Abstract: A vector control system for a squirrel-cage asynchronous motor powered by a width-modulated pulse generator, the system including a device for evaluating the modulus and the phase of at least one of the fluxes in the motor relative to a fixed frame of reference, and a device for evaluating first in-phase and quadrature components, relative to the flux of at least one of the currents supplied to the motor. The system also includes means a device for determining second in-phase and quadrature components relative to the flux in the motor, defining a control voltage as a function at least of the first components and of a requested torque value, together with means a device for converting the second components into a corresponding polar representation having a modulus and an argument, for the purpose of controlling the pulse generator.

Abstract: A high tension circuit breaker having a dielectric gas under pressure, the circuit breaker being of the type including at least one interrupting chamber comprising an insulating shell filled with the gas and containing a fixed assembly including a fixed main contact and a fixed arcing contact, a moving assembly including a moving main contact and a moving arcing contact, a blast cylinder opening out into a blast nozzle, and a pair of secondary contacts, the circuit breaker being characterized in that the blast cylinder is delimited by a first cylinder (5) constituting the moving arcing contact, a second cylinder (7) constituting the main moving contact, and a semi-moving first piston (14) carrying one of the secondary contacts, with the other secondary contact (31) being carried by a fixed tube (15) which, together with the first piston, an insulating tubular extension (5B) of the first cylinder (5), and a second piston fixed to the cylinder (5) and sliding along the fixed tube, delimits a second closed volum

Abstract: A circuit breaker for high and medium tension including insulation by means of a dielectric gas and puffer arc blasting, the circuit breaker comprising a gastight insulating casing, containing:a fixed assembly comprising, in particular, a fixed main contact and a fixed arcing contact;a moving assembly driven by a drive rod and including, in particular, a moving main contact and a moving arcing contact;a first blast volume extended by a blast nozzle;a blast piston; andfirst and second secondary contacts disposed inside a second volume and designed to strike a secondary arc;wherein the first secondary contact is fixed relative to the fixed assembly, the second secondary contact being semi-moving relative to the moving assembly, possessing its own source of energy for displacing it during a circuit breaker disengagement operation, and being provided with means for conferring a shorter stroke thereto than the stroke of the moving assembly.

Abstract: A dielectric blast gas circuit breaker comprising a main fixed contact, a main arcing contact, and moving equipment including, in particular, a moving arcing contact and blast means, wherein the circuit breaker includes a moving main contact which is disunited from the moving equipment and which is implemented by means of a short cylindrical element associated with means communicating a speed thereto during circuit breaking which is lower than the speed of the moving equipment. The invention is applicable to medium tension circuit breakers having a high nominal current, such as the circuit breakers used in a power station.

Abstract: A medium tension circuit breaker having a dielectric blast gas, the circuit breaker comprising a cylindrical insulating casing filled with dielectric gas under pressure, a fixed main contact, a fixed arcing contact, a fixed blast piston, and moving equipment connected to an operating member and comprising a moving main contact, a moving arcing contact, and a blast cylinder associated with a blast nozzle, wherein the circuit breaker includes a drive piston whose section is not less than 1.3 times the section of the blast piston, the drive piston moving relative to a second cylinder.

Abstract: A high- and medium-voltage gas circuit breaker comprises a cylindrical electrically insulative enclosure filled with dielectric gas under pressure, a fixed main contact and a fixed arc contact. A mobile assembly is coupled to an operating member and comprises a mobile main contact, a mobile arc contact and a blow-out cylinder associated with a blow-out nozzle and cooperating with a first piston. A second piston is fastened to the mobile assembly and slides in a fixed second cylinder. The second piston has a large cross-section in relation to the cross-section of the blow-out cylinder. The second piston is associated with a system for providing low head loss communication with the arc area and comprises orifices of calibrated size to limit the pressure on the face of the piston on which the gas heated by the arc impinges.

Abstract: A steam turbine installation with bleeding adjusted to a predetermined pressure P, the installation driving a load and including a bleed outlet disposed between two successive stages, wherein the bleed pressure P is adjusted over a range D of bleed rates by a servo valve disposed on the exhaust duct and controlled by a servo-control circuit including device for measuring the pressure of the bleed flow.

Abstract: The present invention provides a circuit breaker in which the blast cylinder is delimited by a first cylinder (5) constituting the moving arcing contact, a second cylinder (7) constituting the fixed main contact, and a first piston (14) sliding between said first and second cylinders, said first piston being urged by a spring (17) to come into abutment against a part (16A) fixed to the fixed assembly, the cylinder (5) constituting the moving arcing contact and a tube (16) connected to the fixed assembly and coaxial with said cylinder together delimiting, on the other side of the piston (14) closing the blast cylinder, a variable volume (35, 35B) closed at one end by said first piston (14) and at its other end by an annular end piston (42) connected to said first cylinder (5) and sliding along said tube (16), said volume enclosing said secondary contacts, a first secondary contact (30) being fixed to said tube (16) and the second secondary contact (31) being entrained by said first cylinder (5).

Abstract: A circuit for measuring voltages in a three-phase installation, in particular an installation of the metalclad type, the circuit including for each of the phase conductors: a capacitive divider including a first capacitor connected firstly to said conductor and secondly to a second capacitor (C1, C2, C3) connected to ground, the circuit being characterized in that the voltage (v1, v2, v3) of each of the second capacitors (C'1, C'2, C'3) of the dividers is respectively applied firstly to the input of an inverter (I1, I2, I3) and secondly via a first resistance (R1, R2, R3) to the negative input of an operation amplifier (A1, A2, A3) which is also connected via second and third resistances (R21, R12, R13, and R31, R32, R23).

Abstract: The invention relates to a system using Rogowski coils to measure the phase currents in a three-phase installation. Each coil (1, 2, 3) is connected firstly to a corresponding operational amplifier (10, 20, 30) connected as an integrator, and secondly to a corresponding inverter (100, 200, 300) whose output is connected to the inputs of the integrating amplifiers of the other two phases. With appropriately selected resistance values, mutual interference effects may be cancelled. The system is suitable for measuring phase currents in an installation housed in a cabinet or cubicle.