TECHNICAL FIELD

The present invention relates to a safety device for preventing unauthorized personnel from manually deactivating and resetting electrical equipment, such as circuit breakers and the like. PRIOR ART

It is known to use a circuit breaker, also called an "automatic circuit breaker", as a safety system for interrupting the flow of current in an electrical circuit in case of overcurrent. Overcurrents may be caused by a malfunction such as overload, or by a fault such as a short circuit. A circuit breaker is also used as protection for electrical installations in combination with a differential circuit breaker. In other cases, circuit breakers are used as isolating switches for electrical power lines. Additionally, circuit breakers are used in electrical energy measuring devices, in the present case electronic meters. In an electronic meter, the circuit breaker is housed in a container, in order to protect the electrical conductor clamp screws and other exposed parts of said electronic meter. Thus the user has free access to only the deactivation and reset lever of the circuit breaker.

The location of the electrical energy measuring device is governed by the UNI CEI EN 16001 standard and subsequent amendments, and by other regulations, which specify that the housing compartments of said electronic meters must be located outside buildings or in boundary walls. The housing compartments may be closed with locks, provided that they are approved by the electrical energy supplier. In a building containing more than one residence, such as a condominium, the electrical energy meters are located in a compartment as near as possible to an entrance, so as to be accessible to the electrical energy supplier at any time and/or in any circumstances. In most cases, the meters are housed in cabinets, for aesthetic reasons and for personal safety. The cabinets are not always locked shut and inaccessible to unauthorized persons. In other cases, the meters are mounted on a wall without any protection or guards.

Access to meters is required for resetting a circuit breaker if it has tripped as a result of an overload or short circuit.

In other cases, a circuit breaker has to be deactivated in order to carry out work on a downstream electrical circuit. According to the correct procedure, action should be taken on said electronic meter only if required by the consumer, thus avoiding the undesirable consequences of an unauthorized deactivation or reset of the circuit breaker. Unauthorized deactivation may cause problems such as the defrosting of food products, the failure of heating systems to switch on in winter, non-operation of medical apparatus, and the like. In less common cases, the electrical energy meter may be deactivated with malicious intent by third parties, to force the consumer to leave his home.

Circuit breakers are also used in public electrical installations (apartments, schools, hospitals and other public premises) and industrial installations. The installations comprise distribution boards, located downstream of the electrical energy meter, having the function of supplying electricity to one or more consumers connected thereto, or disconnecting them in case of a fault or for the purpose of maintenance. A need is felt to prevent deliberate or accidental deactivation or resetting by unauthorized personnel. Various systems are available on the market which partly overcome the aforesaid problems, including, for example, external locking systems which use a padlock to secure the actuating lever of a circuit breaker. A padlock may be maliciously removed with a bolt cutter, thus releasing the locking system. These locking systems are bulky, and in some cases do not allow the protective panel to be closed. There are other external locking devices made of plastic material which, if exposed to direct sunlight, may be subject to accelerated ageing of the material, thus losing their robustness and becoming easily removable. Furthermore, with the aforesaid locking systems, if the circuit breaker is tripped as a result of an overload or a short circuit, the lever for deactivating and resetting the electrical contacts of the circuit breaker remains externally locked in the position preceding tripping, thus misleading an observer as to the actual operating condition of the circuit breaker.

Examples of locking devices of the aforesaid type are as follows:

- ANTI-TWIST INSERT FOR CIRCUIT BREAKER HANDLER ACCESSORY in the name of SQUARE D COMPANY, US Patent 6,703,572 Bl ;

- CONVERTIBLE LOCKING ARRANGEMENT ON BREAKERS in the name of GENERAL ELECTRIC COMPANY, US Patent 6,476,698 B 1 ;

- ELECTRICAL SWITCH EXTRACTION HANDLE WITH LOCKOUT in the name of AIRPAX CORPORATION L.L.C., US Patent 6,365,851 Bl ;

- CIRCUIT BREAKER MOVABLE ACTUATOR BLOCKING AND SECURING METHOD in the name of SIEMENS ENERGY AUTOMATION,

US Patent 6,015,956;

- CIRCUIT BREAKER LOCKOUT DEVICE FOR ATTACHMENT TO SOLID SWITCH STEM in the name of BRADY USA, US Patent 5,500,495;

- MOLDED CASE CIRCUIT BREAKER OPERATING HANDLE GUARD in the name of GENERAL ELECTRIC COMPANY, US Patent 5,060, 107;

- SECURING DEVICE FOR THE SWITCH HANDLE OF A CIRCUIT BREAKER in the name of SIEMENS ENERGY & AUTOMATION INC., US Patent 4,897,515;

- PADLOCKING DEVICE marketed by SCHNEIDER ELECTRIC, manufacturer code 26970;

- MINIATURE CIRCUIT BREAKER LOCKOUTS - PIN-OUT STANDARD marketed by BRADY WORLDWIDW INC., manufacturer code 090844;

- LOCK ADAPTER marketed by ABB STOTZ-KONTAKY GMBH, manufacturer code GJF1 101903R0001 - SA1 ;

- PADLOCKING DEVICE marketed by SCHNEIDER ELECTRIC, manufacturer code A9A26970; - PADLOCKABLE ATTACHMENT FOR OPERATING LEVER marketed by LOVATO ELECTRIC, manufacturer code 1 1 SMX12710;

- LOCKING DEVICE WITH U-LOCK F.RC OP.CIR.BREAKER marketed by SIEMENS, manufacturer code 5SW3312.

BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to overcome the problems of the prior art and to provide a safety device capable of preventing the unauthorized manual deactivation and resetting of electrical contacts and electrical equipment, particularly circuit breakers and the like.

These and other objects and advantages, which will be made clearer below, are achieved according to the invention by a device having the features stated in the appended claims.

Briefly, a safety device for preventing the unauthorized manual deactivation and resetting of a circuit breaker comprises a casing, an electromechanical locking and release system for locking at least one rotatable lever for actuating the electrical contacts of said circuit breaker, an electrical contact for activating the electromechanical system, and an electronic activating device. The casing can be fastened to a circuit breaker by means of at least one fastening element. The electromechanical locking and release system comprises a solenoid, a core, a rotatable lever and at least one fastening element capable of rotationally fixing the rotatable lever of the safety device to the rotatable lever (or levers) of the circuit breaker. The electrical contact can be actuated by a mechanism of the adjacent circuit breaker. The electronic activating device comprises an electronic coding input device for activating the electromechanical system, and a socket mounted on the casing to receive the electronic coding input device.

BRIEF DESCRIPTION OF THE DRAWINGS The structural and functional features of the present invention will be clearly apparent from the following description of a few preferred, but non-limiting, embodiments of the invention. Reference is made to the attached drawings, in which:

- Fig. 1 is a perspective view of a safety device combined with a circuit breaker; - Fig. 2 and Fig. 3 are perspective views, from different angles, of the safety device of Fig. 1 ;

- Fig. 4 and Fig. 5 are, respectively, an axonometric view and a side view of the safety device, shown in an open state to illustrate the components inside it;

- Fig. 6 and Fig. 7 are two perspective views of the safety device, shown in an open state, and of an associated circuit breaker, in the deactivated and reset operating condition respectively;

- Fig. 8 is a perspective view of a detail of the safety device according to a possible variant of the invention;

- Fig. 9 is a perspective view of a locking and release system forming part of the safety device, in a deactivated operating condition;

- Fig. 10 is a perspective view of the locking and release system of Fig. 9 in a reset operating condition;

- Fig. 1 1 is a sectional perspective view of the locking and release system of Fig. 9;

- Fig. 12 is a perspective view of an open safety device from which some internal components have been removed for illustrative purposes;

- Fig. 13 and Fig. 14 are, respectively, a side view and a perspective view of a safety device in which some internal components are placed in different positions from those in the examples of Fig. 4 and Fig. 5. DETAILED DESCRIPTION

With reference to the drawings, the number 1 indicates the whole of a safety device associated with a piece of electrical equipment 2, in this example a circuit breaker 2. The safety device 1 serves to prevent the manual deactivation and resetting of the equipment 2 by unauthorized personnel. In this example, the circuit breaker 2, of conventional modular design, is of the multi-pole type formed by a plurality of single-pole circuit breakers 21. Each single-pole circuit breaker 21 has a conventional lever 22, rotatable about a horizontal axis, for actuating electrical contacts inside the circuit breaker 2.

The safety device 1 is configured to be mounted adjacent to the circuit breaker 2. The safety device 1 comprises a casing 1 1 which preferably has a shape and dimensions compatible with or similar to those of a single-pole circuit breaker 21. Advantageously, to facilitate the mounting of the safety device 1 at the side of the circuit breaker 2, the casing 1 1 has a rear mounting recess or seat 1 12 for attaching the safety device 1 to a conventional DIN guide (not shown). Depending on the intended use, and the type of electrical equipment 2 with which it is to be associated, the safety device 1 may have different shapes and dimensions from those illustrated herein, and may have attachment formations or seats which are different, or differently positioned, from those illustrated in this example.

In the present context, terms such as "front" or "rear" are to be interpreted with reference to the installed condition of the safety device. Thus, "front" indicates a part of the safety device facing a user standing in front of the safety device, while "rear" indicates a part facing a wall on which the safety device is installed.

The safety device 1 can be secured mechanically to the circuit breaker 2 by a horizontal upper connecting bar 1 1 1. The connecting bar 1 1 1 may be of plastic material. For mechanical connection to the circuit breaker 2, the upper connecting bar 1 1 1 may have a series of mechanical attachments 162.

The upper connecting bar 1 1 1 has a series of electrical connections 161 for drawing current from the mains, upstream of the circuit breaker 2, to supply the safety device 1.

The safety device 1 comprises a lever 123, rotatable about a horizontal axis, and at least partially projecting or accessible from one side, defined here as the front side, of the safety device. At least one fastening element 124, preferably in the form of a horizontal bar, fixes the lever 123 rotationally to the lever (or levers) 22 for actuating the circuit breaker 2.

In the examples of Fig. 1 and Fig. 2, the fastening element 124 is a bar with a C-shaped cross section, mounted on the end of the lever 123 of the safety device 1 and on the end of the lever (or levers) 22 of the circuit breaker 2. Alternatively (Fig. 8), the fastening element 124 may be configured as a bar or shaft 125 passing through holes made in the levers 123 and 22. The fastening elements 124 and/or 125 serve, in the first place, to fix the levers 123 and 22 to one another rotationally, and, in the second place, to keep the safety device 1 fastened to the circuit breaker 2.

The safety device 1 comprises an electromechanical system 12 for selectively locking or releasing the lever (or levers) 22 for actuating the electrical contacts of the circuit breaker 2 in two fixed angular positions.

The electromechanical locking and release system 12 comprises the lever 123, a solenoid 121 and a core 122 translatable inside the solenoid 121. The lever 123 has a cylindrical hub 1231 in which a first and a second radial hole 1232 and 1233 are formed in positions spaced apart angularly. The holes 1232 and 1233 can be engaged, selectively and alternatively, by a front end of the core 122 when the latter is in a frontally extended or displaced position, following the de-energizing of the solenoid 121. The core 122 is received slidably in a cylindrical chamber 1265 formed in a central tubular portion 1264 of a support and guide body 1263 which is used for mounting the solenoid 121 in the safety device 1 and for housing and guiding the core 122. The solenoid 121 is mounted on the radially outer part of the body 1263. The solenoid 121 is supplied with electricity by means of electrical connections 164 running from an electronic circuit board 16, as described below. The support and guide body 1263 may have a front plate 1261 fixed to the front part of the body 1263. The front plate 1261 has a through hole 1262 aligned with the cylindrical chamber 1265. A guide and reinforcement element 1 13, fixed to the casing 1 1 , serves to prevent the outer or front part of the core 122, which projects from the body 1263, from being bent if any attempt is made to force the rotation of the lever 123 and/or the lever (or levers) 22 when the core 122 engages one of the holes 1232 and 1233. The guide and reinforcement , element 1 13 may optionally be a rigid element, of plastic material or metal for example, applied to the casing 1 1 of the safety device 1, by gluing for example. Alternatively, the guide and reinforcement element 1 13 may be formed as one piece co-moulded or moulded with the casing 1 1 (Fig. 12). The cylindrical chamber 1265 has a rear shoulder 1266 serving as an opposing wall for a spring 127 interposed between the shoulder 1266 and the rear end of the core 122. The spring 127 tends to push the core 122 into an extended or front position, towards the lever 123, in order to engage one of the holes 1232 or 1233 and keep the lever 123 angularly locked.

The casing 1 1 has a side wall 1 14 in which an opening 1 15 is formed, preferably in the form of a curved slot, which allows the passage of an activating pin 23 forming part of a (known) mechanism of the circuit breaker 2 adjacent to the safety device 1. An electrical contact 15 is positioned in the casing 1 1 , near the opening 1 15, for activating the electromechanical system 12, as described below.

The electrical contact 15 is electrically connected to an electronic circuit board 16, which is supplied with electricity from one of the electrical connections 161 branching from the connecting bar 1 1 1. According to one embodiment, the electrical contact 15 may be a strip contact (Fig. 5). In other embodiments, the electrical contact 15 may comprise a reed or a magnetoresistor, or a Hall effect sensor, associated for operation with a magnet (not shown) mounted on the pin 23. According to an alternative embodiment, the electrical contact 15 may comprise a microswitch (Fig. 13). The choice of the type of electrical contact 15 is not to be considered as limiting.

The safety device 1 is also provided with an electronic activating device 14, comprising a socket 141 for the insertion of an electronic key 142 adapted to enable the actuation of the locking and release system 12, and consequently to enable the deactivation and/or resetting of the circuit breaker 2. The socket 141 is connected electrically to the electronic circuit board 16, and comprises a decoding circuit board 141 1 for reading the electronic key 142. The decoding circuit board 141 1 stores one or more user codes for the activation of the electromechanical system 12 for locking and release 12. At least one of these user activation codes is also stored in the electronic key 142. The electronic key 142 may store, in addition to the user code, a further code with a skeleton key function.

The casing 1 1 may have at least one indicator lamp 13, connected electrically to the electronic circuit board 16. The lamp 13 can signal to the user at least one operating condition, such as the release of the lever (or levers) 22 of the circuit breaker 2.

A few operating modes of the safety device 1 will now be described.

In normal operating conditions, the lever 123 of the safety device 1 and the lever (or levers) 22 of the circuit breaker 2 are in a raised position. The spring 127 pushes the core

122 forwards. The front end of the core 122 is engaged in the second hole 1233 of the lever

123 and keeps it locked in the raised angular position (Fig. 10). Because of the fastening element 124 and/or 125, the lever (or levers) 22 of the circuit breaker 2 are locked angularly in the raised position.

In order to deactivate the circuit breaker 2, an authorized user must insert the electronic key 142 into the socket 141. The decoding circuit board 141 1 reads the electronic key 142, recognizes an activation code of the locking and release system 12, and sends an electrical enabling signal to the electronic circuit board 16. The electronic circuit board 16 starts to supply power to the solenoid 121 which, when energized, pulls the core 122 backwards, compressing the spring 127. The core 122 becomes disengaged from the hole 1233 and releases the lever 123. The electronic circuit board 16 can then cause the indicator lamp 13 to light. Thus the indicator lamp 13 informs the user that the safety device 1 is released, and therefore the circuit breaker 2 can be switched to a condition of deactivation of the electrical contacts. When the lever (or levers) 22 are lowered to the deactivation position, the lever 123 has its first hole 1232 aligned with the core 122.

Until the electronic key is inserted into the socket 141 , the electronic circuit board 16 supplies power to the solenoid 121, which retains the core 122 in the retracted position, di sengaging the 1 ever 123.

When the user wishes to reset the circuit breaker 2, he should raise the lever 123 and the lever (or levers) 22, and withdraw the electronic key 142 from the socket 141. When the electronic key 142 is withdrawn, the electronic circuit board 16 ceases to supply power to the solenoid 121 , and the core 122 is therefore pushed forwards by the spring 127. The front end of the core 122 is engaged in the second hole 1233, and the lever (or levers) 22 are again locked in the raised angular reset position.

When the circuit breaker 2 is automatically tripped, because of an overload for example, the pin 23 instantly activates the electrical contact 15. This contact sends an electrical enabling signal to the electronic circuit board 16. The electronic circuit board 16 supplies power to the solenoid 121 which, when energized, pulls the core 122 backwards, compressing the spring 127. The core 122 becomes disengaged from the second hole 1233 and immediately releases the lever 123 and the lever (or levers) 22 of the circuit breaker 2, which are free to jump downwards together into the deactivation position. The electronic circuit board 16 is designed to stop the supply of current to the solenoid 121 after a predetermined time interval, of a few seconds for example. In the lowered deactivation position, the lever 123 has its first hole 1232 aligned with the core 122. When the solenoid 121 ceases to be supplied with power, the core 122 is free to be pushed forwards by the spring 127; the front end of the core 122 is inserted into the first hole 1232, locking the lever 123 and therefore the lever (or levers) 22 in the lowered angular position of deactivation.

In order to reset the circuit breaker 2, the electronic key 142 must be inserted into the socket 141. The decoding circuit board 141 1 reads the electronic key 142, recognizes an activation code of the locking and release system 12, and sends an electrical enabling signal to the electronic circuit board 16. The electronic circuit board 16 supplies power to the solenoid 121 which, when energized, pulls the core 122 backwards, compressing the spring 127. The core 122 becomes disengaged from the first hole 1232 and from the lever 123. The electronic circuit board 16 can then cause the indicator lamp 13 to light. The indicator lamp 13 informs the user that the safety device 1 is released, and therefore the circuit breaker 2 can be switched to a condition in which the electrical contacts are reset. The levers 123 and 22 can be raised manually. When the key 142 is withdrawn, the electronic circuit board 16 cuts off the power supply to the solenoid 121 after a few seconds. In the raised reset position, the lever 23 has its second hole 1233 aligned with the core 122. When the solenoid 121 ceases to be supplied with power, the core 122 is free to be pushed forwards by the spring 127; the front end of the core 122 is inserted into the second hole 1233, locking the lever 123 and therefore the lever (or levers) 22 in the raised angular reset position. The indicator lamp 13 is switched off after a few seconds, indicating that the circuit breaker 2 has again been locked.

The arrangement of the components may vary from what has been described and illustrated here. For example, Fig.13 and Fig.14 show an embodiment of the safety device 1 in which the electronic circuit board 16 is located in a lower position in the casing 1, and the various electrical connections are therefore different from those in the configuration of Fig. 4. The safety device may be adapted for installation on the right-hand side (as in the examples illustrated here) or on the left-hand side of a circuit breaker.

Various aspects and embodiments of a safety device according to the invention have been described. It is to be understood that each embodiment may be combined with any other embodiment. Furthermore, the invention is not limited to the embodiments described, but may be modified within the scope defined by the attached claims.