Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
  • H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
  • H02H3/165—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems for three-phase systems

Definitions

• the present invention relates to a protective device for electrical apparatus, machines and installations, this device protecting electric lines known as "users”, connected to power supply lines electric.
• the present invention applies to the safety of complete electrical installations. dwellings, the protection of electronic or computer systems against overvoltages, the safety of users of electrical machines or appliances in industry or in any other field of activity.
• the present invention claims to remedy these drawbacks by using a connection of all the lines to be protected between them so as to create a potential line of a determined and constant value during the normal operation of the installation to be protected, by detecting a variation in this potential relative to neutral and by the automatic and rapid cut-off of the supply to the lines to be protected as soon as a variation of said potential is detected.
• the device which is the subject of the present invention is therefore a protection device for electrical apparatus, machines and installations comprising user power lines to be protected, connected to electrical supply lines, characterized in that it comprises in combination: at least one resistance bridge connecting the user power lines and creating a fixed potential at one of its points, fixed during normal operation of the installation; an isolation means connected to this point and amplifying the potential difference between this point and an earth or neutral line; a threshold circuit connected to the output of this isolation means; a processor connected to the output of this threshold circuit; and a means of connection and disconnection of the supply lines with respect to the user power lines to be protected controlled by said processor, so that an abnormal variation of voltage on one of the power lines causes a variation of the potential at the aforementioned point, this variation being detected by the threshold circuit, which transmits it to the processor, which then causes the disconnection of the power supply lines from the user power lines.
• the operation of the device can be controlled by a digital circuit adding additional functions, and the trigger threshold can be adjustable.
• the protection can be carried out partially on certain parts of an electrical installation.
• the restarting of the installation by reconnecting the lines cut with the power supplies, can be ordered by the device within a variable memorized delay according to the number of line breaks already made.
• One of the advantages of the device according to the present invention resides in that several networks or a multitude of lines can be monitored simultaneously by an electronic circuit or detection "card" and that the digital circuit is adapted to control several detection cards simultaneously. Consequently, whatever the number of transformers, inverters or power supplies of an electrical installation, each of its lines can be monitored by the device which is the subject of the present invention. Conversely, each line can be monitored individually and in parallel with all the others.
• FIG. 1 shows a block diagram of the protection device according to the invention
• FIG. 2 shows an electronic diagram of a detection card incorporated in the device of Figure 1;
• FIG. 3 shows a flowchart of operation of this same device
• FIG. 4 shows the connection of the device of Figure 1 to an electrical distribution network
• FIG. 5 shows an electronic diagram of a detection card having the same functions as the card of Figure 2 and constituting a variant.
• power lines 1 of a user installation connected to external power supply lines 2, a ground or neutral line 3, a resistance bridge 4 connecting all the lines 1, a determined potential point 5 of the bridge 4, an isolation and amplification means 6 connected to the point 5 and to the earth or neutral line 3, a threshold circuit 7 connected to the output of the means isolation and amplification 6, a means of connection and disconnection 8 of the supply lines 2, relative to the user lines 1, connected on the one hand to the threshold circuit 7 and on the other hand to a processor 9 itself connected to a memory 10, to an interface 11 and to the threshold circuit 7.
• the resistance bridge 4, the potential point 5, the isolation means 6, the threshold circuit 7 and the connection means and disconnection 8 together constitute a detection card generally designated by 12.
• the supply lines 2 and the earth or neutral line 3 are generally lines of the supply sector, in particular of a three-phase alternating network or of a single-phase network.
• the potential point 5 is connected by the branches of the resistance bridge 4 to the lines 1 in a barycenter manner, so that its potential has a determined and fixed value, and is in particular zero, when the lines 1 carry normal potentials.
• the isolation means 6 may for example consist of a toroidal transformer, as shown in FIG. 2, or of an operational amplifier as shown in FIG. 5. This isolation means 6 amplifies the potential difference between point 5 and the earth or neutral line 3.
• the threshold circuit 7 transmits a signal when the potential difference at the output of the isolation means 6, itself an image of the potential difference between the point 5 and the earth or neutral line 3, is greater than a predetermined value.
• connection and disconnection means 8 may consist of relays, electromagnetic or static contactors or other electro-mechanical devices. It connects or disconnects the supply lines 2 with the user power lines 1.
• the processor 9 can be a computer, a microcontroller, a computer or any other computer means. It has an interface 11 allowing a dialogue between the user and the device.
• the processor 9 is programmed according to a program kept in a memory 10 to control the operation of the elements of the device.
• the interface 11 allows the connection of a display means and a keyboard. It also allows the connection of the device with a computer system or with recording means making it possible to transfer the information contained in the memory 10. This information can in particular relate to incidents occurring on the supply lines 2.
• the exceeding of the predetermined threshold by the signal leaving the isolation and amplification means 6 triggers the disconnection of the user lines 1 from the supply lines 2.
• the processor 9 orders the reconnection of the lines 1 and 2 after a delay memorized in the memory 10 and chosen by the user. In this way, an abnormal variation of voltage on one of the power lines using 1 causes a variation of the normally fixed potential of point 5, this variation being detected by the threshold circuit 7 which transmits it to the processor 9, which orders by means 8 disconnection of user lines 1 from supply lines 2.
• FIG. 2 we see an embodiment of the detection card 12. For a better understanding of the invention two networks are represented here, namely a single-phase network 13 and a three-phase network 14. A advantages of the invention is in fact that several different types of network can be protected simultaneously by the same detection card 12.
• the networks 13 and 14 each include power supply lines 2 and user power lines 1 separated by a relay 20.
• the user lines 1 of the three-phase network 14 are connected to a connector 15, also connected to earth 16 and to a toroid 51 by supply lines 17 and 18, as well as to an isolation transformer 50.
• the resistance bridge 4 is thus directly connected to lines 1 of the three-phase network 14, leaving a three-phase isolation transformer 50 'itself connected to the supply lines 2, while the isolation transformer 50 is inserted between the bridge 4 and the lines 1 of the single-phase network 13.
• the transformer 51 is a toroid placed around the two lines 1 of the single-phase network 13, with earth neutral.
• the resistance bridge 4 connects all the lines 1 to a primary 21 of a toroidal transformer 23 voltage booster, used as an amplifier.
• the secondary 22 of this transformer 23 is connected to a rectifier circuit 24.
• the output signal from the rectifier circuit 24 as well as a potential value fixed by a potentiometer 25 are brought to an opto-coupler 26 itself connected to a flip-flop 27.
• the output of the flip-flop 27 is connected by an optocoupler 28 to an amplifier 29 connected to a contactor 52.
• a connector 30 is adapted to connect the processor 9 to the detection card 12 so that the processor 9 controls the flip-flop 27 and the relays 20, and perceives the position of the contactor 52.
• the transformer 23 and the optocouplers 26 and 28 serve to isolate the different functions of the detection card 12, the transformer 23 amplifying the signal supplied by the bridge 4. An imbalance in this bridge 4 causes the appearance of 'a current flowing in point 5 and a potential across the secondary 22 of the transformer 23. This potential difference is rectified by the circuit 24 and according to the value of a threshold fixed by the potentiometer 25, the flip-flop 27 changes status and causes relays 20 to open via contactor 52.
• the isolation and amplification means 6 is constituted here by the transformer 23.
• the threshold circuit 7 is constituted by the rectifier circuit 24 and the potentiometer 25, and the connection means and disconnection 8 by the flip-flop 27 associated with the contactor 52 and the relays 20.
• the primary 21 of the transformer 23 must be adapted to operate from 1 to 2 milliamps. In this way, any insulation fault of one of the lines 1 with respect to the earth 16 is detected and causes the disconnection of the lines 1 with respect to the lines 2.
• the single-phase isolation transformer 50 makes it possible to detect the overvoltages appearing on the lines 1 and then to trigger the electrical disconnection of the lines 1 from the lines 2.
• the neutral of the primary of the transformer 50 is connected (by a conductor not shown) to the supply line 17 also connected to the transformer 51; thus there is a reference loop allowing operation of the device even if the earth connection does not exist on the side of the user installation, hence additional security.
• the torus 51 makes it possible to detect the insulation faults of the lines 1 with respect to the earth: indeed an insulation fault between a line 1 and earth 16 causes an overvoltage between the supply lines 17 and 18 of the toroid 51, an overvoltage which is detected by the threshold circuit 7.
• the torus 51 can be specially adapted to give a sensitivity of two milliamps to the device. For example, these two milliamps can, at the output of the torus 51, correspond to thirty millivolts. Such a trigger threshold provides excellent protection for people without risking tripping due to interference on the network.
• Another advantage of this embodiment is that the short-term parasites appearing on the lines 1 do not cause. no disconnection, the energy corresponding to these parasites being insufficient to trigger the operation of the opto-coupler 26.
• FIG. 3 there is seen an operating flow diagram of the device according to the invention.
• This flow chart makes it possible in particular to specify the programming of the processor 9 and the means making it possible to produce variants of the embodiment described with reference to FIGS. 1 and 2.
• the detection means 12 consists of one of the cards shown in Figures 2 or 5, the second card is however preferential (see description below).
• the autonomous power source 32 is constituted by a battery, an inverter or other generating means.
• the fault analyzer 33 analyzes in particular on the lines 1 the overvoltages, the carrier currents, the parasites, the micro-cuts, the voltage or frequency variations. These data are memorized, displayed or signaled according to their importance or their repetition.
• connection _. ⁇ of the autonomous power supply 32 and the joint disconnection of the sector 31 are for example ordered when a micro-cutoff lasts more than a second.
• a reconnection signal 36 or 38 is given, after a disconnection, within a waiting time memorized by programming.
• this delay can be variable depending on the information previously stored. For example, after ten reconnections made within a certain period, the period between disconnection and reconnection can be extended to protect the electrical systems connected to lines 1.
• detection cards 12 each connected to a given electrical system, can be connected to a single fault analyzer 33.
• the fault analyzer then stores an identification of the detection card which supplies it with signals default.
• a high resistance for example of 1 megohm, can be connected in series with an opto-coupler on lines 1.
• the opto-coupler can be connected at output with several threshold comparators set to values different, the output of the comparators being connected to an interrupt line of the processor 9.
• a low-pass filter can be added between the opto-coupler linked to the measurement of overvoltages and a comparator.
• the frequency measurement can be carried out by counting the zero crossings of the voltage of the lines 1.
• a counter linked to a clock and a comparator make it possible to easily perform this function.
• the programming means 34 is, for example, made up of a keyboard.
• an adjustable threshold may consist of the user of a field effect transistor connected to a digital-analog converter whose input is connected to the processor 9.
• Another embodiment of this adjustable threshold may consist of the use of several resistors of different values, one of these resistors being selected by a switch connected to the processor 9.
• This flow diagram and the description of FIG. 1 make it possible to produce the processor 9.
• a detection circuit 12 is connected to the lines 2.
• the processor 9 is connected to this detection circuit 12, to the earth 16 and to the connection and disconnection means 8. According to this insertion of the device into the electrical installation of a room connected to a distribution network, the reconnection is done in two stages, so that the electrical systems connected to the electrical lines 1 are protected.
• FIG. 5 represents another embodiment of a detection card 12 which can replace the one shown in FIG. 2, the application to a single-phase network here shown not being limiting.
• One of the characteristics of the invention consists in the electrical isolation of the bridge 4 and of the output of the isolation and amplification means 6, the device having a very high sensitivity thanks to this electrical decoupling. Any power supply to the threshold circuit 7 which would be common with one of the lines 1 would deteriorate this sensitivity.
• the threshold circuit 7 is electrically supplied by the toroidal transformer 23, in which the primary 21 and the secondary 22 are isolated from one another.
• FIG. 5 Other means of supplying the threshold circuit 7 electrically isolated from the bridge 4 are possible: supply by solar cell, by battery, by battery, by accumulator or by transformer.
• the supply means of the threshold circuit are constituted by a transformer, which is distinct from the isolation and amplification means 6.
• a resistance bridge 4 comprising a determined potential point, normally fixed 5 connected to the input of an operational amplifier 42, this amplifier 42 being supplied by a transformer 43 connected to the lines 2, the output of the operational amplifier 42 being connected to a converter analog-digital 44 itself connected to processor 9, which is connected by means of connection and disconnection 8.
• the amplifier 42 thus supplied constitutes the means of isolation and amplification 6.
• the processor 9 can analyze the irregularities of the potentials carried by the lines 1 thanks to numerical values. The analysis of overvoltages, micro-cuts, frequency changes is then made possible.
• FIG. 5 Other embodiments suggested by the remarks made with regard to FIG. 5 make it possible to produce other devices in accordance with the spirit of the invention. It should be noted that the device produced according to the description of FIGS. 1 to 5 can make it possible to detect electric shocks due to lightning within a radius of fifty kilometers from its point of impact.
• the interface 11 of the processor 9 also allows the output of information on a printer, or on a modulator-demodulator.
• the memorization of abnormal events occurring on lines 1 also allows the analysis of experts in the event of disputes with the electricity supplier, or in the event of damage to devices under warranty or under maintenance contract.
• each line 1 can be monitored by a specific detection card 12.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Emergency Protection Circuit Devices (AREA)
• Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
• Alarm Systems (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9409635

Family Applications (1)

Country Status (10)

Families Citing this family (7)

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• 1991
  • 1991-02-08 FR FR9101634A patent/FR2672744B1/fr not_active Expired - Fee Related
• 1992
  • 1992-02-04 HU HU9203499A patent/HUT62730A/hu unknown
  • 1992-02-04 AU AU13626/92A patent/AU647600B2/en not_active Ceased
  • 1992-02-04 HU HU9203499A patent/HU9203499D0/hu unknown
  • 1992-02-04 US US07/941,070 patent/US5390066A/en not_active Expired - Fee Related
  • 1992-02-04 WO PCT/FR1992/000099 patent/WO1992014291A1/fr not_active Application Discontinuation
  • 1992-02-04 CA CA002080133A patent/CA2080133A1/fr not_active Abandoned
  • 1992-02-04 JP JP92506003A patent/JPH05506350A/ja active Pending
  • 1992-02-04 EP EP92905885A patent/EP0524300A1/de not_active Withdrawn
  • 1992-10-07 CZ CS923055A patent/CZ305592A3/cs unknown
  • 1992-10-08 OA OA60287A patent/OA09618A/fr unknown

Non-Patent Citations (1)

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