FR2793030A1 - Device, having a measuring shunt, for pre-paid electrical energy supply control - Google Patents

Abstract

The device has: - terminals (2 to 5) connected to the phase (P) and neutral (N) of an electrical supply network; - an electrical shunt (6) having first and second longitudinal ends arranged in series with a contact (7) of a relay, between measuring terminals (10,11) of the measuring zone (12), the shunt voltage represents the current (I) circulating in the phase conductor (P; - a processor (9), see Fig.1, connected to the terminals (10,11), calculates the energy consumed and control opening of the contact (7) of the relay when the consumed energy value reaches the pre-paid set value. The processor (9) includes a printed circuit card (24). The shunt (6) comprises a plate of electrically conducting material having a longitudinal axis (A) arranged parallel to the printed circuit card (24). The measuring zone (12) is arranged in a plane perpendicular to the printed circuit card (24). the measuring terminals (10,11) of the shunt part through the shunt in the measuring zone (12) on the same side as the longitudinal axis (A) and are soldered directly onto the printed circuit card (24).

Description

4f 2793030

  PREPAYMENT ENERGY MONITORING DEVICE COMPRISING A

MEASURING SHUNT

  The invention relates to a prepaid energy control device comprising terminals for connection to phase and neutral conductors of an electrical network, an electrical shunt having first and second longitudinal ends, arranged in series with a contact. a relay, between the terminals for connection to the phase conductor and supplying, between two measurement terminals delimiting on the shunt a measurement area, a voltage representative of the current flowing in the phase conductor, a processing assembly connected to the terminals measurement, calculating the amount of energy consumed and controlling the opening of the relay contact when said amount of energy reaches a predetermined prepaid value, the processing assembly comprising at least one

printed circuit board.

  It has already been proposed to use a shunt for current measurement in a prepayment energy control device. Known shunts are made of a resistive material soldered to copper plates connected by braids to connection terminals of the conductor in which the current is to be measured. Measurement terminals are connected

  by twisted wires to the measurement inputs of a processing circuit.

  The object of the invention is a prepayment energy control device with a shunt of

  measurement, the cost of which is reduced while improving the reliability of the measurement.

  According to the invention this object is achieved by the fact that the shunt consists of a plate of electrically conductive material having a longitudinal axis disposed substantially parallel to the printed circuit board, the measurement area being arranged in a plane substantially perpendicular to the printed circuit board, the measurement terminals of the shunt projecting towards the outside of the shunt, in the plane of the measurement area, on the same side

  of the longitudinal axis and being soldered directly to the printed circuit board.

  According to a development of the invention, the first longitudinal end of the shunt constitutes a connection area to one of the connection terminals to the conductor of

  phase, the second longitudinal end of the shunt being connected to the relay contact.

  Other advantages and characteristics will emerge more clearly from the description which follows of particular embodiments of the invention, given by way of nonlimiting examples, and represented in the appended drawings in which

  FIG. 1 illustrates, in the form of a block diagram, a device according to the invention.

  FIG. 2 represents a particular embodiment of a device according to the invention,

in front view, without cover.

  Figure 3 shows in more detail a particular embodiment of a shunt and its

  positioning in a device according to the invention.

  Figures 4 and 5 show, in profile view, two alternative embodiments of a shunt

of a device according to the invention.

  The prepayment energy control device 1 shown in FIGS. 1 and 3 is connected by two connection terminals 2 and 3 to a P phase conductor of an electrical network. It is also connected by two connection terminals 4 and 5 to a

network neutral conductor N.

  An electrical shunt 6 is connected in series with a contact 7 of a relay between the connection terminals 2 and 3. The contact 7 is controlled by an electromagnet, or coil 8 of the relay. An electrical processing unit 9 is connected to terminals 2 and 4, so as to receive signals representative of the voltage U between the phase P and neutral conductors N. It is also connected to two measurement terminals 10 and 11 of the shunt delimiting a measurement area on the shunt 12. The voltage present between the measurement terminals 10 and 11 is representative of the current I flowing in the phase conductor P. The voltage U is also applied to inputs of a supply circuit 13 who

  supplies the device with an appropriate supply voltage Vcc.

  The electronic processing assembly 9 comprises a processing circuit 14, preferably with a microprocessor, powered by the voltage Vcc and receiving the signals U and I. The processing circuit 14 calculates, in a conventional manner, the amount of energy consumed by a user connected to the network. It is also connected to a card reader 15, of the conventional type. An electronic card 16 can be inserted into an input slot 17 of the card reader. In a preferred embodiment, the electronic card 16 is a memory card, of the disposable type, in which the amount of a predetermined energy credit, for example 100 kWh, is stored. The amount of this credit is read by the card reader after insertion of the card 16 into the slot 17. The processing circuit 14 causes, through the coil 8 of the relay, the opening of the contact 7 and the interruption of energy supply to the user when the entire energy credit

has been consumed.

  The shunt 6 consists of a plate of electrically conductive material manufactured by

  cutting a piece of electrically conductive material, preferably constantan.

  The shunt 6 has a longitudinal axis A. In FIGS. 2 and 3, a first longitudinal end 18 of the shunt 6 constitutes a connection area to the connection terminal 2. In the particular embodiment shown in FIG. 3, the shunt 6 has a generally substantially rectangular general shape and its first and second longitudinal ends 18 and 19 are slightly narrowed to form shoulders 20 intended to cooperate with elements 21 for positioning and holding the shunt secured to the housing 22 of the device. A braid 23, one end of which is welded to the second longitudinal end 19 of the shunt, connects the shunt 6 to the contact 7 of the relay. In Figure 2, the other end of the braid

  23 is welded to the movable contact element of contact 7.

  The measurement terminals 10 and 11 of the shunt project towards the outside of the shunt, in the plane of the measurement zone 12, on the same side of the longitudinal axis A. The electronic processing assembly comprises at least one printed circuit board 24 on which the shunt 6 is mounted. It is soldered directly to the printed circuit board 24 via its measurement terminals 10 and 11. The longitudinal axis A of the shunt is substantially parallel to the printed circuit board 24. The shunt 6, and more particularly the measurement area 12, are

  arranged in a plane substantially perpendicular to the printed circuit board 24.

  In the variant embodiment shown in FIG. 4, the measurement zone 12 and the ends 18 and 19 are in the same plane. In the preferred embodiment shown in FIG. 5, the ends 18 and 19 have been folded back, forming with the measurement zone 12 an angle greater than 90. The ends 18 and 19 are preferably arranged in substantially parallel planes. This alternative embodiment makes the best use of the internal volume available inside the housing 22. In all cases, it is essential to guarantee good accuracy of the current measurement, that the area of

  measurement 12, located between measurement terminals 10 and 11, as linear as possible, i.e.

say arranged in one plane.

  In the particular embodiment of the shunt shown in FIGS. 1 and 3, the shunt 6 has an additional terminal 25. This is parallel to the measurement terminals 10 and 11, also soldered directly to the printed circuit board 24. This terminal additional of the shunt is arranged between the measurement zone 12 and the longitudinal end 18 of the shunt constituting the connection area to the connection terminal 2. It constitutes the point

  for measuring the voltage of the conductor P and an input to the supply circuit 13.

  Soldering the shunt 6 directly on the printed circuit board 24 improves the reliability of the current measurement made using the shunt. In addition, this is achieved without the power passing through the printed circuit, the entire current passing through the shunt 6 parallel to the longitudinal axis A. To avoid excessive heating of the printed circuit, a minimum distance d (Figure 3) is provided between the printed circuit and the part of the shunt in which the power passes. This can, for example, be achieved by narrowing the end of the measurement terminals 10, 11 and 25, only the end

  narrowed being introduced into the corresponding holes of the printed circuit board.

  The shunt according to the invention makes it possible to minimize the number of parts and connections. Indeed, it makes it possible to remove a connection pad, a braid and wires for connection to the printed circuit. The reduction in the number of parts makes it possible to reduce the cost of the device, while improving the reliability of the measurement. The precision of the positioning of the shunt 6 on the printed circuit board, as well as its positioning and its maintenance in the housing 22, makes it possible not to transmit, at the welds of the shunt on the printed circuit board, the tightening torque of the connection cables, external, nor efforts

  tension that can be exerted on these cables.

Claims (10)

  1.- Prepaid energy control device comprising terminals (2 to 5) for connection to phase (P) and neutral (N) conductors of an electrical network, an electrical shunt (6) comprising first and second longitudinal ends, arranged in series with a contact (7) of a relay, between the connection terminals (2,3) to the phase conductor (P) and supplying, between two measurement terminals (10, 11) delimiting on the shunt a measurement area (12), a voltage representative of the current (I) flowing in the phase conductor (P), a processing assembly (9) connected to the measurement terminals (10, 11), calculating the quantity of energy consumed and controlling the opening of the contact (7) of the relay when said quantity of energy reaches a predetermined prepaid value, the processing assembly (9) comprising at least one printed circuit board (24), device characterized in that the shunt (6) consists of a material plate u electrically conductive comprising a longitudinal axis (A) disposed substantially parallel to the printed circuit board (24), the measurement area (12) being arranged in a plane substantially perpendicular to the printed circuit board, the measurement terminals (10 , 11) of the shunt projecting towards the outside of the shunt, in the plane of the measurement zone (12), on the same side of the axis   longitudinal (A) and being soldered directly to the printed circuit board (24).   2.- Device according to claim 1, characterized in that the first longitudinal end (18) of the shunt (16) constitutes a connection area to one of the connection terminals (2) to the phase conductor (P), the second end   longitudinal (19) of the shunt (6) being connected to the contact (7) of the relay.   3.- Device according to one of claims 1 and 2, characterized in that the shunt (6) is   manufactured by cutting a piece of electrically conductive material.   4.- Device according to any one of claims 1 to 3, characterized in that the   second longitudinal end (19) of the shunt (6) is connected to the contact (7) by   through a braid (23) welded to said end (19).   5.- Device according to any one of claims 1 to 4, characterized in that the   measurement zone (12) of the shunt (6) forms an angle, greater than 90, with each of the   longitudinal ends (18,19) of the shunt.   6.- Device according to claim 5, characterized in that said ends (18,19) are substantially parallel.   7.- Device according to any one of claims 1 to 6, characterized in that it   comprises a housing (22) comprising elements (21) for positioning and maintenance of the shunt (6).   8.- Device according to claim 6, characterized in that it comprises at least one element (21) for positioning and holding constituting a housing of the second   longitudinal end (19) of the shunt, which is connected to the contact (7).   9.- Device according to one of claims 7 and 8, characterized in that the first   longitudinal end (18) of the shunt has shoulders (20) intended to cooperate with elements (21) for positioning and holding the shunt together of the housing (22).   10.- Device according to any one of claims 1 to 9, characterized in that the shunt (6) has an additional terminal (25) soldered directly on the printed circuit board and disposed between the measurement area (12) and the first longitudinal end (18) of the shunt, this constituting a connection area to one of the   connection terminals (2) to the phase conductor (P).