by a technician to read the electricity S. consumption. The parameters of these systems can also be set by means of codes carrying technical data instead of electricity credit. It is therefore also possible to modify the technical operating conditions of these systems with having to send a technician, and in particular to adjust the maximum power level delivered by these systems.

The object of the invention is to improve the financial security of a system of this kind.

This object is achieved by the fact that the electricity management means comprise means for extracting and storing the tariff index of an operational key change code and means for determining and storing the power limit value from said tariff index, a plurality of tariff indexes being associated to a single power limit value.

It is thus possible to ensure the financial security of such a device when the limit of power delivered is set by an engineering code, without a technician from the electricity distributor having to do anything, this being done by the final user himself.

There is thus a coherence between the power effectively subscribed for the installation, i.e. the tariff rate used when an electricity credit is purchased by the user, and the power limit effectively used in the system.

According to a development of the invention, the electricity management means comprise means for entering a disable engineering code comprising information representative of a technical power limit value, means for disabling the association between the power limit value and the tariff index when said disable engineering code *has been entered in the system, means for using the technical power limit value as the power limit value.

The electricity management means then preferably comprise means for entering a restore engineering code, means for eliminating said disable and for determining the o power limit value from the stored operational key, in response to entry of the restore engineering code.

According to a preferred embodiment, the electricity management circuit comprises S. means for entering a credit code comprising information representative of an electricity credit, means for storing said credit when the credit code is entered, means for measuring the quantity of electricity consumed, means for reducing the amount of credit stored according to the quantity of electricity consumed, the system comprising interruption means for interrupting the electricity supply under the control of the electricity management means when the amount of the credit has been used up and when the power delivered is greater than the stored power limit value, the electricity management means comprising disabling means to disable, under predetermined conditions, interruption of the electricity supply when the power delivered is greater than the stored power limit value.

Other advantages and features will become more clearly apparent from the following description of an illustrative embodiment of the invention given as a non-restrictive example only and represented in the accompanying drawings in which Figure 1 represents an electricity control system with pre-payment according to the prior art, in which the invention can be implemented, Figures 2 to 5 illustrate particular embodiments of processing flow charts for implementation of the invention in a system according to figure 1.

The electricity control system with pre-payment of figure 1 comprises a management circuit 1 and a switch 2. The switch 2 comprises contacts 3 fitted on power supply lines L1 and L2 designed to supply electricity to a user. Opening of the contacts 3 is performed by a relay 4 of the switch 2 under the control of the management circuit 1.

The management circuit 1 comprises a measuring circuit 5 connected to a microprocessor-based processing circuit 6. The measuring circuit 5 can comprise current sensors, and possibly voltage sensors, fitted on the lines L1 and L2, the *processing circuit 6 then being able to calculate the electrical power delivered to the user and the electricity consumed. Alternately, the measuring circuit 5 can comprise an electricity meter of known type disposed in such a way as to measure the electricity supplied to the user by the power supply lines L1 and L2.

In the management circuit 1, the processing circuit 6 is connected to a memory 7, a display circuit 8 and a keypad 9. An electricity credit balance C is stored in the memory 7. The processing circuit 6 decreases the amount of this electricity credit balance according to the amount of electricity used W, the information necessary for measurement and/or calculation of the quantity of electricity used being supplied to the processing circuit by the measuring circuit 5. The amount of the stored credit balance can be modified by means of a code entered via the keypad 9 accessible to the user. The display circuit 8 enables the user to be informed of the amount of the stored credit balance, i.e. the remaining electricity credit.

When the amount of the credit stored in the management circuit has been used up, the processing circuit 6 operates the relay 4 so that the latter opens the contacts 3, causing the electricity supply to the user by the lines L1 and L2 to be interrupted.

In known devices, entering a credit is achieved by means of a credit code. This code is encrypted to prevent fraud. The credit code comprises in particular information enabling the management circuit 1 of the user to be identified, information concerning the amount of the credit paid and additional information designed to ensure the security of the transaction with the electricity distributor. This additional information indicates in particular the date of purchase of the electricity credit token, the link between the management circuit and the electricity distributor.

It is moreover also state of the art to configure the management circuit by entering codes, called engineering codes. One of the engineering codes notably enables the power limit value of the system to be determined. In practice, the engineering code, which is encrypted, comprises information representative of a power limit value PIt.

This power limit value PIt is stored in the memory 7 of the management circuit 1 when the installation is started up by entering the appropriate engineering code by means :of the keypad 9. This limit can be subsequently modified by entering a new engineering code for example when a change occurs in the conditions of use of the *l*"installation associated to the management circuit.

In known systems, the management circuit 1 compares the measured power P to the limit value Pit and causes opening of the contacts 3 when P is greater than Pit.

An operational key comprising information representative of a tariff index is stored in the management circuit when the system is started up. This operational key, known to the electricity distributor, is used for encrypting the credit codes and the engineering codes supplied to the user. When a code is entered in the management circuit 1, it is decrypted by means of the operational key stored in the circuit. If the stored key does not correspond to the key used for encrypting the code, decrypting cannot take place and the code is rejected. It is thus possible to limit fraud.

As represented in figure 2, in normal operation, the processing circuit 6 checks, in a stage Fl, the existence in the memory 7 of an electricity credit C of an amount which is not zero. If the credit amount has been used up (C then the processing circuit proceeds to open the contacts 3 of the switch 2 during a stage F2. To do this, the processing circuit 6 orders excitation of the relay 4 which opens the contacts 3. To supply his installation again, the user has to reclose the switch 2 manually. However, any closing of the contacts before a new electricity credit, which must not be zero, is entered in the management circuit 1 by means of a credit code automatically leads to the contacts 3 opening again.

If a non-zero electricity credit C exists, the processing circuit goes on to a stage F3 of measuring the value P of the power delivered from the values supplied by the measuring circuit. Then, in a stage F4, it compares P with the value PI stored previously in the memory 7. If P is greater than P1, i.e. if the measured power P exceeds the power limit value PI, the processing circuit 6 proceeds with the stage F2 of opening of the contacts 3. Alternately, opening of the contacts can in this case be replaced by a load-disconnection function under the control of the management circuit 1.

When the measured power P is lower than or equal to PI, the processing circuit goes on to a stage F5 of measuring the quantity of electricity consumed W. This electricity o quantity can be calculated by the processing circuit from the current, and possibly the o. 'voltage, values supplied by the measuring circuit 5. Alternately, the value W or a value representative of the electricity consumed can be supplied to the circuit 6 directly by the measuring circuit 0 In a stage F6, the amount of the stored electricity credit C is then reduced by the amount of electricity consumed. The remaining credit C can then be displayed on the display circuit 8 (stage F7).

i. In known devices the power limit value PI used by the system is the limit value Pit supplied to the management circuit by an engineering code.

,To improve the financial security of the system, the power limit value PI is linked to the tariff index of the operational key used by the management circuit for decrypting the different codes.

This link is performed by the management circuit and is updated when an operational key change code is entered in the management circuit.

Processing of an operational key change code is more particularly illustrated in figure 3.

After a stage F8 of reading and validating the code, which uses the previous operational key to decrypt the latter, the processing circuit 6 extracts the tariff index from the code in a stage F9. Then, in F10, it determines from this tariff index and 6 stores a power limit value Pli associated to the tariff index. Then, at Fl 1, it stores in the memory 7 the value Pli as the power limit value PI. The value Pli extracted from the new operational key and linked to the tariff index contained in this key thus determines the power limit value PI taken into account by the management circuit during the stage F4 of figure 2 to interrupt the electricity supply if the power delivered is greater than PI. A stage F12 of display of the new value of PI can be introduced after the stage F11.

In a preferred embodiment the tariff index is formed by a two-figure code. The power limit value Pli associated to the tariff index is preferably expressed in kVA. An example of correspondence between the tariff index and the value Pli is provided in the table below: Pli (kVA) Tariff index Number of associated tariffs 1 10 to 19 2 20 to 29 3 30 to 39 S•.4 40 to 49 5 50 to 59 6 60to69 7 70 to 79 8 80 to 89 9 90 to 99 13.8 00 to 09 It is apparent from this table that several tariff indexes are associated to a single power limit value Pli. In the example above 10 tariff indexes, i.e. 10 different tariffs, are associated to a single limit value. As an example, a first tariff can be the normal tariff, whereas a second tariff is reserved for farmers, a third tariff reserved for needy people, the other tariffs being able to be attributed according to other criteria. Each of these tariffs has corresponding to it a different tariff index and a different price.

In the table, the limit value Pli corresponds to the tens figure of the tariff index when the limit value Pli is comprised between 1 and 9 kVA. For example, for a tariff index comprised between 50 and 59, the limit value Pli is equal to 5 kVA.

If on the other hand the tariff index is comprised between 00 and 09, the limit value Pli is equal to the maximum power acceptable by the system. In the example chosen this maximum value corresponds to 60A at 230V, i.e. 13.8 kVA.

Entering a disable engineering code comprising information representative of a technical power limit value Pit in the management circuit can enable the link between the tariff index and the power limit value PI to be disabled.

Figure 4 illustrates processing of a disable engineering code by the processing circuit- 6. After a stage F13 of reading and validation of the disable engineering code, a code o. M1 stored by the circuit is set to a predetermined first value, 0 in figure 4, during a stage F14. Then, in F15, the limit value Pit of the engineering code is stored as the power limit value PI. This value PI Pit will therefore subsequently be the value PI taken into account by the management circuit in the stage F4. A stage F16 of display of the new value PI can be introduced after the stage Taking the code M1 into account is illustrated in figure 3. An additional stage F17 is introduced between the stages F10 and Fl when processing of an operational key change code is performed. During the stage F17, the processing circuit checks the value of the stored code M1. If the code M1 has a second predetermined value, different from 0 in figure 3, the processing circuit goes on normally to stage F11. If on the other hand the code M1 has the first predetermined value, 0 in figure 3, the ~processing circuit short-circuits the stage Fl and goes directly on to the stage F12.

There is in this case no modification of the previously stored value PI, which thus corresponds to the last value Pit entered during the stage Entering a disable engineering code containing a power limit value Pit thus disables the association between the limit value PI and the tariff index. The stage F17 may be introduced between the stages F9 and F10, or respectively between F8 and F9, the stages F10 and F11 respectively F9 to F11 then being short-circuited if M1 0. There is therefore also in this case disabling of determination and storing of Pli, respectively of extraction of the tariff index.

To re-establish the association between the limit value PI and the tariff index, a restore engineering code is provided processing whereof is illustrated in figure 8 After a stage F18 of reading and validation of the engineering code, the code M1 is set to the second predetermined value, 1 in figure 5. Then the value Pli, which had been stored during the stage F10 at the last operational key change, is stored as the power limit value PI. In the alternative embodiment according to which the stage F17 is comprised between F9 and F10, an additional stage, corresponding to the stage of determining and storing Pli from the tariff index has to be added between the stages F19 and F20. If F17 is introduced between F8 and F9, an extraction stage of the tariff index corresponding to stage F9 also has to be added. A stage F21 of display of the new value of PI can be introduced after the stage F20. Introducing the restore engineering code then makes it possible to eliminate the disable introduced, permanently, by a disable engineering code comprising a value Pit. The processing circuit then re-establishes the link between PI and the last operational key or the last tariff index taken into account by the system.

The management circuit preferably also comprises means for disabling interruption of the electricity supply when the power delivered P exceeds the stored limit value Vo PI. To do this, as represented in figure 2, a stage F22 is introduced between the 6*o stages F3 and F4. During this stage F22, the processing circuit checks the value of a code M2. If the code M2 has a first predetermined value, different from 0 in figure 2, the processing circuit goes on normally to the stage F4. If on the other hand the code M2 has a second predetermined value, 0 in figure 2, the processing circuit short-circuits the stage F4 and goes directly on to the stage F5. Disabling of interruption of the electricity supply then takes place in this case when P is greater :i than PI.

The code M2 is preferably supplied to the management circuit by means of a special engineering code. It is also possible to provide manual means, such as microswitches to modify this value. Naturally, in the latter case, these microswitches must not be accessible to the user and the value of M2 must only be able to be modified by an approved fitter. Sealing and padlocking devices can be used for this purpose.

8a "Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

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Claims

1. An electricity control system with pre-payment comprising electricity management means comprising: means 6) for measuring the electrical power delivered to a user, means for entering an encrypted code by means of an operational key comprising information representative of a tariff index, means for entering an operational key change code comprising information representative of an operational key, means for storing the operational key, means (F8, F13, F18) for decrypting the encrypted code by means of the stored operational key, means for storing a power limit value (PI), a system characterized in that the electricity management means comprise means (F9) for extracting and storing the tariff index of an operational key change 9999 .code and means (F10, F11) for determining and storing the power limit value (PI, Pli) from said tariff index, a plurality of tariff indexes being associated to a single power limit value (Pli).

2. The system according to claim 1, characterized in that said tariff index is formed by a two-figure code.

3. The system according to the claim 2, characterized in that the power limit value (Pli, Pit, PI) is expressed in kVA.

4. The system according to claim 3, characterized in that the power limit value (Pli, PI) corresponds to a figure representative of the tens of the tariff index for a power limit value comprised between 1 and 9 kVA. The system according to claim 3, characterized in that the power limit value (Pli, PI) is equal to the maximum value acceptable by the system when the tariff index is comprised between 00 and 09.

6. The system according to any one of the claims 1 to 5, characterized in that the electricity management means comprise means for entering a disable engineering code comprising information representative of a technical power limit value (Pit), means (F14, F17) for disabling the association between the power limit value (PI) and the tariff index when said disable engineering code has been entered in the system, means (F15) for using the technical power limit value (Pit) as the power limit value (PI).

7. The system according to claim 6, characterized in that the electricity management means comprise means for entering a restore engineering code, means (F19, F17, F20) for eliminating said disable and for determining the power limit value (PI) from the stored operational key, in response to entry of the restore engineering code.

8. The system according to any one of the claims 1 to 7, characterized in that the S: electricity management circuit comprises means for entering a credit code comprising information representative of an electricity credit, means for storing said credit when the credit code is entered, means F) for measuring the quantity of electricity consumed, means (F6) for reducing the amount of credit stored according to the quantity of electricity consumed, the system comprising interruption means for interrupting the electricity supply, under the control (Fl, F2, F4) of the electricity management means, when the amount of the credit has S: been used up and when the power delivered is greater than the stored power limit value the electricity management means comprising disabling means (M2, F22) to disable, under predetermined conditions, interruption (F2) of the electricity supply when the power delivered (PI) is greater than the stored power limit value (PI). DATED this 27th day of March 1997. SCHNEIDER ELECTRIC SA WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN. VIC. 3122.