TECHNICAL FIELD The present invention relates to a continuity unit for industrial, professional and/or domestic users.

BACKGROUND ART As is known, continuity units are electrical devices which, when voltage from the electricity mains is absent, supply the users which are connected to them. In particular, hereinafter, reference is made to continuity units which are provided with their own batteries, and check the level of mains voltage, in order to intervene automatically if the voltage is absent, and to re-charge the batteries automatically when the conditions of intervention come to an end, in order to be ready for any subsequent emergencies.

At present, the continuity units of the type indicated are accommodated in corresponding electricity control boxes, and are connected by means of corresponding electrical lines to the electrical mains, and to the users served. These control boxes are cumbersome, and their positioning often gives rise to difficulties; consequently, their positioning is sometimes not optimum, both from the point of view of vicinity to the protected users, and from

the point of view of ambient conditions (temperature, humidity etc), for the continuity unit itself.

DISCLOSURE OF INVENTION The object of the present invention is to provide a continuity unit which eliminates the above-described problem.

According to the present invention, a continuity unit for industrial, professional and/or domestic users is provided, which is characterised in that it comprises means for standardised connection to an electrical panel.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is now described with reference to the attached drawings, which illustrate non-limiting embodiments, in which: figure 1 shows a diagram of an electrical panel which includes the present continuity unit; figure 2 shows a view of a modular unit which belongs to the present continuity unit; figure 3 illustrates the wiring diagram of a connection in parallel, between a plurality of modular units; figures 4-6 show three block diagrams relative to three different types of continuity units; and figures 7-10 show more detailed block diagrams relative to the elements in figures 4-6, for the continuity unit according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the continuity unit consists of a modular unit which is enclosed in a container, which has attachments which can be fitted onto standard profiled sections in an electrical panel, and connected by means of terminal boards to the electricity mains, to the users, and to any other modular units, on the basis of specific requirements which exist.

In this respect, reference is made to figure 1, which shows schematically an electrical panel 10, from which the closing cover has been removed. By means of standard profiles 9, in a known manner, and in general outline, the electrical panel 10 accommodates an input and output terminal board 11, a general switch unit 12; panel switches 13 for distribution of the loads, and an emergency cut-off unit 14. In addition, according to the invention, the present continuity unit 1 is fitted in the electrical panel 10.

The continuity unit 1 consists of one or a plurality of modular units 2, each of which is enclosed in a container 3 which is shown in figure 2, and is provided with a rear longitudinal attachment 4 (groove), which can be engaged by a standard profile 9. For example the container 3 can be mounted on standard profiles of type DIN 46277/3,46277/3R, 46277/1 and 46277/2. The container 3 is also provided with holes 5 for screws to clamp the electrical cables, and holes 6 for the electrical

connection cables; the container 3 also has ventilation holes 7. Each modular unit 2 can supply a unitary power level (e. g. 100 W).

Owing to the modular structure of the continuity unit 1, it is possible to connect various modular units 2 in parallel, in order to obtain the required power levels. An example of connection in parallel is shown in figure 2, in which there are provided four modular units 2, which are connected between a mains line 18 (which is connected to the electricity mains), and a user line 19, for supply to the users to be protected. In the example shown, all the modular units 2 are connected to the mains line 18; at least one modular unit 2 (on the left in the drawing) is connected to the user line 19; the modular units 2 are connected to one another by connection lines 20, and optionally, the last modular unit 2 (on the right) is also connected to the user line 19. In the case of connection in parallel of more than eight modular units 2, connection to the user line 19 every eight units is necessary.

The modularity and ease of installation of the present continuity unit, as well as the possibility of obtaining signals from the continuity unit itself, make it particularly versatile, and thus applicable to a series of different situations, such as, in the industrial or professional fields: PLCs; numerically controlled work stations; air-conditioning systems; emergency lights; special industrial applications; fire-protection safety

systems; cash registers; automatic motorway barriers; traffic-light systems; railway level-crossing controls; airport installations; radio bridges; telephony; bank automatic cash dispensers; medical, environmental and industrial analysis laboratories; clinical analysis equipment; electronic measuring and weighing equipment; petrol stations; systems to control the level of water, rivers and dams; dentists'chairs; military systems; and, in the domestic field: home computers; alarms systems; emergency lights; heating system pumps; automatic watering systems; automatic gates; sewage discharge pumps; small electrical appliances (hi-fi systems; video recorders etc); flue ventilators and smoke extractors; telephone systems; domestic automation (roller shutters, doors etc); and power supply units for campers.

In order to understand the embodiment of each modular unit 2, the structural types of the continuity units are first of all described. In detail, the continuity units which are available at present are one of three possible types, which are described hereinafter with reference to figures 4-6.

Figure 4 relates to the type which is commonly known as off-line or relay UPS (Uninterruptible Power Supply). In this type, the continuity unit comprises a battery-charger device 23, which is connected to the mains line 18; a battery 24, which is connected to the battery-charger device 23; an inverter 25, which is also connected to the

battery-charger device 23, and to the mains line 18; a commutator 26, which has a first input, which is connected to the mains line 18, a second input, which is connected to the output of the inverter 25, and an output, which is connected to the user line 19.

In this type, the users are always supplied by the mains line 18. If a loss of voltage occurs, the commutator 26, which checks the voltage level on the mains line 18 itself, obtains the energy necessary in order to supply the users, from the battery 24.

Figure 5 relates to the type which is commonly known as interactive UPS, in which the inverter 25 is always connected to the mains line 18, via a filter impedance 28 and a switch 29. According to this solution therefore, the inverter 25 is always functioning, and, in normal conditions, stabilises the voltage supplied to the commutator 26, and keeps the battery continually efficient, by acting as an AC/DC converter in relation to the battery itself. The purpose of the impedance 28 is to reduce any imbalance caused by fluctuations of the mains voltage. If the mains voltage exceeds the tolerances planned, despite the impedance 28, the inverter 25 takes the necessary energy from the battery 24. When the emergency condition is ended, the inverter automatically re-charges the battery 24.

In the solution in figure 5, the static commutator 26 disconnects the user from the inverter 25 only if the latter is malfunctioning. In practice, since the inverter 25 is always functioning, the switching time in the event of a mains failure is zero.

Figure 6 relates to the type which is commonly known as on-line (double conversion) UPS, the wiring diagram of which is similar to that in figure 4, with the difference that the battery charger 23 normally functions as a rectifier, which is supplied by the mains line 18, in order to supply the rectified current to the battery 24 and to the inverter 25, which in turn supplies it to the user line 19. In the event of the absence of voltage, the user which is connected to the user line 19 is supplied by the battery 24, via the inverter 25, and is available immediately. When the interruption ends, the battery 24 is re-charged by the rectifier 23. The commutator 26 intervenes only if the inverter 25 is faulty.

Figure 7 shows a block diagram of the battery charger 23, comprising, in cascade with one another: a diode bridge 35, which is connected to the mains line 18, via an input terminal board 34; a DC/DC converter 36, which forms a switching power supply with galvanic isolation; a current regulator 37; and a voltage regulator 38, the output of which is connected to the battery 24, which has an output 39 which is connected to the inverter 25.

A heat sensor 40 and a voltmeter 41 are also connected to the battery 24; the heat sensor 40, which measures the temperature of the battery, is connected at its output to the voltage regulator 38, in order to modify the level of regulation of the latter according to the temperature measured, such as to guarantee the maximum life of the battery itself, in a known manner; the voltmeter 41 is also connected at its input to a timer 42, which is activated by the DC/DC converter 36, and by a test device 43, which actuates further re-charging if the previous charging has failed. The test device 43 is connected to the output of the control voltmeter 41, and controls a counter 45, which counts the attempts to re-charge, and generates a test signal if there are two unsuccessful attempts to re-charge; the test signal is then supplied via an output 46 to an indicator device (not shown), which is of the LED or acoustic type.

The battery charger 23 functions only when voltage is available on the mains line 18; the energy which is necessary in order to re-charge the batteries is obtained by means of the DC/DC converter 36, which is also used to supply to all the components and devices in each modular unit 2.

The control voltmeter 41 initiates further re-charging after a pre-determined number of hours (for example 10), if the buffer voltage value required is not present; in addition, in the battery charger 23, there is control of

the voltage during the re-charging step, by measurement of the buffer voltage and re-charging current; on the basis of these values, the re-charging time is calculated; if, at the end of this period, the batteries have not reached a sufficient buffer voltage, and continue to absorb current, a pre-alarm is generated, which is cancelled if the second attempt to re-charge is successful, or, otherwise, the alarm is confirmed, as previously described.

Figure 8 shows a block diagram of the commutator 26, which is of the static type, comprising: a mains input 50, which is connected to the mains line 18; an inverter input 51, which is connected to the output of the inverter 25; a static switch unit 52, which is of the relay or thyristor type, depending on the performance required, and is connected to the inputs 50 and 51, and to an output 60, which in turn is connected to the user line 19; an actuator circuit 53, which co-ordinates the signals obtained from the exterior, and commands actuation of the static switch unit 52; a first voltmeter 54, which is interposed between the mains input 50 and the actuator circuit 53, in order to monitor the mains voltage and lock the commutator 26 if high voltage is present; a second voltmeter 55, which is interposed between the inverter input 51 and the actuator circuit 53, in order to monitor and lock the commutator 26 in the event of a fault in the inverter 25; a current sensor 57, which is interposed between the inverter input 51 and the actuator circuit 53, in order to lock the commutator 26, if a current which is higher than an

acceptable value is present; a contactor 58, which is connected to the static commutator 52, and functions only in the on-line type, in order to count the number of switching operations between the inverter 25 and the mains line 18, and vice versa; and an overload protector 59, which is interposed between the counter 58 and the actuator circuit 53, in order to generate a thermal image, and lock the commutator if the switching operations are too frequent.

The commutator has the task of connecting the user line 19 to the mains line 18, or to the output of the inverter 25, according to the existing conditions and the type used, as previously described with reference to figures 4-6. According to a first solution, the switching is carried out by means of a relay system, and takes place only if the mains voltage is absent, or is greater than pre-determined limits. According to a second solution, the inverter is on-line, and permits switching within very short times. According to a third solution, which is designed primarily to supply simultaneously to a domestic lighting system and to high domestic loads, the commutator simply monitors the mains voltage, and switches the load to the inverter, if the voltage is lacking. If the voltage is absent, the modular unit 2 emits a signal, which, when it is received by a receiver (if one is provided), which is interposed between the mains line and the users (other than lighting), interrupts the latter until the mains voltage returns to normal, whereas the lighting is supplied at a

30% level, thus acting as a substitute for emergency lights. If the signal receiver is not installed, the modular unit 2 is automatically protected without being damaged; in this case, the energy which is available is shared between the domestic load and the lighting.

Figure 9 shows a block diagram of the inverter 25, which comprises, in cascade with one another: a converter stage 64, the block diagram of which is described in detail with reference to figure 10, which is connected to an input 63, which receives the mains voltage (from the mains line 18, or from the impedance 28, depending on the type used), and to an input 65 (which in turn is connected to the output 39 of the battery charger 23), which has an output 66; a commercially available power inverter 67; an AC output filter 68; a current sensor 69 (which detects the current supplied as output to the load, and provides maximum output current protection); and a voltage sensor 70, which controls the voltage, and is connected to an output 71.

The voltage sensor 70 is also connected to the power inverter module 67, and forms an output voltage regulation loop; it is also connected to an alarm output 73, to which there also lead an overload protection unit 74 and a thermal protection unit 75. The overload protection unit 74 is connected at its input to the current sensor 69 and to the power inverter module 67, and is connected at its output to an actuator 77, which in turn is connected at its

output to the power inverter module 67. The overload protection unit 74 serves the purpose of measuring the absorption of the load, and of switching off the inverter in the event of an overload, via the actuator 77, thus acting as an ON-OFF control. The thermal protection unit 75 is connected at its input to the actuator 77; it measures the existing temperature, and generates an alarm signal if the temperature values are outside an acceptable range, such that there is a risk of incorrect functioning of the inverter 25, or even of faults. Finally, a voltmeter 78 is connected to the output of the converter stage 65, in order to check that the voltage supplied by the latter is between a minimum and maximum value, and if necessary, to generate an alarm at the output 73.

Depending on the type of continuity unit and the loads to be supplied, the inverter 25 can supply as output a variable or sinusoidal duty-cycle square-wave voltage; if the load consists only of the lighting system, by modifying the duty cycle, this makes it possible to set the required percentage of lighting (e. g. 30%), according to the anti- panic solutions currently known, with a substantial increase in the duration of the load stored in the battery 24, and reduction of the dimensions of the inverter itself.

In addition, the inverter 25 can supply as output a rectangular-wave voltage, which has a peak value which is equivalent to the peak value of the mains voltage, and an effective value such as to obtain the required percentage of lighting. This is made possible by reducing in each

output voltage cycle, the duration of the time interval in which the output voltage value itself is other than zero.

For example, if the mains voltage has a frequency which is equivalent to 50 Hz, and a period of 20 ms, for one cycle the inverter 25 acts such that the value of the output voltage is, respectively, zero for a first interval of 7 ms, which is equivalent to the positive peak value for a first interval, of 3 ms, zero once again in a second interval, of 7 ms, and equivalent to the negative peak value for a second interval of 3 ms. By this means, it is possible to obtain a reduction in the power which is supplied to the users, and, simultaneously, to obtain high voltage values for applications which require them (such as priming the ignition of gas lamps).

The inverter also makes it possible to set manually the percentage of lighting required.

The converter stage 64 is now described in detail with reference to figure 10, and comprises a DC/DC conversion unit 80, which is connected to the input 65, and operates as a voltage translator, in order to supply as output the voltage level required by the inverter 25, on the basis of the level of the battery 24; a direct voltage levelling filter 81, which is connected between the DC/DC conversion unit 80 and the output 66; a mains sensor 82, which is connected to the input 63, and checks the presence of the mains voltage; an actuator 84, of the ON/OFF type, which is enabled by the mains sensor 82, and controls the DC/DC

conversion unit 80; a first voltmeter 85, which controls the minimum and maximum mains voltage, and is connected to the mains sensor 82 and to an alarm unit, via an alarm output 86; a second voltmeter 87, which measures the voltage of the battery 24 at the input 65, and is connected to the actuator 84 and to the alarm output 86; a third voltmeter 88, which controls the direct supply voltage of the inverter 25, and is connected to the filter 81 and to the alarm output 86; and a thermal protector 90, which consists of a temperature sensor, connected to the filter 81 and to the alarm output 86, in order to check that the operating temperature of the converter stage 64 is lower than a maximum pre-determined value, and if this is not the case, to generate an alarm signal.

The converter stage 64 is a fundamental element of the modular unit 2, since it uses the most modern technologies, and makes it possible to generate using very small spaces a constant voltage, which is used to supply the inverter 25, with an output which is separated galvanically from the input mains. The galvanic separation is of fundamental importance, since it permits electrical isolation between the input and output of the converter stage 64, and thus elimination of disturbances which exist in the mains supply.

The converter stage 64 takes energy from the battery 24 only if the mains voltage is absent; it increases and stabilises the voltage of the battery 24, in order to

supply to the inverter 25, both during normal operation and during discharge. During this discharge step, the converter stage 64 monitors the battery voltage by means of the voltmeter 87, and switches off when the minimum voltage threshold is reached, in order to avoid damaging the battery.

The continuity unit described has the following advantages. Firstly, it solves the above-described problems of space, accessibility and dimensions; it also permits simple installation, and, owing to its modular nature, it can easily be adapted to contingent requirements. In addition, it comprises an entire series of monitoring and protection devices, in order to guarantee long life and reliability, and it can be provided with devices for communication with the exterior. A further advantage consists in the fact that the continuity unit can provide high peak voltage values for applications which require them, whilst outputting power which is less than that habitually absorbed by the users.

Finally, it is apparent that modifications and variants can be made to the continuity unit described and illustrated, without departing from the protective scope of the present invention, relative to the fact that the continuity unit is assembled in a container designed for DIN connection, or has a profile suitable for an electrical control panel. In particular, the battery charger 23 and the battery 24 can be outside the modular unit 2, or they can be provided externally in addition.