Title of Invention

DEVICE FOR PROTECTION AGAINST ELECTRICAL FAULTS

Abstract The present invention relates to a device for protection against electrical faults comprising: measuring means for measuring a fault current, processing means connected to the measuring means, an actuator connected to the processing means and to a power supply line to bring about opening of electrical contacts, and limiting means connected to the actuator for limiting voltage surges on said actuator, a device characterized in that the actuator comprises: a first winding connected between the power supply line and a common output connected to the limiting means for limiting voltage surges, and a second winding connected between the common output and the processing means.
Full Text The invention relates to a device for protection against electrical faults comprising:
- measuring means for measuring a fault current
- processing means connected to the measuring means,
- an actuator connected to the processing means and to a power supply line to bring about opening of electrical contacts, and
- means for limiting voltage surges connected to the actuator.
Known protection devices comprise an actuator to bring about opening of electrical contacts in order to interrupt an electrical current when a fault is detected. Generally speaking, the actuator comprises a winding connected between a power supply line and a magnetic core arranged in the axis of said winding. An electronic processing circuit controls the actuator by monitoring the flow of a current in a winding. Thus, the magnetic core is moved when a control current is flowing in the winding.
As the winding is connected to a power supply line, its immunity to electrical disturbances has to be very high. Disturbances manifest themselves in particular by temporary voltage surges. It is known to use specialized components for voltage surge limiting. These components are essentially voltage dependent resistors, clipper diodes or avalanche effect diodes. However, to be really effective these components have to be associated with other components such as series resistors or other current limiting components. Such associations of components are not compatible with the small volumes generally available in electrical protection devices.
Moreover, the actuators of protection devices are intended to operate in very high voltage ranges. Associations of components are also liable to limit this operating range and to reduce the performance of the device.
Surge limiters can be used very close to the electronic processing circuit using the

Impedance of the actuator to limit the size of their components. However, during a voltage surge, a disturbance current flowing in the winding may cause movement of the magnetic core and order opening of the contacts.
Object of the invention
The object of the invention is to provide a device for protection against electrical faults having a great immunity to electrical disturbances and a small volume.
In a device according to the invention, the actuator comprises:
- a first winding connected between the power supply line and a common output connected to the means for limiting voltage surges, and
- a second winding connected between the common output and the processing means.
In a preferred embodiment, the first winding is achieved in two parts separated by an insulating shield.
Advantageously, the actuator comprises a mobile magnetic core located essentially in the first winding when the actuator is in the inactive position.
Preferably, the first and second winding have appreciably the same number of turns.
Preferably, the first and second winding have a number of turns equal to or less than 700.
In a particular embodiment, the processing means comprise a component which switches to the open position when the current flowing through this component is nil, and triggering means supplying a control signal without storage after a fault to trigger turn-on of said component, the actuator being connected to an AC power supply line.
Advantageously, the actuator can be connected to a power supply line located either up-line or down-line from the electrical contacts.

Preferably, the processing unit comprises means for tripping on a differential fault current.
In a particular embodiment, the processing unit comprises means for tripping according to the voltage of the power supply line.
Preferably, the means for tripping according to the voltage of the power supply line comprise a mechanical indicator operated by a relay connected to a winding of the actuator.
Brief description of the drawings
Other advantages and features will become more clearly apparent from the following description of embodiments of the invention, given as non-restrictive examples only and represented in the accompanying drawings in which:
- figure 1 represents a diagram of a protection device of known type;
- figure 2 represents a diagram of a protection device according to a first embodiment of the invention;
- figure 3 represents a diagram of a protection device according to a second embodiment of the invention;
- figure 4 represents a diagram of an actuator for a protection device according an
embodiment of the invention;
- figure 5 represents a perspective view of an actuator according to figure 4;
- figures 6 and 7 represent views of a support of an actuator according to figure 4;
- figure 8 represent a diagram of a protection device according to a third embodiment of the invention.
Detailed description of a preferred embodiment
The known protection device represented in figure 1 comprises contacts 1 for interrupting an electrical current in a power distribution system. The contacts are controlled by a mechanism 2 able to be actuated by an actuator 3. A processing unit 4 receives a signal representative of an electrical current supplied by a sensor 5. In this diagram, the sensor 5

is a toiroid for measuring a differential current. Ice actuator comprises a winding b connected between a conductor of a power supply line 7 and a first output of the processing unit 4. A second conductor of the power supply line is connected to a second output of the processing unit 4. The processing unit 4 is thus supplied by the power supply line via the actuator winding.
When a differential fault current is detected by the sensor 5, the processing unit 4 orders flow of a current in the winding 6 of the actuator 3 which moves a magnetic core 9. The core 9 orders tripping of the mechanism 2 to open the contacts 1.
In this diagram, the processing unit comprises an electronic processing circuit 14 which processes the signal supplied by the sensor 5 and commands a thyristors 16 connected between the first and second output of the processing unit. The power supply of the circuit 14 is provided by a power supply circuit 15 having outputs cormected to the inputs of the processing unit. The power supply circuit generally comprises a voltage step-down device and a rectifier circuit. As the power supply circuit is connected in series with the actuator, the current absorbed by said power supply circuit is very low so as not to cause tripping.
To prevent electrical disturbances in the form of voltage surges from disturbing operation of the processing unit, a varistors (voltage dependent resistor) 8 is connected between the first and second outputs of said circuit 4. However, with this diagram a disturbance can make a current flow which is sufficient to move the core and command opening of the contacts.
In a device according to an embodiment of the invention, the actuator comprises two windings connected in series and comprising a common output or a winding with a mid¬point. The common output or the mid-point is connected to surge limiting means.
A device according to a first embodiment of the invention is represented in the diagram of figure 2. In this diagram the actuator comprises a first winding 10 connected between a first conductor of the line 7 and a common output 11, and a second winding 12 connected between said common output 11 and an output of the processing unit 4. The voltage


dependent resistor 8 is connected between the common output 11 and a second conductor of the line 7.
In this embodiment the varistor 8 can be of small dimension as the impedance of the first winding limits the disturbance current. Thus, for transient disturbances, the first winding and the voltage dependent resistor are connected in series, the first winding limiting the current in the voltage dependent resistor and the voltage dependent resistor 8 limiting the voltage applied to the input of the processing unit 4. The current flowing in the first winding only does not induce sufficient electromagnetic force to move the core of the actuator. The second winding in series with the first winding enables a sufficient force to be induced to command movement of the core of the actuator when the processing unit allows a tripping current to flow in the two windings.
A device according to a second embodiment of the invention is represented in the diagram of figure 3. In this diagram, the processing unit has the first output which connects the thyristor 16 to the second winding 12 and also comprises a third output which connects the power supply circuit 15 to the varistor 8 and to the common output 11 of the actuator. An impedance 17 formed by a capacitor and a resistor generates a voltage drop between the varistor 8 and the power supply circuit 15. This impedance 17 can also be integrated in the processing unit or form part of the power supply circuit.
A detailed diagram of the actuator is represented in figure 4. In this diagram, the first winding 10 is achieved in two parts 10a and 10b separated by an insulating shield 13. This arrangement prevents electrical arcing between the turns of the winding when the disturbances present high voltage surges, for example voltages of several kilovolts.
Furthermore, when the disturbances are strong, the first winding can induce electro¬magnetic disturbances in the second winding. Voltages thus generated in the second winding may disturb the processing unit 4. To prevent inductions from occurring from the first winding onto the second winding, the mobile magnetic core of the actuator is arranged so as to be located essentially in the first winding when the actuator is in the inactive position.

A view of an actuator according to figure 4 is represented in figure 5. In this figure, the actuator comprises a support 18. Views of a support 18 of an actuator are represented in figures 6 and 7.
To optimize manufacture of the actuator, the first and second winding preferably have appreciably the same number of turns. Advantageously each winding has a number of turns equal to or less than 700.
The actuator being connected to an AC power supply line, the processing unit advantageously comprises a control component of the actuator which switches to the open position when the current flowing through this component is nil, and triggering means supplying a control signal without storage after a fault to trigger turn-on of said component. Said component is preferably a thyristor 16 which lets one mains half-wave pass and turns off as soon as the half-wave changes sign. Thus as soon as an electrical fault is cleared after tripping, turn-on of the control component and consequently flow of a current in the actuator does not last any longer than one subsequent period. The triggering means without storage are for example comparators integrated in the processing circuit 14.
The actuator can thus be connected to a power supply line up-line from the electrical contacts as in figures 2 and 3 or down-line from the electrical contacts.
In a third embodiment of the invention represented in figure 8, the power supply line 7 is located down-line from the contacts 1 on the same side as the sensor 5. In this embodiment, the processing unit 4 comprises a tripping device 19 on a voltage surge. This device comprises a relay 20 of bitable type operating a mechanical indicator. This relay is cormected in series with a second control thyristor, the assembly formed by the relay 20 and thyristor 21 being connected between the first and second outputs of the processing unit, i.e. in parallel on the first thyristor 16. To detect a voltage surge, the thyristor 21 is controlled by a divider bridge comprising resistors 22 and 23 cormected between the anode and cathode of said thyristor, and by a threshold diode 24 connected between the common point of the divider bridge and the thyristor trigger. A filter 25 connected to the trigger of


the thyristor 21 enables disturbances of short duration to be filtered.
In this embodiment, the tripping device 19 is protected by the voltage dependent resistor 8 and the windings 10 and 12 of the actuator.
In the devices described above, the processing unit comprises circuits for tripping on differential current and/or supply voltage surge. The invention can however relate to other tripping or indication functions, such as for example tripping on neutral break or external opening commands or other functions acting on the actuator.
The electrical fault protection devices according to the embodiments of the invention are in particular differential circuit breakers, differential switches, or relays comprising actuators.
The threshold diode is a diode having a voltage threshold such as avalanche diode, breakdown diode, or Sneer diode. When an inverse voltage exceeds the threshold, a current begins to pass through the diode.
The thyristor trigger is the electrode of the thyristor designed to control turn on the component. This command electrode can be named trigger, gate, turn on gate, control electrode, or command electrode. Indeed a thyristor comprises an anode, a cathode, and a control electrode (trigger or gate).


WE CLAIM:
1. A device for protection against electrical faults comprising: measuring means (5) for measuring a fault current, processing means (4) connected to the measuring means, an actuator (3) connected to the processing means and to a power supply line (7) to bring about opening of electrical contacts (1) and limiting means (8) connected to the actuator for limiting voltage surges on said actuator, a device characterized in that the actuator comprises: a first winding (10, 10a, 10b) connected between the power supply line and a common output (11) connected to the limiting means (8) for limiting voltage surges, and a second winding (12) connected between the common output (11) and the processing means (4).
2. The device as claimed in claim 1, wherein the first winding (10) is achieved in two parts (10a, 10b) separated by an insulating shield (13).
3. The device as claimed in any one of the claims 1 or 2, wherein the actuator comprises a movable magnetic core (9) located essentially in the first winding (20, 10a, 10b) when the actuator is in the stationary position.
4. The device as claimed in any one of the claims 1 to 3, wherein the first (10) and second (12) winding have appreciably the same number of turns.
5. The device as claimed in any one of the claims 1 to 4, wherein the first and second winding have a number of turns equal to or less than 700.
6. The device as claimed in any one of the claims 1 to 5, wherein processing means (4) comprise a component (16) which switches to the open position when the current flowing through this component is nil, and triggering means (14) supplying a control signal without retaining a tripping signal after a fault to command the turn-on said component, the actuator being connected to said AC power supply line (7).


a power supply line (7) either upstream line or downstream line from the electrical contacts (1).
8. The device as claimed in any one of the claims 1 to 7, wherein the processing
unit comprises means (14, 5, 16) for tripping on a differential fault current.
9. The device as claimed in any one of the claims 1 to 8, wherein the processing
unit comprises tripping means (19, 20 to 25) for tripping on an excess of the voltage
of the power supply line (7).
10. The device as claimed in claim 9, wherein the tripping means (19, 20 to 25) for
tripping on an excess of the voltage of the power supply line comprise a mechanical
indicator controlled by a relay (20) connected to a winding of the actuator.

Documents:

1112-mas-2000-abstract-duplicate.pdf

1112-mas-2000-abstract.jpg

1112-mas-2000-abstract.pdf

1112-mas-2000-claims-duplicate.pdf

1112-mas-2000-claims.pdf

1112-mas-2000-correspondence-others.pdf

1112-mas-2000-correspondence-po.pdf

1112-mas-2000-description-(complete)-duplicate.pdf

1112-mas-2000-description-(complete).pdf

1112-mas-2000-drawings-duplicate.pdf

1112-mas-2000-drawings.pdf

1112-mas-2000-form-1.pdf

1112-mas-2000-form-19.pdf

1112-mas-2000-form-26.pdf

1112-mas-2000-form-3.pdf

1112-mas-2000-form-5.pdf

1112-mas-2000-others.pdf

1112-mas-2000-petition.pdf


Patent Number 216176
Indian Patent Application Number 1112/MAS/2000
PG Journal Number 13/2008
Publication Date 31-Mar-2008
Grant Date 10-Mar-2008
Date of Filing 21-Dec-2000
Name of Patentee SCHNEIDER ELECTRIC INDUSTRIES SA
Applicant Address 89, BOULEVARD FRANKLIN ROOSEVELT, F-92500 RUEIL MALMAISON,
Inventors:
# Inventor's Name Inventor's Address
1 BLANC PATRICK LA CHAPELLE - 71260 BURGY,
2 FONTANA FRANK 25 GRANDE RUE SAINT-COSME-71100 CHALON SUR SAONE,
3 LEBEAU BERNARD MAIZERAY 71460 SAINT MARTIN DU TARTRE,
4 TIAN SIMON 58 RUE GLORIETTE-71100 CHALON SUR SAONE,
PCT International Classification Number H02H 3/08
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 9916209 1999-12-22 France