ELECTRONIC CIRCUIT FOR PROTECTION OF PRODUCTIVE SYSTEMS COUPLED TO A POWER SUPPLY

Abstract: The electronic circuit coupling the energy supply to a particular productive system constituting an electric load is provided with appropriate devices which prevent the activa­ tion of the electric load whenever diversified extraneous effects occur, by shortcircuiting the load and opening the power supply to the device. By this way it is possible to avoid serious damages to the process itself and also unpleasant accidents to the operators.

Description: Electronic Circuit for Protection of Productive Systems Coupled to a Power Supply The invention relates to a circuit for protection of productive systems coupled to a power supply. The productive system, within its supply circuit, consitutes an electric load. The subject of this invention is a particular circuit whose peculiar realization, together with the disposition of the components, is able to stop any supply of the electric load, preventing in advance serious anomalies to the system (to which the circuit is appointed), and also to the operators. Usually well-known circuit breakers take care of this task but, for many technical reasons, such devices are not capable to assure the immediate intervention in interrupting the power supply circuit. Therefore serious damages may occur to the system, and it also creates a passive and expensive interruption in the particular working process of the machine coupled to the power supply because of the necessary restoration repairs to recouple the power supply. Besides there is poor safety against accidents for the surrounding operators with such prior art devices. The purpose of this invention is to obviate the mentioned serious troubles by using electronic devices, each of them being known per se, but which turn out to be advantageously innovating as regards their operative assembling, with the result of their easy and fast realization and assembly, and with the increased efficiency of intervention. Also, the devices have a longer lifetime. All this brings also an evident economical advantage, such as reduction in costs, starting from the manufacturer; therefore prices become commercially competitive. In order to achieve all these purposes and advantages and all the other ones which will be shown in the following detailed specification, an electronic circuit for protection is realized. Its basic distinctive feature is the fact that it utilizes the output stages of well-known active elements, preferably electronic switching components such as triacs coupled together, which are pushpull driven to cause their contemporaneous closing in case of various anomalities. This way they cause the interruption in the circuit of electric power supplied to the load and a short circuit over the load, assuring the safeguard of the system and also safety to the relative operators. The output phases of the active elements being coupled together serially and the output phase of the one of the active elements being coupled in parallel with the productive system, preferably in series with a fuse, provides for such advantages. The following description which further presents the invention and provides for a deepened understanding thereof by explaining an embodiment thereof, is meant to be illustrative, supplied obviously for information and therefore is not restrictive. Reference is made to the drawings, in which: - Fig. 1 is a schematic flowchart view of the circuit of protection and supply, realized according to the invention. - Fig. 2a, 2b and 3 (which relate to an identical arrangement as in Fig. 1 as regards the installation of the components) show the same circuit but in different working phases. Referring to the above mentioned Figures and restricting the detailed list of the parts to only those which are really innovating in their functionality, 1 indicates the electric feeding or supply line. On its upper branch 2 a well-known fuse 3 is set, which is provided with an inherent phase indicator 4. In the course of a vertically illustrated cable 5 connected between connection terminals of the supply, there is a gate or call device 6, below which a protection device 7 is placed, devices 6 and 7 being connected in series across the supply. Devices 6 and 7 have each a control input for supplying a control signal able to activate or bar the device. The control input of device 6 is connected via a cable 8 to a control circuit 10, the control input of device 7 is connected to cable 8 via an inverter 9. The lower branch 11 of the electric feeding line 1 is connected to a load 12, which as also coupled at a junction 13 to the above mentioned cable 5. Transistors of any kind and triacs make up the circuit, particularly the devices 6 and 7. In the circuit arrangement according to Fig. 1 which is specifically indicated, the components present an advantageous installation rationally utilizing the two active devices which are functionally and conveniently coupled in opposition and in parallel to the line. One of them, in particular the call device 6 is set to control the power supplied to load 12, receiving the signal from control circuit 10. The protection device 7, which is set in parallel with the above mentioned load 12, is also controlled by control circuit 10, but the control signal is inverted. With the specific innovating characteristic of the invention, it is evident that a short circuit occurs due to any discrepancy causing the closing of one of the two aforesaid devices (such diescrepancies originating from anomalous causes). A short cirucit is apt to blow the fuse 3, so that the output is definitively stopped and consequently the operating machine set to the productive cycle is stopped. This way serious breakage is avoided and also maximum safety to the operators is assured. In this case, with further advantage and as an important warranty, the closing of the protection device 7 prevents any electric voltage from further reaching and activating load 12, since when both devices 6 - 7 are closed load 12 is inactivated (see Fig. 3). To operate the circuit, Fig. 2 shows the on/off operation which is illustrated as the connection of a couple of known switches 15/16, which are alternatively on and off, and the functional capabilities of the devices of "call" 6 and "protection" 7, as well as load 12 either active in on phase (Fig. 2a), or inactive with reference to load 12 (Fig. 3) corresponding to off phase. As a further advantage, control circuit 10 takes care of the transitions of state of the above mentioned devices 6 and 7 and it does this extremely well, without any ambiguities, crossovers or various interferences during the transitions themselves. Obviously this system can be realized in different ways, referring to its components, in order to improve even more its functionality without therefore being beyond the limits of this invention, as it is protected by the following claims.

Claims: Electronic Circuit for Protection of Productive Systems Coupled to a Power Supply 1. Electronic circuit for protection of productive systems (12) coupled to a power supply (1), characterized by: - a pair of active elements (6, 7) being serially coupled together across said power supply (1), one (7) of said active elements being coupled in parallel with said productive system (12), and each active element having a control input; - a control circuit (10) generating a signal; - means (8, 9) for applying said signal to the control input of the other one (6) of said active elements and applying an inverted signal complementary to said signal to the control input of said one active element (7). 2. Electronic circuit for protection of productive systems according to claim 1, characterized in that said active elements (6, 7) are electronic switching components. 3. Electronic circuit for protection of productive systems, according to claim 2, characterized in that said active elements (6, 7) are triac transistors. 4. Electronic circuit for protection of productive systems, according to any of claims 1 to 3, characterized in that said other one (6) of said active elements (6, 7) controls the power supplied to said productive system (12) in accordance with said signal (on 8) and said one active element (7) shortcircuits said productive system (12) in accordance with said inverted signal. 5. Electronic circuit for protection of productive systems, according to any of claims 1 to 4, characterized that in series to the parallel arrangement of the productive system (12) and the one (7) of the active elements, further, a fuse (3) is connected. 6. Electronic circuit for protection of productive systems, according to any of claims 1 to 5, characterized in that in case of anomalies the circuit prevents any power from reaching and starting the productive system (12) and consequently assuring the maximum safeguard to the system and the safety of the operating personnel.

Inventors: BOLLITO, DOMENICO
Applicants: FASE SPA
Application year: 1984
Main classification: H02H3
IPC codes: H02H3