US1563688A - Electric-circuit breaker - Google Patents

Description

Dec. 1, 1925- 1,563,688

P. CHARPENTIER ELECTRIC CIRCUIT BREAKER Filed April 1'7. 1924 2 Sheets-Sheet 1- Dec. 1 1925. 1,563,688

P. CHARPENTIER ELECTRIC CIRCUIT BREAKER Filed April 17. 1924 2 Sheets-Sheet. 2

e'owamm,

Patented Dec. 1, 1925.

UTNHTEDT STATES PATENT orrics.

PAUL CHARPENTIEB7 QE PARIS, FRANCE, ASSIGNOB T0 FORGES & ATELIERS DE CONSTRUCTIONS ELECTRIQUES DIE JE'UI'IIONT, SOCIETE ANONYME, OF PARIS,

FRANCE.

Application filed April 17, 1924.

To all whom it may concern:

Be it known that I, PAUL GHAnrEN'rInn, a French citizen, and residing at 75 Boulevard Haussmann, Paris, France, have inventedcertain new and useful Improvements in Electric-Circuit Breakers, of which the following'is a specification.

This invention relates to an electric circuit breaker, the opening of which is produced in a very short time and very soon after the moment when the current in the circuit to be protected attains a given value.

The improved circuit breaker comprises essentially an electromagnet having its winding connected in series in the circuit to be protected and with its pole-pieces arranged to attract two movable armatures; one armature which is of small sectional area acts upon the lever carrying the movable contact of the circuit breaker so as to tend to close the contacts, and the other armature, which is of larger sectional area acts upon this same lever in a direction to open the said contacts.

Oneof the characteristic features of the invention resides in the fact that the action of the small section armature is rendered preponderant for the lowest values of the current in the circuit, whilst for a given excess of current the action of the largesection armature becomes preponderant; this result is obtained by the judicious combination and suitable proportioning of the electromagnet, its pole-pieces and its two armatures.

The improved circuit breaker comprises moreover electromagnetic means adapted to reduce quickly the effect of the small-section armatures in case of rapid increase of the current, such as takes place in a short circuit.

Upon the accompanying drawing, to which reference is made in the description given hereinafter Figure 1 represents diagrammatically a form of construction in accordance with the invention.

Figures 2 and 3 are modifications com-.

ELECTRIC-CIRCUIT BREAKER.

Serial No. 707,101.

Figure 4 represents by way of example a modification of the mechanism actuating the contact-lever by the two movable armatures.

Figure 5 represents a further modification, constituting the preferred construction.

In all these figures the same reference letters designate the same parts. i

The circuit breaker represented in Figure 1 comprises a stationary contact a and a movable contact 6. The latter contact is secured to a lever c pivoted at 0 upon a bellcrank lever h 72/ itself pivotally mounted upon a stationary spindle 0 the said lever c is connected by a flexible lead (Z to the series excitation winding 6 of the laminated electromagnet On one of the faces of the pole-pieces of the electromagnet f there is located a laminated iron armature g of small sectional area and upon the other face of the said pole-pieces there is arranged a large-section armature 72,; these two armatures are coupled together, the small-section armature 9 being fixed directly upon the lever c and the large-section armature it being fixed upon the bell crank lever h, 7%.

It will be understood that the connection between the armatures and the lever can be effected by means of any suitable device,in particular by any system of jointed links for ensuring the transmission of the motion of the armature to the lever.

When the circuit breaker is in the closed position, the parts a b are in contact and the small-section armaturev g is itself in con.- tact with the pole-pieces of the electromagnet 7', while an air gap exists between the large-section armature h and the said pole pieces. 7

If the current in the circuit increases, the ampere-turns will increase in the series winding 6 of the electromagnet fiand the magnetic flux passing through the armatures g and It will increase likewise. But by reason of the rapid saturation of the small-section armature g, the magnetic flux passing through it will then increase very slowly as also the attraction exerted upon this armature g by the electro-magnet f; on the other hand, the flux traversing the large-section armature it will increase aliost in the same proportions. as the current and therefore the attraction exerted by the electromagnet f upon this armature it will increase approximately as the square of this current.

The device is so arranged that when a given value of the current is reached, the attraction exerted upon the large-section armature it assumes the preponderance. At this moment the armature h is drawn to the pole-pieces of the electromagnet f and the previous contact between these pole-pieces and the small-section armature g ceases. The lever 0 actuated by the movement of the armature h is pushed back towards the left until its lower end abuts against an adjustable stop 8. This movement causes the contact a to assume an inclined position in relation to the contact Z), before the actual separation of these contacts; the break can therefore take place only at their upper edge. This separation is then effected by the action of the armature h continuing its movement while the lever 0 bears against the stop 8.

During this operation the air gap of the small-section armature 9 increases relatively quickly and the influence of this armature diminishes very rapidly, whereas the action of the larger armature it will increase progressively as its air gap constantly decreases; in these conditions the displacement of the lever c is accelerated rapidly from the very start of the releasing movement.

The lever 0 is provided with a hook p which during the release comes into engagement with a spring catch 9 at the end of the stroke of the said lever 0. Moreover the device can be arranged in such a way that the centre of gravity of the movable system 0 g h h, 72 at the end of the stroke of the lever 0 remains on the right of the vertical line passing through the axis of rotation 0 In order once more to close the circuit breaker it is only necessary to actuate the catch ,9 either directly or by means of an electromagnet controlled from a distance, so as to free the hook 29. The lever 0 will then fall by its own weight into the closed position; while the armature It moves away from the pole-pieces, the armature 9 will approach these poles on the other face.

As soon as the contacts a b touch one another, the current in the circuit will energize the electromagnet f; the small section armature 9 will be attracted and will cause a sliding movement of the contact it over the contact a in such a way as to maintain the contact surfaces always in good condition.

The method of construction represented in Figure l of the drawing might be modified, without affecting the result obtained, by arranging the links between the armatures g h and the lever 0 in such a way as to bring the point of application of the force exerted by the larger armature below the point of application of the force exerted by the small armature upon the lever 0.

Also as shown in Figure 4 of the drawing, the small-section armature 9 might be secured rigidly to the lever 0 at 9,; in this case the armature it would be fixed upon a bell crank lever h h pivoted on the lever c at a point 7L4 situated below the fixing point g,. The lever k would then pivot always around a fixed axis 0 This arrangement has for effect to increase the pressure between the contacts a b when the current in the circuit rises, and it constitutes a special feature of the invention eminently suited to ensure the preservation of the contacts and to prevent them becoming overheated.

In the same way, it may be desirable to shunt the series winding 6 of the electromagnet by a parallel circuit of higher self induction and lower resistance, in such a way as to obtain the release of the circuit breaker for a lower value of the total current in the circuit in the case of a sudden short circuit than in the case of a slowly increasing overload.

This last condition may also be fulfilled more eificaciously and more economically by providing the small-section armature g with a single coil or a winding forming a shortcircuit, as indicated in Figure 2 of the drawing. The short-circuit coil 11 has naturally no action in the case of a slow increase of the overload, but in the case of a sudden short-circuit the variation of flux in the small-section armature g is retarded by the current induced in the auxiliary winding '5, whether the flux in the armature 5/ be already near to the saturation point as would be the case for a short-circuit occurring at full load, or whether this flux be still very weak, as would happen in the case of a short-circuit already existing at the time the circuit is closed. In such case the action of thelarge-section armature h will then become preponderating for a value of the total current in the circuit lower than that which would be necessary in the case of a sudden short-circuit, if the short-circuit winding 2' did not exist; this effect will be still more accentuated if there happens to be a short-circuit at the moment when the circuit is closed. In the modification represented in Figure 3 of the drawing, the release for a lower value of the total current in the case of a sudden short-circuit than in the case of a slow increase of the overload, is obtained by arranging upon the smallsection armature g a winding j in parallel to the series winding 0 which energizes the electromagnet This winding is of comparatively fine meaeee wire and its resistance is much greater than that of the winding 6, so that in case of a slow increase of the load its ampereturns only affect very slightly the magnetization of the small armature g.

The direction of the winding is more over selected in such a way that the magnetic flux which it produces in the smallsection armature 9 will be of opposite sense to the flux generated in this armature by the series winding 0.. The self; induction of. the shunt coil being then lower than that of the winding 6, it follows that in the case of a sudden short-circuit the portion of the total current shunted into the winding 7' is much greater than in the case of a slowly increasing overload.

In these conditions, when a sudden shortcircuit occurs, the ampere-turns of the shunt coil j acting in the opposite direction to the flux produced in the small armature g by the winding 6, will have for effect to reduce the force of the attraction of this armature and to render the attraction of the larger armature A much more rapidly preponderant.

It may be remarked that in the case when a short-circuit exists at the moment when the circuit is closed, and when consequently no current yet exists in the winding 6 at the moment when the short-circuit first takes alace, the flux due to the coil j would at iirst exist alone in the small armature g; but the winding having a high resistance the current passing through it is at each instant only a very small fraction of the total current in the circuit. The remainder of the current circulates through the winding 6 and the flux due to this winding in the armature i although increasing more slowly will nevertheless obtain very rapidly a value equal to that produced by the shunt coil 7'. At this moment the force of attraction of the larger armature h existing alone will produce the release of the circuit breaker.

Naturally the releasing effort for the circuit breaker device can be reinforced by the action of a spring 76 acting upon the lever as shown in Figure 3 of the drawing. In this case the re-engagement will require the use of a lever or eleetromagnet sufficient to overcome the force of this spring is.

The re-engagement which took place under the action of gravity in the example of construction previously described with reference to Figure 1, can be produced by the action of a spring Z adapted to return the lever c to the closed position after the release of the hook p, as shown for example in Figure 4: of the drawing.

Figure 5 represents the )referred arrangement for carrying out t e invention. In this case the two armatures g h are connected to the lever 0 by independent means at g, and h, respectively, as in Figure 4, and the smaller armature g is provided with a shunt coil j, similar to that shown in Figure 3. Thus the attraction of the two armatures towards the magnet produces'a torque upon the lever c in a direction tending to increase the pressure between the contacts a b as the current in the coil 0 increases. At the same time the shunt coil 7' producing an independent flux in the armature g, controls the circuit breaker as previously described in the event of a sudden short circuit.

Having thus described my invention, what I claim is 1. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact co-operating with said mov able contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, means controlling said armatures to produce opposite movements in relation to said magnet, mechanical connections between said lever and one of said armatures, and means for limiting the movement of said lever at a point remote from said movable contact, said limiting means forming a fulcrum for further movement of said lever to produce rapid separation of said con tacts.

2. A. circuit-breal'rer, comprising a lever, a movable contact carried by said lever, a fixed contact co-operating with said movable contact, an electromagnet, a series winding energizing said magnet, oppositely directed pairs of pole-pieces upon said magnet, two armatures of different size attracted. by said pairs of pole-pieces respectively, meanscontrolling said armatures to produce opposite movements in relation to said magnet, mechanical connections between said lever and one of said armatures, and a stop for the extremity of said lever remote from said movable contact, said step forming a fulcrum for pivotal movement of said lever to produce rapid separation of said contacts.

3. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact co-operating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, a bell crank lever secured tOztllG larger of said armatures, and a pivot supporting one extremity of said bell crank, the otherentremity of said bell crank attached to said contact-carrying lever, the other of said armatures also attached to said contact-carrying lever.

4. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact co-operating with said movable contact, an electromagnet, a series win d;-

ing energizing saidmagnet, two armatures of different sectional area attracted by said magnet, means controlling said armatures to produce opposite motions in relation to said maget, mechanical connections between said lever and one of said armatures, and an auxiliary coil surrounding one of said armatures, said auxiliary coil having a very small number of turns.

5. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different sectional area attracted by said magnet, means controlling said armatures to produce opposite motions in relation to said magnet, mechanical connections between said lever and one of said armatures, and a shunt-coil producing an independent mag netic flux in one of said armatures, said shunt-coil being connected in parallel to said series winding.

6. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different sectional area attracted by said magnet, means controlling said armatures to produce opposite motions in relation to said magnet, mechanical connections between said lever and one of said armatures, and a shunt-coil producing an independent magnetic flux in one of said armatures, said shunt-coil being of lower self induction and higher resistance than said series winding.

7. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, a bell crank lever secured to the larger of said armatures, a pivot supporting one extremity of said bell crank, the other extremity of said bell crank attached to said contact-carrying lever, the other of said armatures also attached to said contactcarrying lever, and a spring acting upon said lever in a direction to close said contacts.

8. A circuit-breaker, comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures attracted by said magnet, one of said armatures being of smaller sectional area so as to approach magnetic saturation at a given value of the current, the other armature being of larger sectional area so as to provide a magnetic flux approximately proportional to the current even beyond said value, means controlling said armatures to produce opposite movements in relation to said magnet, and mechanical connections between said lever and one of said armatures.

9. A circuit-breaker,comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, means controlling said armatures to produce opposite movements in relation to said magnet, independent mechanical connections becontact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, means controlling said armatures to produce opposite movements in relation to said magnet, independent mechanical connections between said lever and said two armatures respectively, said independent mechanical connections acting upon said lever to produce torque in a direction tending to increase the pressure between said contacts, and a stop for the extremity of said lever remote from said movable contact, said stop forming a fulcrum for the further move ment of said lever to produce rapid separation of said contacts.

ll. A circuit breaker, comprising a lever, a movable contact carried by said lever, a

fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, means controlling said armatures to produce opposite movements in relation to said magnet, mechanical connections between said lever and one of said armatures, means for increasing the pressure at said contacts as the current increases to a given maximum value, and means for producing a rapid movement of said lever to separate said contacts when the given maximum Value of the current is exceeded.

12. A circuit breaker, comprising a lever, a movable contact carried by said lever, a fixed contact cooperating with said movable contact, an electromagnet, a series winding energizing said magnet, two armatures of different size attracted by said magnet, means controlling said armatures to produce opposite movements in relation to said magnet, mechanical connections between said said lever and of the smaller of said armalever and said armatures, said mechanical tures to produce rapid separation of said. connections permitting movement of said contacts. 10 armatures independently of one another, In testimony whereof I hereunto afiix my and a stop for the extremity of said lever signature.

remote from said movable contact, said stop forming a fulcrum for pivotal movement of PAUL CHARPENTIER.

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