US1191146A - Circuit-breaker. - Google Patents

Description

H. S. BEAKES.

CIRCUIT BREAKER.

APPLICATION FILED OCT-23I 1913. 1,191,146. 1 Patented Jul ls, 1916.

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CIRCUIT BREAKER.

APPLICATION FILED OCT-23. I913.

Patented July 18, 1916.

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HOWARD S. BEAKES, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

CIRCUIT-BREAKER.

Application filed October 23, 1913.

To It whom it may concern.

Be it known that I, HOWARD S. BEAKES, a citizen of the United States, residing at NVilkinsbur-g, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Circuit-Breakers, of which the following is a specification.

My invention relates to circuit breakers of the overload type, and particularly to breakers of this type which are operated to open a circuit by a prolonged current above a given value but which are not operated to open the circuit by a momentary surge of current above the given value or by a current of brief duration above the given value.

One object of my invenion is the provision of a circuit breaker of this type in which the operation by momentary surges of current or by current of brief duration above the given value is prevented solely by'electric or electromagnetic means, thus avoiding the necessity for mechanical or pneumatic means for accomplishing this purpose.

I will describe several forms of circuit breakers embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a view showing in side elevation a circuit breaker of the magnet-and-armature type and including one form of means embodying my invention for preventing operation by momentary surges. Fig. 2 is a view similar to Fig. 1 but showing another form of means embodying my invention for preventing operation by momentary surges or by current of brief duration above the given value. Fig. 3 is a view similar to Fig. 2 but showing a modification of the means shown therein for preventing opera tion by momentary surges or by current of brief duration above the given value. Fig. 4: is a view showing a circuit breaker of the solenoid and plunger type including one form of means embodying my invention for preventing operation by momentary surges.

Similar reference'characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference character 1 designates a U-shaped yoke of magnetizable material, usually soft iron, to the inside faces of the legs of which are secured two magnet cores 2 and 3 respec- Specification of Letters Patent.

Patented July 18, 1916.

Serial No. 796,834.

tively, also of magnetizable material usually soft iron. An armature a of magnet izable material, usually soft iron, is pivoted to the yoke about midway between the two legs as shown, and is adapted to move between pole-pieces 2 and 5 on the ends of the two magnet coresQ and 3. This armature is prevented from actual contact with either pole-piece by short core pins 5 and 6 of non-magnetizable material to prevent sticking due to residual magnetism. Pole-piece 3 is preferably shaped somewhat as shown, so that when the armature lies against this pole-piece the air gap between the two will have low reluctance. The armature is biased by suitable means, as here shown by gravity, to the position shown in the drawing, that is, to engagement with core pin 5 of core 3.

Core 2 is provided with a winding 7 which forms part of a direct current circuit which the circuit breaker controls. The parts of the device are so proportioned that when the current in the circuit exceeds a certain given 'value, magnet 2 will be sufficiently powerful to raise armature 4 unless this armature is held down by a force other than gravity. One feature of my invention is the provision of means controlled by current in the circuit for exerting such another force on the armature during a momentary surge of current above the given value, but not during a prolonged current in excess of the given value, so that the armature 4L will not be raised by magnet 2 during a momentary surge of current above the given value. This means I will now describe.

Magnet core 3 is provided with a winding 10 which is included in a local circuit which is in inductive relation to the main or line circuit, so that variations in value of the current in the main circuit will cause currents in the circuit of winding 10. As here shown, this'inductive relation is secured by placing a second winding 11 on core 2 and connecting it in circuit with winding 10, the circuit between windings 11 and 10 being completed by conductors 12 and 13. Since the line circuit which feeds winding 7 carries direct current, it is obvious that when the value of the current therein is constant, no current will be induced in winding 11 and winding 10 will therefore not beenergized, so magnet 3 then exerts no force on armature 1-. But when the value of the current in the line circuit varies, current will be induced in winding 11 during the period of such variation, and magnet 23 will then be energized and will exert force on armature 1.

The operation of the parts of the device thus far described is as follows: As long as the current in the line circuit is equal to or below the given value, magnet 2 is not strong enough to raise armature it against the force of gravity. Assume now that a momentary surge of current above the given value occurs in the circuit controlled by the breaker; during the time the current is increasing in value, current in one direction is induced in winding 11, and while the line current is de creasing in value current in the other direction is induced in winding 11, hence during the entire surge magnet 3 is energized and prevents the armature 1 from being raised by magnet A comparatively small current in winding is suiiicient to prevent armature 1- being raised by magnet 2 even when the winding 7 of this magnet carries a comparatively heavy current, because of the relatively small air gap between the armature and polepiece 3, and the relatively large air gap between the armature and pole piece 2. Assume now that the current in the circuit controlled by the breaker rises above the given value and remains substantially constant at a value above the given value. While the current is rising, induced current will flo as before in magnet winding 10 and the armature 1 will be held down, but as soon as the line circuit current becomes constant the induced current ceases so that magnet 3 no longer exerts a force on the armature, and magnet 2 then raises the armature against pole-piece 2.

The armature t may be employed to control one or more contacts in any desired manner. As here shown, a stationary carbon block 1 1 is mounted in a support 16 of insulating material fixed to the upper leg of the yoke 1, and another carbon block is carried by a spring 17 which is mounted in a block 18 of insulating material fixed to the lower leg of the yoke 1. The spring 17 tends to straighten itself out so that contact 1l15 is open, but the spring may be held by suitable means in such position that this contact is closed. As here shown, this means comprises a latch 19 pivotally conn cted with the spring at point 21 and hav ing a shoulder 19 adapted to engage a. hook 2O fixed to the block 18. This latch 19 may be kicked out of hooking engagement with hook by a toe at fixed to the armature 4, so that when the armature is raised it causes contact 1115 to be opened. The spring 17 may be replaced to the closed position by a handle Contact 1 l15 is included in the circuit controlled by the circuit breaker;

in Fig. 1 I have indicated diagrammatically a circuit which may be traced as follows from battery 39 through a switch 38, a motor 37, wire 9, winding 7, wire 8, contact 1 115, spring 17, wire to battery it is understood that this circuit is purely illustrative, and that a circuit breaker embodying my invention is not limited to use in a circuit of this type.

The circuit breaker shown in Fi 2 is substantially the same as that shown in Fig. 1, except as 10 the windings of magnets :2 and 3. Referring to Fig. 2, the winding for magnet 3, which I have here designated 10.

is formed of wire whose resistance increases with increase of temperature; for example, it may be of iron wire, the resistance of which at red heat is approximately three times its resistance when cold. This \Yilld. ing is energized from the line circuit in any suitable manner, for example, as here shown by connecting it in shunt to the winding 7 for magnet 2. The branch including winding 10" is from wire 8 through wire 21, winding 10, wire 27 to wire 5). Winding 10 will then always carry current when current is flowing in the line circuit. The parts of the apparatus are so proportioned that when the current in the line is below the given value at which it is desired that the circuit breaker should operate, the current flowing in winding 10 is of such value that the temperature of the wire in this winding is comparatively low. The resistance of this winding is then comparatively low and this winding then takes a certain portion of the total current flowing in the line circuit, so that armature 1- is held down with considerable force by magnet The portion of the current which then flows in winding 7 is insuiiicient to cause magnet 2 to raise armature 1 against gravity and the action of magnet 3. \Vhen, however, the current in the line circuit rises above the given value, and remains above this value for a definite length of time. the temperature of the wire in winding 10 rises. The resistance of winding 10 then increases so that winding 7 then carries a larger proportion of the total current than before, and the current in this winding is then sullicient to cause magnet 2 to raise armature 1 against gravity and against the action of magnet 3, thereby opening contact 1-115. llut during a momentary surge of the line current above the given value there is not suilicient time for an appreciable rise of temperature of winding 10, and the increased current in winding 7 is not suilicient to raise armature hence the circuit breaker will not be op res Then, obviously, it will remain closed for a shorter length of time on a current higher than this certain value, and for a longer length of time on a lower current. The core pin which separates armature 4 from polepiece 3, and which is designated by 5 in Fig. 2, is here shown as being comparatively long, for the reason that winding 10 is energized when the circuit breaker should kick off, and if the air gap permitted by this core pin were too short the armature would be held down by even the small current then flowing in winding 10 It is understood that the circuit breaker shown in Fig. 2 may be included in a circuit which is similar to the circuit shown in Fig. 1.

Referring now to Fig. 3, the circuit breaker here shown is similar to that shown in Fig. 2, except that the lower magnet 3 is omitted, and a coil of iron wire 10 is connected in shunt to winding 7 by wires 24 and 25. In this modification the armature 4 is held down by gravity only. The parts are so proportioned that when the current in the line circuit is below the given value at which it is desired that the circuit breaker should operate, the current then flowing in coil 10 is of such value that the temperature of the wire in this coil is comparatively low. The resistance of this coil is then comparatively low, and it takes a certain proportion of the total current flowing in the line circuit; the balance of the current, which flows in winding 7, is then insuflicient to raise armature 4. When, however, the line circuit current rises above the given value and remains above this value for a certain length of time, the temperature and consequently the resistance of the coil 1O rise, so that the winding 7 then carries a larger proportion of the total current than before, and this current is sufficient to raise armature 4. But during a momentary surge of the line current above the given value, there is not suflicient time for an appreciable rise of temperature of coil 10*, so that the current in winding 7 is not suliicient to raise arma ture 4 and the circuit breaker is therefore not operated. As explained hereinbefore in connection with Fig. 1, the parts may be so designed that the circuit breaker will remain closed for a definite length of time when subjected to a current of a certain value above the given value. This circuit breaker may be included in a circuit which is similar to that shown in Fig. 1.

Referring now to Fig. 4, I have here shown a circuit breaker of the solenoid and plunger type embodying my invention. This circuit breaker, in the form here shown, comprises a rectangular frame 26 of magnetizable material, preferably soft iron, provided with a cross-piece 27 of similar ma terial. The upper part of the frame 26 is provided with a threaded hole 26 into which is screwed a core 28 of magnetizable material, also preferably soft iron, which core is held in place by a nut 28. The core 28 is provided with a central longitudinal hole 31 through which freely passes a stem 30 of non-magnetizable material such as brass, the lower end of which screws into a plunger 29 of magnetizable material, usually soft iron. This plunger passes freely through a hole 27* in the cross-piece 27, so it will be seen that the plunger 29 and stem 30 are free to reciprocate in a vertical path, being guided by the hole in the core 28 and the hole in crosspiece 27. The downward movement of the plunger is limited by a stop comprising a pin of non-magnetizable material screwed into the bottom of the frame 26 and locked by a nut 32 the upward movement is, of course, limited by the engagement of the plunger with the core 28. The core is provided with corepins 33 of non-magnetizable material to prevent actual contact of the core with the plunger. 7 is a solenoid winding which surrounds the core 28 and a portion of the plunger 29, and which forms part of a direct current circuit controlled by the circuit breaker. The parts of the device are so proportioned that when the current in the circuit exceeds a given value, solenoid 7 is sufiiciently energized to raise the plunger 29 unless the plunger is held down by some force other than gravity. As here shown, the means for holding the plunger down during momentary surges of current above the given value is substantially the same as the means shown in Fig. 1; that is, I provide a winding 10 in the form of a solenoid surrounding the plunger 29, which winding is in series with a winding 11 which latter is in inductive relation to the operating winding 7. The operation of the parts of the breaker thus far described is substantially the same as the operation of the form shown in Fig. 1. That is, during a momentary surge of current in the circuit controlled by the breaker, current is induced in winding 11, and the current which consequently flows in solenoid 10 exerts sufiicient influence on the plunger 29 to prevent the latter being raised by solenoid 7. \Vhen. however, the current in the circuit controlled by the breaker remains substantially constant at a value higher than the given value, no current flows in solenoid 10, so that solenoid 7 is then effective to raise plunger 29. The plunger 29 may be employed to control one or more con tacts in any desired manner. As here shown, a spring 17 is mounted in a block 33 of insulating material secured to the frame 26, and this spring is included in the circuit controlled by the breaker in the same man ner as in the preceding Views. In Fig. 4 the spring is provided with a hook 34 which coacts with a latch 35 pivoted in the block The upper end of stem 30 carries a head 36 of insulating material, which, when the plunger is raised, strikes the latch 35 and so releases the spring 17. The circuits {or the solenoid winding 7 and for the re tarding winding 10 are the same as those shown in Fig. 1 and hereinbefore explained. This circuit breaker may be included in a circuit which is similar to the circuit shown in Fig. 1.

Circuit breakers embodying my inven tion are adapted for the protection of any circuit wherein it is desired that the circuit should be opened when the current is pro longed above a given value for an appreciable length of time, but wherein a mo mentary surge of current above the given value will cause no harm so that it is undesirable that the circuit should be opened by such a surge. They are, for example, particularly well adapted for the protection of motor circuits. The current drawn by a motor while starting is considerably in excess of that which is drawn after the motor is in operation, but this excess of current is only a momentary surge and does no harm to the motor or other parts of the circuit; it, however, the motor is stalled or operates too slowly and the circuit is not opened. the prolonged excessive current will injure the motor or other parts of the circuit. lVhen a circuit breaker embodying my invention is used to protect a circuit of this character it is adjusted to operate on a prolonged current slightly in excess of ti it drawn by the motor when operating on full load. Then if the motor is stalled or operates too slowly, the circuit breaker will be operated by the prolonged excessive current, but the circuit breaker will not be operated by the momentary surge of current while the motor is being started.

Circuit breakers embodying my invention are also well adapted for use in circuits for the propulsion current for electric railways, in which case the circuit breaker is usually adjusted to operate when the current exceeds a safe maximum value. There are times when this maximum value is exceeded for a short period of time, such, for example, as when a large number of cars or trains are started at once. and it this period of time is not too long the excessive current will do no harm. Circuit breakers embodying my invention can be adjusted to remain closed during a short period of such excessive current, but to open it the excessive current is prolonged tor a suiiicient length of time to be harmful.

Although I have herein shown and described only a few forms of circuit breakers embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, an electric circuit; and a circuit breaker comprising a winding e11- ergized from said circuit, a member adapted to be moved by said winding when the current in the circuit exceeds a given value, a second winding adapted to prevent movement of said member by the first winding, means controlled by current in said circuit and responsive to mtm'ientary surges of said current above the given value for energizing said second winding, and a contact controlled by said member for controlling said circuit.

In combination, a circuit carrying direct current; and a circuit breaker com prising a winding included in said circuit, a member adapted to be moved by said winding when the current in the circuit exceeds a given value, a second winding adapted to prevent movement of said member by the first winding, means for energizing said second winding inductively from said circuit whereby the second winding will be energized by a momentary surge of current above the given value in the circuit and will prevent movement ot the member by such.

surge, but whereby the second winding will not be energized by a. constant current in excess of said value and will therefore not prevent movement of the member by such constant current, and a contact controlled by said member for controlling said circuit.

3. A circuit breaker comprising a winding, a member adapted to be operated by said winding when the current in the winding exceeds a given value, a second winding tion to the first winding, and a contact controlled by said member.

l. A circuit breaker com 'irising an electromagnet having two windings, means for energizmg one o't said windlngs with di rect current, an armature adapted to be on erated by said magnet when the current in the said energized winding exceeds a given value, a second electromagnet adapted to prevent operation of the aru'iature by the first-mentioned magnet, the winding of the second magnet being connected with the remaining winding of the first magnet, and a contact controlled by said armature.

5. In combination, an. electric circuit, a movable member, means controlled by current above a given value in said circuit for and a contact controlled by said member for opening said circuit.

6. In combination, an electric circuit, a movable member, means controlled by current above a given value in said circuit for moving said member in one direction, means responsive to a momentary surge of current in said circuit above said given value but not responsive to a current of constant value regardless of such value for exerting a force on said member in the opposite direction to prevent its movement, and a contact controlled by said member for opening said circuit.

7 In combination, an electric circuit; and a circuit breaker comprising a Winding energized from said circuit, a member adapted to be moved by said Winding When the current in the circuit exceeds a given value, a second Winding adapted to prevent movement of said member by the first Winding,

means controlled by current in said circuit and responsive to momentary surges of said current for energizing said second Winding, and a contact controlled by said member for controlling said circuit.

8. In combination, an electric circuit, a movable member, means controlled by current above a given value in said circuit for moving said member in one direction, means responsive to a momentary surge of current in said circuit for exerting a force on said member in the opposite direction to prevent its movement, and a contact controlled by said member for opening said circuit.

In testimony whereof I afiix my signature in presence of two Witnesses.

HOWARD S. BEAKES.

Witnesses:

A.- HERMAN VVEGNER, R. L. KISTLER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G.

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