Contactor-circuit breaker housing firstly power poles and an electromagnet serving to activate the moving contacts in contactor mode and including a fixed magnetic circuit, a moving magnetic circuit and a coil whose electric supply is controlled by a switch, and secondly at least one current sensor serving to control a releasing electromagnet. The activating electromagnet and the releasing electromagnet are constituted by a single electromagnet whose moving magnetic circuit is a pivoting pallet linked mechanically to the contact-holders of the poles and having a weak moment of inertia. An electric unit is provided for the rapid reduction of the magnetic flux, triggered by an electronic control device associated with the current sensor.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a contactor-circuit breaker housing firstly power 
poles which include moving contact bridges cooperating with fixed contact 
bridges, and an electromagnet serving to activate the moving contacts in 
contactor mode and comprising a fixed magnetic circuit, a moving magnetic 
circuit and a coil whose electric supply is controlled by a switch, and 
secondly at least one current sensor serving to control a releasing 
electromagnet. 
2. Discussion of the Background 
A contactor is used to cut off or to supply, in response to a control 
signal, the supply line of a load such as a motor. A circuit breaker is 
usually associated with the contactor, the purpose of which circuit 
breaker being to open the line if an overcurrent, due for example to a 
short-circuit, is detected. The circuit-breaker function is necessary in 
order to open the line quickly, for the opening of the contactor for the 
purpose of cutting off the supply to the electromagnet coil would take too 
long because of the slow decline of the current through the coil. 
The contactor and circuit breaker functions are sometimes combined in a 
single electric switch appliance, referred to as contactor-circuit 
breaker, such as the appliance described in French patent FR2638563. A 
protection device, such as for example a striker, is thus associated with 
the contact bridge of the contactor, which device acts directly on the 
moving contact bridge so as to open the contacts in case of detection of a 
short-circuit current. This appliance also comprises a lock which receives 
orders from the (thermal and magnetic) protective device in order to act 
on the supply of the coil. However, such an appliance remains bulky and 
expensive. 
SUMMARY OF THE INVENTION 
This invention therefore aims to provide the necessary control and 
protection functions sought in a contactor-circuit breaker appliance by 
means of the rapid opening of a single moving magnetic circuit acting on 
the contact-holders. This appliance avoids the need for mechanical 
protective devices, is of standard size and of low cost price. 
According to the invention, the switch appliance is characterized in that 
the activating electromagnet and the releasing electromagnet are 
constituted by a single electromagnet whose moving magnetic circuit is a 
pivoting pallet linked mechanically to the contact-holders and having a 
weak moment of inertia, and in that it comprises electric means for the 
rapid reduction of the flux in the magnetic circuits, these means being 
triggered by an electronic control device associated with the current 
sensor. 
According to an embodiment of the invention, the electric means include a 
rapid-opening electronic switch which is positioned in series with the 
coil, and an electric component or system for the rapid reduction of the 
current which is placed in parallel with the terminals of the 
rapid-opening switch so as to be in series with the coil in order to form 
a closed current loop when the switch is placed in the off state by the 
control device. Upon opening of the switch, the electric means allow the 
current in the coil, and consequently the flux in the magnetic circuits, 
to fall rapidly without altering the normal functioning of the appliance. 
The electric component is preferentially constituted by a Zener diode with 
a controlled avalanche voltage which is less than the breakdown voltage of 
the rapid-opening switch. 
In a particular embodiment of the invention, the electric means include the 
coil supply control switch and a rapid current-reduction electric 
component which is placed in parallel with the terminals of the coil so as 
to be in series with the coil when the control switch is placed in the off 
state by the control device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The electric switch appliance illustrated in FIG. 1 is a contactor-circuit 
breaker which is designed to cut off or establish the passage of the 
current in the supply line of a load such as an electric motor. It 
incorporates the circuit-breaker function so as to be able to open the 
line rapidly in response to the detection of a fault current. 
The appliance includes several power poles housed in a casing body 1, which 
poles each comprise a moving contact bridge 2 cooperating with fixed 
contacts 3, 4 which are carried respectively by conductors 5, 6. Each 
contact bridge 2 is mounted on a translationally guided contact-holder 7. 
An electromagnet 10 is housed in the casing 1 in order to control the 
opening and closing of the power poles. The electromagnet 10 comprises a 
fixed magnetic circuit 11, a coil 12 with at least one winding L and a 
moving magnetic circuit 13 designed to be attracted, in the closed 
position, by the fixed magnetic circuit when the coil 12 is supplied in 
current and attracted towards an open position by at least one spring R. 
The moving magnetic circuit 13 is a pivoting pallet articulated around an 
axis 14 and linked mechanically to the contact-holders 7 by means of an 
articulated mechanical liaison 8. 
Since the currents induced are limited by the nature of the high 
resistivity material, the shape and the technology of the moving magnetic 
circuit, it is assumed for the purposes of this invention that the current 
variation in the coil is equivalent to the magnetic flux variation. 
The coil 12 is supplied in direct current or in rectified alternating 
current by a diode bridge (FIG. 2). The coil 12 positioned on a principal 
current path C1 between two supply lines, an outward line a connected to 
the terminal B1 of the coil and a return line b connected to the terminal 
B2. 
The coil 12 supply is controlled by a switch 20 placed on the current path 
C1. The switch 20 is of mechanical type but may also be a semi-conductor, 
for example of IGBT or MOS bipolar type. Switch 20 may be associated with 
a current chopper device in order to regulate the current in the coil 
during normal functioning of the contactor. The switch 20 may be 
controlled by an electronic control device 40, and may be activated in the 
event of detection of an overload fault. 
A freewheeling diode 21 is positioned on a derived current path C2 so as to 
be in series with the coil when the switch 20 is in the off state, its 
cathode and anode being linked respectively to the line a and the terminal 
B2 of the coil 12. This diode 21 ensures electric continuity during normal 
functioning of the contactor when the switch 20 is in the off state. 
The appliance includes electric means 30 for the rapid reduction of the 
magnetic flux through the rapid decline of the current in the coil 12 of 
the electromagnet. These means are implemented by the electronic control 
device 40 in the event of detection, by at least one current sensor 50, of 
a short-circuit fault on the supply line of the load circuit. A current 
sensor 50 is placed on each current line. 
The electric means 30 for the rapid reduction of the flux include a 
rapid-opening electronic switch 31 and a rapid current reduction electric 
component or system 32. 
The rapid reduction of the current in the coil, and thus the rapid 
reduction of the magnetic flux, depend on the electrical characteristics 
of the component 32 and the coil 12. 
The Switch 31 is placed on the principal path C1 in series with the coil 12 
and the switch 20. Switch 31 is designed to be in the off state in the 
event of detection of a short-circuit. Switch 31 switching is controlled 
by the control device 40 which is capable of receiving and treating a 
short-circuit fault detection signal supplied by the sensor 50. In this 
case, supply to the coil is cut off by opening of the switch 31, 
irrespective of the state of the switch 20. 
The electric component 32 is mounted in parallel with the terminals of the 
switch 31 so as to be in series with the coil 12 and the diode 21 when the 
said switch 31 is in the off state in order to constitute a closed current 
circuit. 
The component 32 is preferentially constituted by a Zener diode, its 
cathode and anode being respectively connected to the line a and the 
terminal BE of the coil. 
The switch 31 and the component 32 may equally be placed upstream or 
downstream of the coil 12, while being upstream of the switch 20. 
In a non-illustrated variant of the invention, the electric component or 
system 32 may be an RLC-type oscillator circuit which is positioned in 
parallel with the terminals of the coil 12. 
Finally, the freewheeling diode 21 ensures electrical continuity when the 
switch 31 moves to the off state. When the coil is supplied in rectified 
alternating current and the switch 20 is in the on state, electrical 
continuity may be ensured by the diode bridge instead of the diode 21. 
FIG. 3 illustrates the diagram of FIG. 2 for a coil 12 fitted with two 
windings L1 and L2 placed in parallel. The winding L1 constitutes the call 
winding causing the moving magnetic circuit of the electromagnet to move, 
while the winding L2 constitutes the maintaining winding which keeps the 
moving magnetic circuit in the attracted position. Switches 20a and 20b 
respectively control the supply of each winding. A freewheeling diode 21 
and electric means 30 for the rapid reduction of the magnetic flow are 
associated with each winding L1 and L2. 
In the event of detection of a short-circuit fault during the call phase, 
the two switches 31 associated with the windings L1 and L2 are opened 
simultaneously. In the event of detection of a short-circuit fault during 
the maintaining phase, only the switch 31 associated with the winding L2 
is opened since the winding L1 is no longer supplied. 
In a non-illustrated variant of FIG. 3, the switch 20a and the diode 21 
associated with the call winding L1 are eliminated. The call-maintaining 
commutation is here carried out by the switch 31 of the means 30 
associated with the call winding L1, and electrical continuity is ensured 
by the freewheeling diode 21 associated with the maintaining winding L2. 
In a variant of FIG. 2, as illustrated in FIG. 4, the coil 12 is 
constituted by a transformer T comprising a primary winding L3 and a 
secondary winding L4, the primary winding being placed in series with the 
switch 20. A diode 22 is placed in series with the secondary winding L4. 
The means 30 for the rapid reduction of the flux include the rapid-opening 
switch 31 which is placed in series with the primary winding L3 and the 
electric component 32 which is constituted by a Zener diode and is placed 
in series with the secondary winding L4. 
A description of the functioning of the appliance according to the 
invention will now be given with reference to FIG. 2. 
In normal functioning of the contactor-circuit breaker, the supply of the 
coil is controlled by the switch 20, the switch 31 being in the on state. 
The current, and consequently the magnetic flux, follows a usual decline 
curve according to the electrical characteristics of the coil. 
In the event of detection of a short-circuit, the sensor 50 sends a signal 
to the control device 40 which triggers the change of state of the switch 
31 and blocks it. Owing to the value of the controlled avalanche voltage 
Vz of the Zener diode 32 which is much greater than the supply voltage, no 
current can pass from the supply line a to the line b. 
The flux stored in the magnetic circuits maintains a current in the coil 
which then passes by the diode 21 and the Zener diode 32 by forming a 
closed loop. In passing by the Zener diode 32, the potential at the 
terminals of the coil becomes equal to the controlled avalanche voltage Vz 
and the magnetic flux declines according to the equation Vz/N, where N is 
the number of turns of the coil winding. The voltage Vz is never greater 
than the breakdown voltage V.sub.BR of the switch 31. 
With reference to the circuit shown in FIG. 4, in normal functioning the 
current circulating through the primary winding L3 of the line a towards 
the line b induces a current circulating in the opposite direction in the 
secondary winding L4 which, however, remains blocked due to the presence 
of the diode 22. If the switch 31 is opened following the detection of a 
short-circuit, the current passing through the primary binding L3 then 
circulates in the reverse direction thereby inducing a current in the 
opposite direction in the secondary winding L4 which consequently 
circulates and passes by the Zener diode. The magnetic flux then declines 
according to the equation Vz/N4, where N4 is the number of turns in the 
secondary winding L4. 
The curves 5a and 5b in FIG. 5 show respectively the results of a usual 
flux decline without using the Zener diode and a flux decline using the 
Zener diode. The rapid reduction of the flux down to a value which is less 
than the maintaining flux .PHI.m for which the moving magnetic circuit is 
no longer attracted, thus takes place in a time of less than 3 ms compared 
to a time of approximately 20 ms in normal functioning of the contactor. 
The gap between the times of 1 ms and 3 ms is due to the mechanical 
inertia of the pallet which is nevertheless weak. 
According to the invention, the circuit-breaker function of the 
contactor-circuit breaker is thus carried out firstly thanks to the rapid 
decline of the magnetic flux due to the presence of the electric means 30, 
and secondly by the special arrangement of the electromagnet whose pallet 
13 possesses a weak inertia in order to ensure its rapid movement and 
which constitutes a direct organ for activating the contact-holders 7. 
In a particular embodiment of the invention illustrated in FIG. 6, the 
electric means 30 for the rapid reduction of the flux include the coil 
supply control switch 31 as a rapid-opening switch. In this case, the 
electromagnet is always opened rapidly. According to the diagram, the 
Zener diode 32 is in parallel with the terminals of the coil 12. A diode 
23 is placed in series with the Zener diode 32 in order to block the 
passage of the current coming from the line a only when the voltage Vz is 
less than the maximum supply voltage. When the switch 20 is controlled so 
as to no longer be in the on state (in contactor function or in 
circuit-breaker function), the coil 12 and the Zener diode 32 form a 
closed current loop ensuring the rapid reduction of the current in the 
coil and thus of the magnetic flux.