Control meter with safety deactivation

Control meter for controlling the supply of services, in particular the supply of electric energy, having a support base, anchored with which is a main power supply line, and a metering group detachable from the support base and with a measurement apparatus interposed between the main power supply line and a subscriber line. A safety anchorage is provided for preventing fraudulent manipulations at the control meter and comprises mechanical means associated with the metering group and movable into a locking position for engagement with the support base when the metering group is mounted on the support base, and an interrupter for generating an activation signal upon activation by the mechanical means, wherein the mechanical means is arranged to activate the interrupter when the mechanical means is released from the locking position for detaching the metering group from the support base. The invention allows to positively obstruct acts of fraud and thus to provide a control meter which is able to permit the remote-control of the “open/closed” state in situations of fraud or rather attempted fraud and is capable of unequivocally proving the occurrence of fraud or attempted fraud.

This application is the US national phase of international application PCT/EP2005/006102, filed 7 Jul. 2005, which designated the U.S. and claims priority of EP 04014022.0, filed 15 Jun. 2004, the entire contents of each of which are hereby incorporated by reference

FIELD OF THE INVENTION

The present invention relates, in particular, to the field of the distribution of electrical energy to a plurality of subscribers distributed within the territory. The invention is, however, also applicable in more general terms to other services such as, for example, the distribution of water, gas or to tele-heating. Thus, when mention will be made in the following of distribution services of electrical energy, it is understood that the teachings of the invention are easily applicable to the distribution of other services as well.

TECHNOLOGICAL BACKGROUND

Generally, meters for measuring consumption of electric energy are located in close proximity to the loads consuming the energy, e.g. in a generally accessible area of a home of a subscriber. The control meter is usually installed between a power distribution network and a subscriber line and measures the amount of electric energy drawn via the subscriber line.

Conventionally, authorized personnel manually read counter values of the control meter in predetermined time intervals, with the readings being used for billing subscribers for the consumed electric energy.

To reduce costs associated with reading the meters, techniques have been developed for remote control of the supply of subscribers with electrical energy. General problems of this type have already been described, for example, in Italian patent No. 1 232 195, filed on Oct. 26, 1988 by the present Applicant, or in U.S. Pat. No. 4,803,632.

The approach which these and other different studies have in common can be summarized in an architecture using heterogeneous forms of communication to establish a communication between the peripheral points of the system (meters at the subscriber points), with a supervision center being mainly responsible for the control of the procedures considered in each case to be useful for attaining the objects.

Such a connection is obtained by the direct communication between the supervision center (in general a server with high processor performance) and the peripheral meters, as is described, for example, in WO 98/10299, or by interposing at least one intermediate hierarchical level in this pyramid, as is suggested in WO 98/10394. Examples of these proposals can also be found in other patents such as e.g. EP-A2-0 723 358 or WO 99/46564. The general problem area of remotely controlling the supply of electrical energy is also dealt with in the recent Italian patent application No. MI2001A.002726 as filed on Dec. 20, 2001 in the name of the present applicant

As noted above, meters are generally installed in an area accessible by subscribers and others and therefore it becomes an important issue to avoid fraudulent manipulations to the control meter aiming at drawing electric energy, which is not accounted for.

The most common ways to commit energy fraud require the removal of the metering point, the manipulation of the control meter to alter the measuring constant and/or circumventing the control meter by directly contacting the terminals the mains power supply line.

To counter these attempts of fraud, the technologies known today provide one single system consisting of mounting the apparatus for measuring the energy consumption on a support base which is closed by a lid fixed thereon by means of a seal. The discovery of the break of the seal proves the committed fraud that is then sanctioned according to the facts of the case.

This system has been considered to be sufficient in the past, when it was customary that the control meter was personally controlled and looked at by an operator at least once a month, even if only to read off the consumption. However, this system has proven to be inadequate when the energy supply companies considered the systematic control once a month of all meters in the network to be too costly and carried them out less frequently, for example, by asking each subscriber via telephone about his consumption.

At the current state of the art, which permits, as described in the aforementioned patent application No. MI2001A.002726, to remotely read the consumption and even to control the energy supply in real time, including the initiation and termination thereof, the safety system support based on a seal and the direct control of the control meter does not only become inadequate but it is even totally out of the question to propose such system.

A method and system for sensing removal of a utility meter from its socket is known from U.S. Pat. No. 5,523,559, according to which the removal of a meter can be detected by a tampering detection unit, wherein the tampering detection unit is included entirely within a base or base extension and external to the meter.

Further, a device for maintaining a device housing is known from EP 0 447 615 A1, according to which a sensor detects a position of a closure device for example used in meters for metering electricity, so that it may be detected when a housing is opened and the sensed state may be transmitted to the distributor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide for an improved detection of attempts of fraudulent manipulations of control meters.

A control meter for controlling the supply of services, in particular the supply of electric energy, comprises a support base anchored with which is a main power supply line, a metering group detachable from the support base and comprising a measurement apparatus interposed between the main power supply line and a subscriber line; and a safety anchorage comprising mechanical means associated with the metering group and movable into a locking position for engagement with the support base when the metering group is mounted on the support base; and an interrupter for generating an activation signal upon activation by the mechanical means, wherein the mechanical means is arranged to activate the interrupter when the mechanical means is released from the locking position for detaching the metering group from the support base.

Advantageously, the mechanical means further comprise a retaining spanner movable into retaining means in the support base in the locking position, to form a locking bar against displacement of the metering group of the control meter relative to the support base. The mechanical means may further comprise a locking bar mandrel cooperating with the retaining spanner and the interrupter of the safety anchorage such that the blocking/unblocking movement of the locking bar mandrel corresponds to the opening/closing movement of the interrupter. The locking bar mandrel may be arranged coaxially to the retaining spanner which, when the mechanical means is in the locking position, is urged against a seat of the support base to form a locking bar against a parallel movement of the metering group relative to the support base.

The retaining means may further comprise seats and a threaded bushing for receiving a threaded portion of the retaining spanner when the mechanical means is moved into the locking position.

Spring means may be provided, acting on the locking bar mandrel so as to move the locking bar mandrel in a direction away from the support base when the retaining spanner is released from the retaining means.

The interrupter and the mechanical means may be located substantially inside a sealed container with part of the locking bar mandrel and the retaining spanner being accessible though an opening in the sealed container; and the locking bar mandrel comprises a lid covering the retaining spanner, the retaining spanner being accessible for release from the locking position only by breaking the lid.

The interrupter may be formed by a pair of flexible metal sheets resiliently contacting each other, and the mechanical means being provided with a wing apt to interpose itself between the flexible metal sheets in the locking position.

In an alternative, the interrupter of the safety anchorage is formed by a micro-interrupter, the command button being activated by an oscillating arm moved by the mechanical means.

In another alternative the interrupter of the safety anchorage is formed by an optical transmitter and an optical receiver, forming a pair of optical devices with a transmitter-receiver coupling, and the mechanical means being provided with a wing apt to interrupt the transmitter-receiver coupling by interposing itself into the path between the optical transmitter and an optical receiver in the locking position.

Moreover, the metering group may be mountable on the support base by means of a bayonet-type attachment system with which the safety anchorage cooperates, the bayonet-type attachment system comprising a pair of hook-like members integral with one of the support base and the bottom wall of the body of the meter, and, two recessed members formed in the other one of the support base and the bottom wall of the body of the meter, facing the hook-like members, whereby the engagement of the hook-like teeth in the recessed members takes place due to a displacement of the body of the control meter parallel to the respective support base.

One of the support base and the metering group may comprise a series of resilient, fork-shaped supply terminals and the other one of the support base and the metering group comprises an opposing series of mandrel-shaped control meter input terminals for the subscriber line, whereby the anchoring movement of the bayonet-type attachment system also causes the mandrel-like terminals to be engaged in the opposing fork-shaped terminals.

The interrupter may form part of an electronic circuit that is associated with translating means to transmit the activation signal to a local control unit or remote central control, and may be arranged to irreversibly command, upon actuation, the opening of a power switch52of the subscriber side of the supply line.

The metering group may further comprise an electronic circuit for the memorization of the exchange of state of the interrupter, and may be supplied by a battery having a similar service life as the meter.

The metering group may include a measurement apparatus comprising translating means for transforming the values of the effected measurements into data to be transmitted via communication lines, and communication means associated with the translating means to perform an exchange of measurement data and possible other processing data with a remote central control connected to the control meter by means of a communication line.

The activation signal may command a local microprocessor or a microprocessor at a remote central control, provided with software for effecting the initiation and interruption of the energy supply, to interrupt the power supply to the control meter by opening the power switch.

Moreover, the software of the local control unit may provide the repetition of the control of the signal identifying the occurred actuation of the interrupter and/or of the electronic circuit (14), before emitting the command for interrupting the supply, and the repetition of the control may also provide the reset of the memorization circuit.

The invention allows to positively obstruct acts of fraud and thus to provide a control meter which is able to permit the remote-control of the “open/closed” state in situations of fraud or rather attempted fraud and is capable of unequivocally proving the occurrence of fraud or attempted fraud.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following a first embodiment of the invention will be described with regard toFIGS. 1aand1b.

FIGS. 1aand1bschematically show longitudinal sections of a control meter according to an embodiment of the invention, withFIG. 1aillustrating the control meter in the locked position andFIG. 1billustrating the control meter in the unlocked position.

FIG. 1aillustrates a control meter comprising a support base1and a metering group2. The support base may for example be fixedly mounted to a wall or control meter compartment, e.g. in a subscriber's home. The metering group2is detachably mounted on the support base1, to be removed for servicing the control meter. Supply terminals23of a power supply line20are anchored with the support base1.

The metering group comprises a measurement apparatus (not shown), interposed between the main power supply line20and a subscriber line50. The measurement apparatus operates to account for electric energy drawn by a subscriber through the subscriber line. The subscriber line50and measurement apparatus are connected to the supply terminals23of the main power supply line via control meter input terminals51and, if the measurement group is mounted on the support base at the appropriate location, the terminals23and51are in contact with one another and electric power can be drawn by loads (not shown) connected to the subscriber line50, such as appliances and similar. The subscriber line50is further controlled by a power switch52, allowing to turn on and off a power supply to the subscriber line terminals53, e.g. as controlled by a local control unit of the control meter or a remote central control operator for initiating and terminating a subscriber contract, and to turn off the power supply upon detecting an attempt of fraud, as detailed further below. The power switch52may be arranged in the metering group2, as shown inFIG. 1aor, in an alternative, the power switch52may be arranged in an external protected compartment, or in the meter itself.

The metering group further comprises a safety anchorage for ensuring that the metering group is securely mounted on the support base. The safety anchorage prevents that fraudulent manipulations of the metering group, e.g. to avoid the drawing of electric power which is not accounted by the measurement apparatus, remain unnoticed.

The safety anchorage comprises mechanical means30, associated with the metering group and movable into a locking position in a recess31of the support base, for locking engagement with the support base when the metering group2is mounted on the support base1, i.e. the mechanical means can only be introduced into the recess31, if the metering group2is properly positioned on the support base1.

Further, the safety anchorage comprises an interrupter40for generating an activation signal upon actuation by the mechanical means30, wherein the mechanical means activates the interrupter when the mechanical means is removed from the locking position in the recess31, e.g. in an attempt to detach the metering group from the support base.

InFIG. 1athe mechanical means30is shown locked in the locking position and the switch40is shown in a non-activated position, indicated by the depressed switch element41, being held in a depressed position between the mechanical means30and the interrupter40. The switch element41can for example be resiliently urged by a spring in an upward direction inFIG. 1awhile being held in a depressed position by the fact that the mechanical means30is in the locked position.

Furthermore, in the locking position shown inFIG. 1a, the power switch52of the subscriber line50is maintained closed, and electric power can flow from a supply network to the loads connected to the subscriber line50, to be measured by the measurement apparatus.

The mechanical means30can for example be a retaining spanner or bolt with a threaded portion, the threaded portion for insertion into a threaded bushing in the recess31. Thus, to bring the mechanical means30into the locked position, simply a screwdriver could be used.

In the example shown inFIG. 1ait is the flat-shaped head of the mechanical means30which functions as a means to keep the switch element41in a depressed, non-activated position, however, any other means for holding the switch portion in this position could be used, such as any other protrusion at the mechanical means30or element to maintain the interrupter in the non-activated position, when the mechanical means is in the locked position.

Turning toFIG. 1b, showing the control meter in the unlocked condition, the mechanical means30is removed from the recess31in the support base, and with the release operation the interrupter is activated, as indicated by the upward moved switch element41. For example, when the mechanical means30is removed from the recess31, a spring may move the switch element41in an upward direction, activating the interrupter40.

It is an important feature that only with the mechanical means30in the position shown inFIG. 1b, i.e. removed from the recess31in the support base, the metering group2can be removed from the support base1.

Further, with the release operation of the mechanical means30the interrupter40is activated and a corresponding activation signal is generated. The activation signal indicates that someone attempts to remove the metering group from the support base and it can appropriately be processed.

In the example shown inFIG. 1b, the activation signal is used to command an opening of the power switch52of the subscriber line50via a transmission line42, turning off a supply of electric power to the subscriber line terminals53and thus to the external portion of the subscriber line and therewith to the subscriber. The interrupter may be arranged to irreversibly command, upon actuation, the opening of the power switch52of the subscriber line. Accordingly, fraud by drawing electric energy from the subscriber line terminals53without being fed through the measurement apparatus is prevented.

The power switch52may be a two-stage switch with a lever for manual activation/deactivation of the power supply and with a switch element driven by the interrupter for enabling/disabling the manual activation of the power supply. Further, the power switch52may form part of a fuse device for deactivation of the power supply in case of over current, or may be constituted by an element for triggering the fuse device.

In addition thereto, or as an alternative, the activation signal may also be forwarded to a local control unit or remote central control via a transmission line for further processing. The remote control center may also be used to remotely control the power switch52to open/close the subscriber line. It is noted that the remote control center may also control the power switch52to initiate or terminate a utility supply contract.

Still further, the activation signal and further data in association therewith, such as a time stamp of the occurrence of the activation signal, a counter value of the measurement apparatus and similar may be stored in non-volatile memory means in the local control unit of the control meter and/or at the remote control center.

In an alternate embodiment it may be preferred to irreversibly open the power switch52upon a first activation of the interrupter so as to prevent closing the power switch52upon again mounting the metering group on the support base. Further, a reset may preferably be devisable only by an operator via the remote control center or a similar entity.

Preferably, the safety anchorage is not accessible from the outside of the metering group, i.e., securely housed within a sealed casing of the metering group. This avoids access to and fraudulent manipulation of the safety anchorage in an attempt of unauthorized drawing of electric energy.

The interrupter, while inFIGS. 1aand1bshown as a micro-switch, can be of any type suitable for detecting a removal of the mechanical means30from the recess31in the support base.

Still further, whileFIGS. 1aand1bshow a recess in the support base for receiving the mechanical means30, in alternative embodiments any other means for locking engagement with the mechanical means may be devised. For example, the support base may be provided with a protrusion extending into the metering group when mounted on the support base, and the mechanical means30may be brought into locking engagement with this protrusion. Thus, many different arrangements are possible, and the invention is not limited to the exact mechanical arrangement shown inFIGS. 1aand1b.

In the following a further embodiment of the invention will be described with regard toFIG. 2.

FIG. 2shows a diagrammatic, exploded view in perspective of a control meter, particularly illustrating elements of a safety anchorage.

The control meter ofFIG. 2comprises a support base1which can be attached to the wall, for example, by means of a series of V dowel-type screws in a manner known in the art. The support base includes an end portion and terminals of a main power supply line, e.g. operated by an energy providing organization, to allow the drawing of energy by a subscriber

Further, the control meter comprises a metering group2comprising a box-like sealed casing accommodating the elements of the control meter for measuring operations. The sealed casing prevents access to the elements of the control meter for safety reasons, e.g. to prevent electric shock, and for security reasons, i.e. to prevent fraudulent manipulations to the meter. The metering group2includes a measuring apparatus for measuring a consumption of electric energy by the subscriber via a subscriber line connected to the terminals of the main power supply line through the metering apparatus, as known in the art.

Further, the metering group may include translating means for transforming the measured values of the effected measurements into data and transmitting means for exchanging data with a remote control center by means of an communication line, e.g. for remote accounting at the remote central control and subscriber billing. Further, the control meter preferably comprises a remotely operable device for interrupting/reactivating the power supply circuits. For example, the subscriber line power switch52may be remotely operable via a command from the remote control center, in addition to being operable via the interrupter.

The metering group2is mountable on the support base1by means of a bayonet-type attachment system or any other attachment system using screws, hooks and the like. In the mounted position, the subscriber can draw electric energy from the main power Supply line via the measuring apparatus and the subscriber line. In the detached position with the control meter removed from the support base, the terminals of the main power supply line are not in contact with the input terminals of the control meter, i.e., the subscriber line50and the drawing of electric energy through the metering group is not any longer possible.

However, as in the detached position the terminals of the main power supply line may be freely accessible, to prevent unauthorized drawing of electric energy, means must be provided to prevent or at least detect an unauthorized removal of the metering group from the support base.

The control meter therefore comprises a safety anchorage, shown inFIG. 2in the exploded view. The safety anchorage comprising mechanical means associated with the metering group and movable into a locking position for engagement with the support base1when the metering group is mounted on the support base1, and an interrupter for generating an activation signal upon actuation by the mechanical means. The mechanical means and the interrupter interact to generate an activation signal when the mechanical means is released from the locking position for detaching the metering group from the support base.

The safety anchorage of the embodiment ofFIG. 2preferably consists of the following elements in association with the measuring group:A hollow seat5in the form of a bushing, integral with the bottom2aof the group2.A mandrel-shaped hollow body6, slidably accommodated in the seat5. The mandrel6is more precisely provided with an axial perforation of small diameter in the lower part that enlarges in the upper part, forming a resting shoulder6a. Spring means7which urge the mandrel6upwardly.A retaining spanner8consisting preferably of a bolt, accommodated between the lower part of the axial cavity of the mandrel6, with its head resting on the shoulder6a. When the retaining spanner is loosened, its rising head pulls out the entire body6, urged by the spring means, thus releasing it from its engagement with the support base1.A retainer part15with an opening in the middle portion thereof for allowing access to the retaining spanner8below, e.g. with a screwdriver. The retainer part15is insertable into an opening of the mandrel-shaped hollow body6. Further, the opening of the retainer part15is smaller as the diameter of the retaining spanner8, such that, when the retainer spanner8is loosened, its rising head engages with the retainer part15to force the mandrel6upward, in addition to the force by the spring means.A lid9for sealing the upper part of the axial cavity of the mandrel6. The lid is retained when it is being positioned in its accommodation above the retaining spanner such that its removal entails the break of the lid.A wing10of insulating material, integral with the mandrel6and acting preferably in the radial direction towards the exterior of the mandrel6.And an interrupter11, formed by a pair of metal sheets contacting each other and being moved apart by the wing10, when the mandrel is urged downwards, the disposition and function of which will be described in more detail below.

Further, the safety anchorage of the embodiment ofFIG. 2comprises the following elements in the support base1, on the same axis as the mandrel6, to cooperate with the previously described elements in the measuring group:A seat12, constituting retaining means, for accommodating the lower end of the aforementioned mandrel6.And a seat13, constituting retaining means, for anchoring the retaining spanner8, which is comprised of an internally threaded bushing when the spanner8is a bolt.

The elements described above interact in such a manner that an activation signal is output, if the retaining spanner is removed from the seats12and13.

Briefly, the retaining spanner is movable into the retaining means, i.e. the seat13, in the locking position, to form a locking bar against displacement of the metering group relative to the support base. Further, the locking bar mandrel cooperates with the retaining spanner and the interrupter of the safety anchorage such that the blocking/unblocking movement of the locking bar mandrel corresponds to the opening/closing movement of the interrupter. Moreover, the locking bar mandrel is arranged coaxially to the retaining spanner which, when the mechanical means is in the locking position, is urged against a seat of the support base to form a locking bar against a parallel movement of the metering group relative to the support base. The retaining means may comprise a threaded bushing for receiving a threaded portion of the retaining spanner when the mechanical means is moved into the locking position.

Further, the spring means act on the locking bar mandrel so as to move the locking bar mandrel in a direction away from the support base when the retaining spanner is released from the seat13.

The pair of flexible metal sheets resiliently contacting each other forms the interrupter, and the wing is arranged to interpose itself between the flexible metal sheets in the locking position. The interrupter and the mechanical means are located substantially inside a sealed container with part of the locking bar mandrel and the retaining spanner being accessible though an opening in the sealed container; and the lid covers the retaining spanner, the retaining spanner being accessible for release from the locking position only by breaking the lid.

In an alternative the interrupter of the safety anchorage is formed by an optical transmitter and an optical receiver, forming a pair of optical devices with a transmitter-receiver coupling, wherein a signal light is transmitted from the optical transmitter to the optical receiver. Further, in this alternative the mechanical means is provided with a wing apt to interrupt the transmitter-receiver coupling by interposing itself into the path between the optical transmitter and an optical receiver in the locking position. The remaining features and operations are substantially as outlined above.

The embodiment shown inFIG. 2and its operation will now be further described with regard toFIGS. 3a,3bandFIGS. 4a,4b, respectively.

FIG. 3ashows a detail of the control meter ofFIG. 2in a cross-sectional view of the safety anchorage in the closed position.

In the cross-sectional view shown inFIG. 3a, the metering group1is mounted on the support base2and the safety anchorage is in its locked position.

In the locked position, the retaining spanner8is locked in the seat13of the support base, e.g., by way of threading and turning the retaining spanner using, e.g., a screwdriver. In this position, the retaining spanner8urges the mandrel-shaped hollow body6in a downward direction, against the force of the spring7, until the mandrel-shaped hollow body6rests on the seat12in the support base2. In this position, the metering group1cannot be removed from the support base2.

The downward movement of the mandrel-shaped hollow portion6is effected by a head portion of the retaining spanner8resting on the shoulder6aof the mandrel.

Further, with the downward movement of the mandrel6the wing portion10of the mandrel is also moved in a downward direction and eventually moved between the pair of metal sheets of the interrupter11, forcing the metal sheets out of electrical contact with one another, as the wing portion10is made of insulating material. In the position shown inFIG. 3a, the interrupter11is in the non-activated position, i.e. the “normal” position, when the metering group is mounted on the support base and the safety anchorage in the locked position.

The lid9is inserted into a top portion of the mandrel-shaped hollow body, above the retaining spanner8, to prevent access to the retaining spanner from the outside. The lid9can be removed from this position covering the retaining spanner only by breaking the lid, and therefore effectively provides a lid, as known in the art.

FIG. 3bshows a detail of the control meter ofFIG. 2in a perspective view of the safety anchorage in the closed position.

In the perspective view ofFIG. 3b, the outside of the mandrel-shaped hollow body is visible, with the wing portion made of insulating material moved into the interrupter, of which the cover11is visible. The mandrel6and the cover11rest on a support base portion2aof a casing of the metering group.

Finally,FIG. 3bshows the lid9in the inserted position above the retaining spanner.

In the perspective view ofFIG. 2, the sealed casing of the metering group is cut out for illustration purposes. An access to the safety anchorage will only be possible through a small opening, e.g., in the top wall of the sealed casing, such as with a screw-driver to turn the retaining spanner8, and insertion/removal of the lid9.

FIG. 4ashows a detail of the control meter ofFIG. 2in a cross-sectional view of the safety anchorage in the open position.

The cross-sectional view ofFIG. 4aillustrates the metering group2still in contact with the support base1, however, with the safety anchorage in an unlocked position, allowing a removal of the metering group2from the support base1. In the unlocked position, the retaining spanner8is removed from the seat13, e.g., by unscrewing the spanner using a screwdriver. With the resilient force of the spring7, the mandrel-shaped hollow body6is likewise moved in an upward direction, out of the seat12in the support base1. Further, when the retainer spanner8is loosened, its rising head engages with the retainer part15inserted into the mandrel6above the retainer spanner, as shown inFIG. 2, and the mandrel6is forced upward in addition to the force by the spring means.

When the retaining spanner8and the mandrel6are removed from their seats in the support base, the metering group2can be moved parallel and/or perpendicular with regard to the support base1, for removal of the metering group.

Further, with the mandrel-shaped hollow body6moved upwards by way of the resilient force of the spring, the wing portion10of the mandrel6is also moved in an upward direction and out of the space between the two metal sheets11. Accordingly, the metal sheets11move into electric contact with one another. The position of the wing10must be such that an electric contact between the metal sheets11is established before or at the full removal of the mandrel6and retainer spanner8from their respective seats12and13, so that it is assured that the electric contact is established at a point or before the metering group can actually be removed from the support base1. The removal of the mandrel6and retainer spanner8from their respective seats12and13is supported by the spring7and the retainer part15engaging with the rising head of the retainer spanner8.

When the metal sheets11contact one another, the interrupter switches into the activated state and outputs an activation signal. The activation signal can, e.g., be generated by a current, which is allowed to flow between the metal sheets.

This activation signal can then be output for further processing and/or can be used for opening a power switch, as detailed with regard to the embodiment ofFIGS. 1aand1b.

FIG. 4bshows a detail of the control meter ofFIG. 2in a perspective view of the safety anchorage in the open position.

The perspective view ofFIG. 4billustrates a portion of the support base1and the metering group2, with a portion of the casing of the metering group cut out for illustration purposes.

InFIG. 4b, as inFIG. 4a, the metering group2is still in a position on the support base1, however, with the safety anchorage in the unlocked position, as detailed before. The lid9is removed from the mandrel-shaped hollow body6, e.g., by breaking the lid, and the retaining spanner is removed from its seat in the support base. The resilient force of the spring7moves the mandrel-shaped hollow body6in an upward direction, and removes the wing portion10from the space between the metal sheets of the interrupter.

In the following, a further embodiment of the invention will be described with regard toFIGS. 5aand5b.

FIGS. 5aand5bshow diagrammatical longitudinal sections of a control meter according to another embodiment of the invention in the locked position and in the unlocked position, respectively.

The elements described in detail above with reference toFIGS. 2 to 4bare also illustrated very diagrammatically inFIGS. 5aand5bthat show the mandrel-shaped body6with the respective bolt8, the spring7and the threaded seat13for anchoring the bolt8.

However, differing from the previous embodiments,FIGS. 5aand5bdo not display the pair of metal sheets11forming the interrupter, but represent a variant comprised of a micro-interrupter500with an operation press-button, subject to the actuation by an oscillating arm501which is, in turn, commanded by the movement of the mandrel6.

The metering group2is mountable on the support base1by means of a bayonet-type attachment system. As is schematically shown inFIGS. 5aand5b, this system comprises, on the one hand, a pair of hook-like members2b,2cintegral with the body2(for example, formed in one piece in the cast of the bottom wall2aof the floor of the body2), and, on the other hand, two recessed members1a,1bfacing each other and formed in the support base1.

FIG. 5ashows how the group2can be mounted on the support base1, with the members2b,2cbeing vertically spaced from the members1a,1b.FIG. 5bshows, on the other hand, how the teeth2b,2cengage in the recesses1a,1b, after the group2has shifted from the top to the bottom on the support base1, thus blocking the group2on the support base1against movement perpendicularly or obliquely to the supporting wall of the support base1. The safety means according to the invention, which will be described in more detail below, is provided to prevent the group2from moving in the opposite direction, i.e. from the bottom to the top.

The support base1carries a series of terminals23(only one of which is depicted in the drawing for the purpose of simplification) to which the ends of the conductors20of the main power supply line are attached; in the case of a single phase supply line, there are only two terminals, whereas in the case of a three-phase supply line there are obviously four terminals provided. As is evident fromFIGS. 5aand5b, the supply terminal23is realized in the form of a resilient fork with which the mandrel-shaped control meter input terminal51of the supply line situated inside the body2of the control meter is apt to cooperate, engaged therewith. When the body2is only resting on the support base1(beginning of the mounting phase as illustrated inFIG. 5b), these terminals23and51are free, whereas the terminals51are engaged in the opposing terminals23when the body2is caused to shift on the support base1where it is then hooked and blocked (FIG. 5a).

As can be seen inFIG. 5a, with the safety anchorage in the locked position, the mandrel6, which is moved downward by the retaining spanner8, depresses the oscillating arm501and holds the oscillating arm501in the depressed position, holding the micro-switch in the non-activated condition.

In contrast, as shown inFIG. 5b, when the safety anchorage is in the unlocked position, i.e. the retaining spanner8and mandrels6are removed from the support base, the oscillating arm501of the micro-switch can move upward, e.g., by the force of a spring7, and the switch changes into the activated condition.

Again, the transition from the non-activated condition of the switch to the activated position of the switch must take place before the retaining spanner8and mandrels6are removed from the support base.

In the following, a sequence of steps necessary for mounting the metering group on the support base will be described with regard toFIGS. 5aand5b. A reversal of these steps allows removing the metering group from the support base.

To mount the control meter in accordance with the invention, the support base1is initially fixed, for example, to a wall, the conductors of the energy supply line are connected to the supply terminals23integral with the support base1.

Thereupon, the metering group2is brought to rest on the support base1, in the position as illustrated inFIG. 5b; then, taking into account the elements described above, the following steps are carried out:the group2is moved from the top to the bottom in the direction indicated by the arrow550inFIG. 5b, to achieve the interlocking of the group2on the support base1, similarly to a bayonet-type coupling. One also obtains at the same time the engagement of the control meter input terminals51in the supply terminals23, thus energizing the entire group2;an appropriate device such as e.g. a screwdriver, then acts upon the bolt8, which constitutes an anchor spanner, by exercising initially a pressing action from the top to the bottom, against the resistance of the spring7which is compressed thereby. Thanks to its movement perpendicularly to the support base, the mandrel6forms in practice a blocking bar, its lower end engaging in the subjacent housing seat12, thus achieving the retention of the body2against any possible shifting movement relative to the support base1; the insulating wing10simultaneously interposes itself between the pair of resilient metal sheets11in mutual contact, in order to space them from each other and to thus open the interrupter formed by the pair of metal sheets11;the screw driver is then turned to screw the bolt8into the threaded seat13as far as it will go and thus to also reliably secure the interrupter according to the invention in the safety position. As mentioned above, the engagement of the mandrel6in the seat12ensures in the first place that the group2is mechanically blocked on the support base1; in fact, the group2cannot move parallel to the plane of the support base1, resting thereupon, since it is prevented therefrom by the mandrel6which is engaged in the seat12, nor can it be raised from the plane of the support base1since this is prevented by the dents of the bayonet-type coupling.

Moreover, the engagement of the insulating wing10between the contact sheets of the interrupter11keeps the latter open which, integrated in an electric safety circuit, enables supply of a “non-operative” signal to a local control unit such as a microprocessor which belongs to the general control system of the meter, as will be described in more detail below.

It becomes clear from the description given above, taking as a starting point that any attempt of fraud requires initially that the entire body2of the control meter be removed from its support base1, then the following steps must necessarily be taken: above all, the lid9must be broken and then the retaining spanner in the form of the bolt8must be unscrewed; the mandrel6can then be expelled from the seat12due to the action of the spring7, thereby releasing its lower end from its engagement in the seat12of the support base1. However, in doing so, the wing10of insulating material also rises, departing from the metal sheets11of the respective interrupter and the latter closes. In the variant as shown inFIGS. 5aand5b, the expulsion of the mandrel6under the action of the spring7analogously removes the mandrel6from the oscillating arm501which permits the press-button502to rise again, allowing thus the micro-interrupter500to be closed. Only then is it possible that the group2is shifted on the support base1, releasing it from its bayonet-type engagement, and that the group2is lifted to access the supply terminals23.

It is important to emphasize here that this “anti-tampering” safety support based on closing the interrupter11or11aimmediately after having released the spanner6and hence even before the body2is or can be shifted relative to the support base1, is not only efficient in the case of an attempt of fraud consisting in a removal of the measuring point which requires, as previously stated, that the supply terminals23be directly accessed on the support base1, but also in the case of an attempt of fraud consisting in a manipulation of the control meter to alter the measuring constant. It must in fact be taken into consideration that this manipulation also requires that the control meter be removed from its support base1since the control meter is sealed and cannot be opened and it must be forced open at the rear part so that no clear signs thereof are apparent. It must hence be followed from this that the device according to the invention efficiently prevents the fraudulent consumption of energy in any and all possible cases.

According to an alternative, the arrangement of the hook-like members and the recessed members may be reversed, i.e., the metering group may be mountable on the support base by means of a bayonet-type attachment system with which the safety anchorage cooperates, the bayonet-type attachment system comprising a pair of hook-like members integral with the support base, and, two recessed members formed in the bottom wall of the body of the meter, facing the hook-like members, whereby the engagement of the hook-like teeth in the recessed members takes place due to a displacement of the body of the control meter parallel to the respective support base.

Still further, in an alternative the metering group comprises a series of resilient, fork-shaped supply terminals and the support base comprises an opposing series of mandrel-shaped control meter input terminals for the subscriber line, whereby the anchoring movement of the bayonet-type attachment system also causes the mandrel-like terminals to be engaged in the opposing fork-shaped terminals.

In the following a further embodiment of the invention will be described with regard toFIG. 6.

FIG. 6shows the logical functional principle of the anti-tampering system according to another embodiment of the invention.

FIG. 6illustrates the interrupter11and an electronic circuit14, e.g. a latch, EEPROM, etc, for memorizing a transition of the interrupter11from the non-activated state to the activated state. The electronic circuit14is connected to one terminal of the interrupter, the other terminal of which is connected to a main power supply (not shown) and a battery15. The battery15supplies energy for the operation of the switch11and electronic circuit14in case of a failure or disconnection of the main power supply so that the switch11and the electronic circuit14can continue to detect and memorize the actuation state, i.e. the activated or non-activated state.

The electronic circuit14is also connected to a local control unit60of the control meter and reports its actuation state or a transition of its state to the local control unit60. The local control unit may be a microprocessor unit or the main processing unit of the meter and is connected to the main power supply.

Further, the control unit60is connected to the electronic circuit14to transmit a reset signal to the electronic circuit14, for resetting the electronic circuit14from the activated state into the non-activated state.

It can be seen in the logical principle illustrated inFIG. 6that closing the interrupter11causes the activation of the electronic circuit14. It is the object of this circuit14to memorize the change of state of the signal corresponding to the opening of the interrupter11. Further, this result is immediately transmitted as a signal S16to the local control unit, where it is stored and maintained and processed until the reset R17is subsequently activated.

The uninterrupted operation of this part11,14of the circuit is ensured by the supply of the battery15which is incorporated in the circuit and preferably has a service life equal to that of the meter.

As stated above, the activation of the circuit14causes a signal S16to be immediately transmitted via the communication line to the local control unit60. The software of the microprocessor of this unit60, which receives the signal S16, processes the signal just as a command to interrupt the supply of energy, and actually causes this interruption.

In the following an exemplary operation of the control meter will be described.

At first it is assumed that the metering group is mounted on the support base and the safety anchorage is in its locking position, the switch11is in the open position, e.g. the micro-switch ofFIG. 1orFIG. 5is not activated or the wing10ofFIGS. 2-4bis inserted between the metal sheets11aand11b. Further, the electronic circuit14is considered to be in the reset, non-activated state, e.g. by way of a reset signal transmitted from the local control unit or remote control center after the control meter has been installed and/or serviced by maintenance personnel.

In this “normal” state electric energy can be drawn from the power supply line via the measuring apparatus and the subscriber line. Use of electric energy is measured and reported to the remote control center and appropriate billing statements can be generated for the subscriber.

Now it is assumed that the safety anchorage is released from the locking position, to remove the metering group from the support base. Releasing the safety anchorage causes an activation of the switch, e.g. the micro-switch ofFIG. 1orFIG. 5is activated or the wing10ofFIGS. 2-4bis removed from the space between the metal sheets11aand11b.

This closing of the switch11applies the voltage from the battery15or from the main-power supply to the electronic circuit14and sets it into the activated state. The activation of the electronic circuit is immediately reported to the local control unit and may also be transmitted to a remote central control, which may appropriately process the activation signal. The remote central control may for example be a central control facility or administrator responsible for managing a plurality of control meters.

For example, the local control unit or remote central control may command an interruption of the power supply to the subscriber supply line by means of opening the power switch52. In addition to reporting the signal, a time stamp of the activation may be recorded, a counter value of the measurement group and similar.

According to another embodiment, the circuit arrangement ofFIG. 6is further suited to avoid a report of spurious signals as tampering signals from the local control unit to the remote control center, as outlined in the following.

During normal operation, when a main power supply to the control meter is switched on and supplies electric energy to its components, upon removing the metering unit from the meter base, the switch11is closed and correspondingly an activation signal is supplied and held in the electronic circuit14and the activation signal is reported as signal S16to the local control unit60. Upon receiving the activation signal S16the local control unit60generates a reset signal R17to reset the electronic circuit14. This reset signal may be transmitted immediately upon receiving the activation signal S16or delayed by a predetermined amount of time, such as 200 ms. The reset signal17will reset the electronic circuit14into the non-activated state, however, as the switch11will be still closed due to the removal of the meter, the electronic circuit14will be activated again and the activation signal S16will be again transmitted to the local control unit60.

This cycle of transmitting the activation signal S16and resetting the electronic circuit14via the reset signal R17will therefore be repeated a plurality of times with an internal counter of the local control unit60counting the set/reset operations and, if a certain number of reset operations is reached, the tamper signal is generated. For example, a sequence of five to twenty five reset operations could be used as a limit value for the counter, and if this limit value is exceeded, the tamper signal is generated. However, it is noted that any other number of set and reset operations could be used as a limit, upon which the tamper signal is generated.

Accordingly, the circuit allows to detect a prolonged closing of the switch11, e.g. for more than one or five seconds, corresponding to the time required for the number of reset operations selected as limit before generating the tamper signal. Only if the switch11remains closed for more than this time frame, the tamper signal will be generated. Of course, this time frame will be selected such that a manipulation of the control meter within the time limit is not possible.

In the following a case will be considered where a spurious signal activates the electronic circuit14. A spurious signal could for example be generated by electromagnetic induction or any other event different from opening the switch11that activates the electronic circuit14. This spurious signal is considered to be present only for a brief amount of time, e.g. a few milliseconds or similar.

Occurrence of the spurious signal will activate the electronic circuit14and the activation signal S16will be transmitted to the local control unit60. Upon receiving the activation signal S16, the local control unit60will transmit a reset signal R17to the electronic circuit14, to reset the electronic circuit14. As the spurious signal only has a short duration, at the time of the reset operation the spurious signal may have vanished or vanishes after very few reset operations of the electronic circuit14and thus after one or a few reset operations the electronic circuit14will again remain in the non-activated state.

Erroneous generation of the tamper signal therefore is avoided, as long as the spurious signal does not exceed the time limit or number of reset operations used as a limit value.

According to another embodiment the local control unit60is adapted to perform the sequence of reset operations, i.e. to transmit the reset signal R17to the electronic circuit14, only in case the main power supply is switched on without an interruption. This prevents an unauthorized person from deliberately switching off the main power supply to the meter, in an attempt to avoid detection of closing the switch11when removing the metering unit from the base.

This also prevents an unauthorized person from removing the meter unit from the support base during a power outage, e.g. when for maintenance reasons the electric network is down.

In this case it is considered that the main power supply is switched off and thereafter the metering unit is removed from the base. As the switch11is connected to the battery15, removing the metering unit from the base during the absence of the main power supply, will also activate the electronic circuit14, and, since the electronic circuit14is also connected to the battery15, the electronic circuit14will hold its activated state.

Moreover, after again switching on the main power supply, the local control unit60, detecting the power outage, refrains from transmitting the reset signal R17to the electronic circuit14, in order to avoid resetting the electronic circuit14, for example if the switch11is again open before turning again on the main power supply.

In this case the local control unit60will only operate to detect the activation signal S16from the electronic circuit14and directly report the tampering signal to the remote central control.

Further, after detecting the end of the power outage, the control meter may resume the operations to suppress spurious signals, i.e. the sequence of reset operations, if upon the end of the power outage the activation signal S16was not detected.

According to another embodiment, in order to further avoid the unintended transmittal of a tampering signal due to spurious signals occurring during a short failure of the main power supply, the local control unit60is adapted to only refrain from transmitting the reset signal R17in the presence of an absence of the main power supply of more a certain amount of time, for example one or five seconds, i.e., a time limit too short for removing the metering unit from the base, manipulating the metering unit and reapplying the metering unit to the base. Thus, occurrence of spurious signals activating the electronic circuit14during the absence of the main power supply will not lead to the transmission of a tampering signal to the remote central control, thus avoiding erroneous reports of tampering attempts during short absence of the main power supply.

In the following a further embodiment of the invention will be described with regard toFIG. 7.

FIG. 7shows a flow diagram of operations carried out at the local control unit of the control meter to detect tampering with the control meter during a power-on and/or power-off situation, for example by the circuit arrangement shown inFIG. 6.

In a first operation701the local control unit determines whether a power-off condition was present. A power-off condition could for example be the failure or deliberate turnoff of a main power supply or could be any other interruption of the power supply to the local control unit. A power-off condition can for example be detected by the local control unit by checking a power-on flag stored in a memory of the local control unit, the power-on flag being maintained during a power on condition and being cleared upon a power failure.

If in operation701it is determined that a power-off condition did not occur, i.e., that the power supply to the local control unit was continuously switched on, in an operation701aa reset counter is cleared and in an operation702it is determined whether an activation signal is received from an electronic circuit such as the electronic circuit14ofFIG. 6, the electronic circuit latching the activation signal upon removal of the metering unit from the base, i.e., when closing the switch11ofFIG. 6.

If in operation702the presence of the activation signal is detected, in an operation703the local control unit resets the electronic circuit14. The reset operation can be carried out via the signal R17shown inFIG. 6.

Thereafter, in an operation704the reset counter counting the number of times of resetting the electronic circuit is incremented. Preferably, before operations start, this counter was appropriately cleared. For example, the reset counter could be cleared before or after operation701.

Thereafter, in an operation705it is determined whether the reset counter exceeds a reset limit, such as the reset limit described with regard toFIG. 6. The reset limit is preferably selected such that the time duration of the reset operations until the reset limit is exceeded is shorter than a time period required for removing and manipulating the metering unit. For example, if such a time limit is considered to be one second and if a reset cycle of the electronic circuit has a duration of 100 ms, then the reset limit would appropriately be set to ten, as after ten reset operations the one second time limit is reached. However, this is an example only and any other reset limit could be used.

If it is determined in operation705that the reset counter exceeds the reset limit, a tamper signal is generated, indicating that the metering unit was removed from the meter base for more than the selected limit. The tamper signal can be stored in a permanent memory of the local control unit and alternatively thereto or in addition thereto can be transmitted to a remote central control, to inform an operator or power supply company regarding the removal of the metering unit. Moreover, based on the tamper signal, the local control unit or remote central control may switch off the subscriber line, as outlined before.

If in operation705it was determined that the reset counter did not exceed the reset limit, the flow returns to operation702, where it is determined whether the electronic circuit is again set, i.e. whether the activation signal is again present at the electronic circuit. The activation signal will be present, if the metering unit has been removed from the metering base, e.g., if the switch11remains closed, as in this case the electronic circuit will again be activated. However, if the activation of the electronic circuit was in connection with a spurious event, such as electric magnetic discharges, radio frequency interferences and similar, the electronic circuit will not be again activated, thus remaining in a non-activated state. If the activation signal is not present in operation702, the flow returns to operation701.

If in operation701it was determined that a power-off condition occurred, and the power supply is now again available, in an operation707a real time clock is read. The real time clock is supplied by a battery, such as the battery15ofFIG. 6, and measures the duration of a power outage at the local control unit.

In order to measure the time duration of the power outage, at the starting of the power off, a present RTC count could be frozen or memorized in a nonvolatile memory register. Provided that the RTC still continues with normal counting operations, e.g. by the battery backup, also during the power outage, a reading of the RTC value upon turning on the main power supply and a comparison with the previously memorized value provides a simple measurement of the outage duration.

Thereafter, in an operation708it is determined whether the duration of the power-off condition, i.e. the time read from the real time clock, exceeds a power-out limit. The power-out limit preferably is set to a time limit shorter than a time limit required for removing and manipulating the metering unit. For example, the power-off time limit could be set to one second, corresponding to the counter reset limit checked in operation705. However, it is noted that any other power-off limit could be selected, such as five seconds, ten seconds and similar.

If it is determined in operation708that the power-off limit is exceeded, in an operation709it is determined whether the activation signal from the electronic circuit is present. The activation signal will be present, for example if during the power-out condition the metering unit was removed from the metering base and the electronic circuit was activated during the power-off condition.

If in operation709the activation signal is present, the flow continues with operation706for generating, storing and/or transmitting the tamper signal, etc., as noted before.

If in operation709the activation signal is not present, i.e., the electronic circuit was not activated during the power outage, the flow continues with operation701.

Further, if in operation708the power-off duration did not exceed the power-off time limit, the flow of operations continues with operation701a.

Accordingly, the operations outlined with regard toFIG. 7allow an efficient determination of a removal of the metering unit from the metering base, while avoiding an erroneous detection of the removal of the metering unit due to spurious signals. Further, the operations outlined inFIG. 7allow a determination of a removal of the metering unit also during a power-out condition.

According to an alternative, the real time clock read in operation707, in an alternative to being started upon the begin of a power-out condition, could be initialized upon detecting an activation of the electronic circuit during a power-out condition.

Further, it is noted that some of the operations shown inFIG. 7are optional, and may be omitted in alternative embodiments. For example, the operations in connection with determining a power-off condition, i.e. operations701,707,708and709may be omitted.

The advantages of the present invention can be briefly summarized as follows: The following conditions are activated after the alert situation has been discovered:activation of an adequate anti-tampering alert flag according to the state of the meter, which flag can be “read” without delay by the local control unit or remote central control;sending out a command to the remotely operable device for opening a power switch in order to interrupt (or suspend) the supply of energy to the customer;inhibition of the manual closure of the power until a specific command is received from the remote central control or remote central server after confirmation of intervention by the control operator;setting of a visual flag for supervisor personnel or providing an alert icon on the local display, the icon being also a signal for the registered subscriber of the control meter in the event that the actuation should be due to unknown third parties;local visualizing, also physically, of the position taken up by the mandrel6expelled from the spring7and break of the lid9.

It is at any rate understood that the invention is not limited to the specific disposition as explained above which only constitutes an example embodiment of the invention, but that various variants are possible, all of which lie within the abilities of a person skilled in the art, without exceeding the scope of protection of the invention as defined by the subsequent claims. It should particularly be borne in mind that in the illustrated embodiment, the electrical safety signal is activated on closing the interrupter11or11a, but a modification of the mechanical system and of the electric circuit to the effect that the same result is achieved by means of a safety signal generated by opening the interrupter also lies within the capabilities of the skilled person in an obvious manner.

Further, while the above embodiments relate to the field of the distribution of electrical energy to a plurality of subscribers distributed within a territory, the invention is equally applicable in more general terms to other services such as, for example, the distribution of water, gas or to tele-heating. In this case metering components of the control meter will be appropriately replaced. For example, a valve for gas or water distribution may replace the power switch.