US833178A - Means for opening and closing electrical circuits. - Google Patents

Description

No. 833,178. PATENTED OCT. 16, 1906.

G. RENNERFELT.- MEANS FOR OPENING AND CLOSING ELECTRICAL CIRCUITS.

APPLICATION FILED JUNE 11, 1904.

s SHEETS-SHEET 1 WITNESSES; INVENTOR: 456M PATENTED OCT. 16, 1906.

C. RENNERFELT.

MEANS FOR OPENING AND CLOSING ELECTRICAL CIRCUITS.

APPLICATION FILED JUNE-11, 1904.

3 SHEETS-SHEET 2 By his Alto/nay,

PATENTED OCT. 16, 1906.

a sums-sum a G. RENNERFELT.

MEANS FOR OPENING AND CLOSING ELECTRICAL CIRCUITS.

APPLIOATION FILED JUNE 11, 1904.

' V x. ,IIIIIIIIIIIIIIIM INVENTOR: W W

By his Attorney WITNESSES:

UNITED STATES PATENT oFFIoE.

GUSTAF RENNERFELT, OF SORANTON, PENNSYLVANIA.

Specification of Letters Patent.

Patented Oct. 16, 1906.

A li ation filed June 11, 1904. Serial No. 212,127-

To all whom it may concern.-

Be it known that L'GUSTAF'RENNERFELT, a subject of the King of Sweden and Norway, residin at Scranton, county of Lackawanna, State 0 Pennsylvania, have made a new and useful Invention in Means for Opening and Closing Electrical Circuits, of which the following is a specification.

My invention is directed to improvements in means for openim and closing electric circuits in general, and especially such circuits as include electric motors. I

The objects of my improvements are, first, to provide an electric switch or circuit-. breaker having a time-constant whereby the circuit may be opened if it is subjected to a prolonged overload, but may remain closed if the overload is of short duration; second, toprovide simple means for adjusting such a switch so that the same device may be used for different loads; third, to provide means for magnetically blowing out the are which is formed at this switch when it operates; fourth, to arrange the associated parts of the switch so that it will be simple of construction and reliable in its operation; fifth, to provide means for closing and opening said switch; sixth, to prevent sparking at auxiliary contacts necessary for operating the switch, the arrangement being such that all of the sparking is confined to the contacts of the switch and also such that waste of energy in the controlling solenoids or magnets used inthe apparatus shall be reduced to a minimum; seventh, to provide novel means for obtaining proper pressure for good contact on the controller and to rovide that the same means shall extinguish sparking on the contacts of the controller, and also that they shall serve to retain the controller in a certain position; eighth, to provide means for an automatic economical and reliable cooperation of the aforesaid circuit breaker and controller in eneral, and especially so that no sparking s all occur in the auxiliary contacts necessary in the combination, all sparking being confined to the contacts of the circuit-breaker, and also so. that waste of energy in the solenoids or magnets used in the a paratus may be reduced to a minimum.

his especial feature the reduction to a minimum of the energy wasted in the magnetsis of particular value, not only from the point of view of mere economy, in so far as it tends to lessen the cost of construction, the cost of operating the apparatus, and the cost of keeping it in repair, but it is also of especial value in that it makes it possible to operate the same magnets with either alternating or direct current.

My invention, which to some extent relates to improvements in ap aratus described in United States Patent *0. 7 69,406, ranted to me September 6, 1904,-will be fully understood by referring to the accompanying drawings, in which- Figure 1 is a plan view of'my novel switch. Fig. 2 is a sectional view thereof, taken on the broken line A A, Figs. 1 and 3, and as seen looking thereat from right to left in the direction of the arrows. Fig. 3 is a sectional view taken through Fig. 2 on the broken line B B and as seen lookin thereat from left to right in the direction 0 the arrows. Fig. 4 is a sectional view taken through Fig. 2 on the line C C and as seen looking thereat from the top toward the bottom of the drawings in the direction of the arrows. Fig. 5 is a plan view of the controller, Fig. 6 is a sectional view thereof, taken through Fig. 5 on the line D D and as seen looking thereat from left to right in the direction of the arrows. Fig. 7 is an end elevational view as seen looking at Fig. 5 from the top toward the bottom of the drawings, the controlling-magnet for regulating the pressure between the contacting s ring and the contact-blocks of the rheostat eing shown in sectional view; and Fig. 8 is a diagrammatic view showing the appllcation of my entire improvement 1n a system of motor-control and as connected with a water-tank adapted to be filled by a pump driven by the controlling-motor, the same figure illustrating also novel means for automatically disconnecting the motor from the circuit in the event of overload, due to any cause whatever, such disconnecting means 7 being in the nature of a thermal device which is actuated by an abnormal flow ofcurrent therethrough. r

Referring now to the drawings in detail, 1 represents the insulating-base of the switch, supported in any preferred manner."

2 and 3 represent the conducting-terminals of the switch, and 4 the yielding contactarms thereof, made, preferably, of thin stri s of sheet-copper and pivotally securedto the terminal 2 by a head 5, which is connected in turn by a link 6 to an operating-handle 7, provided with a strong spiral spring 8, the tendency of which is to rotate the handle 7 in the direction of the arrow, Fig. 2.

9 is a roller carried by the switch-head, and 10 is a locking-trigger for locking the sw1tch in its closed position, said. trigger being connected to an msulating-base-l 1, carried by an armature-lever 12, located in front of the core 13-of a magnet 14.

15 is a retractile spring for the armaturelever 12, adapted to hold it in the position shown in Fig. 3, so that the trigger 10 will rest against the roller 9 and lock the switch.

The plate 11' is of insulating material and also acts as a baffle late or shieldto separate the two termina s of-the switch.

16 is arubber buffer adapted to make a cushion-stop for-a lug- 17, secured to the handle 7, when the switch is automatically released under the influence of the strong spring 8. 4

18 is a stationary carbon contact secured to the terminal 3, and 19 is a movable carbon contact being carried by a yielding spring 20, secured to the head of the. switch by screws,

,(see Figs. 2'and 4,) the function of said terminals-being to interrupt the circuit without danger of fusing the parts.

.2-1 is the stationary contact-block for the free end of the yielding switch-arm '4, said .block being of non-magnetic metal, preferably copper.

The extensions of the pole-pieces of the ma et 14 are so constructed and located wit relation to the stationary contact 21 that the magnetic lines of force flowing therefrom will tend to extinguish the are between the movable and fixed terminals of the switch when the circuit is interrupted.

22- is an automatically-movable contact,

made, preferably, of two thin strips of metal ofulifl'erent coefiicients of expansion and sol-' dered together.

' 23 is a carbon pencil secured in aslit in the manner shown in Figs; 2 and 3 and adapted .to contact with the stationary contacts 24 or a description of the controller, 26 represents,

t e insulating-base, and 27 thecontrollerart m, pivotally secured thereto and carrying at its free end a sliding contact-plate 28, adapted-to contact at one end'agalnst aseries of rheostat segments or contacts 29,

mounted upon the base 26 and connected to successive coils thereof, and at the other end against theundersurface of acontactlate 4 30, secured at its opposite ends direct y to the base, the arrangement being such that the free .end of. the controller-arm and the sliding contact-plate 28, carried thereby, will move between the plate 30 and rest upon the segments or contacts 29 as the arm is moved in either direction. I 4

31 is a weight secured, as in Fig. 5, to the end of a lever carried by the controller-arm 27 and adapted to normally hold said controller-arm in the off position, so that all of the rheostat-coils are in circuit. 32 is an electromagnet secured at the outer end of the controller-arm 27 and provided with an armature-lever 33, pivotally secured to its core, so that the short arm thereof shall support one end of the contact-plate 28 and press it against theunder surface of the plate 30. The other-end of the contact-plate '28 is secured to the core of the magnet 32 and is pressed against the segments or contacts '29.

34 is a magnet secured to and carried by the controller- arm 27, and 35 is an iron arm pivotally secured to the controlling-arm, 36 being a section of a-half-nut supported in a slot in the outer end of the arm 35 and in such manner that-when the circuit is closed through the magnet 34 the screw-threads ofv the half-nut will be brought into mechanical connection with the screw-threads of the screw 37 against the stress of a leafspring 38, carried by the arm 35 and resting on the pole of the magnet 34.

Referring now to Fig. 8, 5O designates an pump 70. This pump is connected to a reservoir or tank'71 by a pipe 72 and is arranged'to pump water through a pipe 73 into another water-tank 74. A float 39 is attached to the inner end of a lever, which is pivoted upon one edge of this water-tank 74, the outer end of said lever being provided with an electric contact-plate adapted to make circuit between two contacts 42 when the water has reached'lowlevel and at two additional contacts 43 when the tank has been filled. As illustrated in the drawings, the water is at low level and the pump-motor has just been connected in circuit by the closing of the automatic switch. This closing is effected by the lifting-of'the core'44 by the solenoid 45, which when contacts 42 are bridged will receive current by the following circuit: from the positive current-feeder 46 through the branch feeder 47, contacts 42, solenoid 45, branch feeder 47 adjustable contact 48', thermostatic .device 49, branch feeder 50, armature 51 of the motor, to the negative current-feeder 52. Consequently the solenoid 45 lifts the iron core 44, which is connected to the switch, so that the motorcircuit is closed from the branch feeder 50 I through the yielding switch-arm 4, thus bridging between the terminals 2 and 3 to y S I remains in circuit, so that its armature pivreceive .current from contact-plate of the rheostat, sliding contact-plate 28, coils series wit the shunt-field 53, and the mag-- net 34 will cause the sectional half-nut 36 to engage with the screw 37, so that when the armature 51. of the motor starts this screw will be rotated in pro er direction'by reason of the belt 57 and pul ey 58, as illustrated in Fig. 8, to cause the upper end of the controller-arm 27 to move from right to left, thus gradually causing the contact-plate 28 to,

successively move across the rheostat segments or contacts 29, and to thereby cut the resistance-coils out of the motor-armature 7 the motor still continues to run and rotate the screw 37 the controller-arm will not be advanced any farther. The magnet 32 still otally supported by the core will cause one of the free ends of the contact-plate 28 to bear with considerable friction against the under surface of the curved plate 30, and additional friction will be exerted on the other end of the contact-plate 28 between the core of the magnet 32 also performs another im-' .portant function in that by reason .of the magnetic field set up as it passes over the rheostat segments or contacts 29, which are preferably of iron, the lines .of force blow out any spark which may result as the plate 28 passes from segment to segment. It will be noted that the solenoid 45 is so connected that the current flowing through it will be gradually decreased, as the starting resistance is cut out by the rotation of the controller-arm 27 from right to left, and no current will flow through said solenoid when all of this resistance is out of circuit.

This feature constitutes. an important part.

of my invention and is made the sub ectmatter of claims hereinafter. If this solenoid were so connected that current passed through it all the time that the motor isrunring it would not be possible to open the switch by such simple means as I provide,

and, furt rmore, considerable energy would be wasted by constantly maintaining the solenoid in circuit, whereas as now constructed when the starting resistance is all cut out of circuit both terminals of the solenoid are connected. directl to the same currentmain. "If this 'sofenoid were connected in 1 the ma such manner that it became denergized by the closing of contacts 2 and 3, it might possibly happen that it would not act a sufficient length of time to give proper pressure on the arm 7 and cause the locking of the switch,

which occurs, as is illustrated in Fig. 3, when ,tor-armature, so that by reason of the variable drop of potential in the starting resistance I gain a result such that there will be sufiicient current through the solenoid to close the switch with certainty and yet prevent waste of energy in the solenoid while the motor is running.

Suppose now that the'water has risen in the tank to its extreme limit and that the contact-plate 41, carried by the pivoted lever controlled by the float 39, has made contact with the two contacts 43, owing to the rising of said float. When the circuit was interrupted.at the contacts 42, no spark occurred because, as before stated, no current was flowing through the solenoid 45, there being no difference of potential between the ends ofits coil. When the water has risen, therefore, to the highest level and the contacts 43 established, as stated, this will cause a current to flow through the branch circuit 50 from the positive main 46 through the switch terminals 2 3 to the contact-plate 30, branch circuit 59, contacts 43, branch circuit 59, coils of the magnet 14, branch circuit 59, .to the negative main 52, thus energizing the magnet 14 and causing the same to act upon the armature-lever, which controls the oper-. ation of the trigger 10, thereby releasing the roller 9 and allowing the spring 8, which controls-the opening of the switch, to quickly remove the free end of the yielding contactarm 4 from the stationary copper contact-bar 21 and also the carbon-term1nal19 from the stationary carbonterminal 18 (following later) opening the circuit without arcin When the main circuit is thus finally opene et 32 'is denergized, and the counterweig t 31 restores the controller-arm 27 to its off positionthat is, the Iposition shown in the diagrammatic view, ig. 8and re- 1 places all of the starting resistance in the motor-circuit. During this movement of the controller-arm 27 there is onl little pressure and friction between the s 'ding contactplate 28, the rheostat-segments 29, and plate 30, since the magnet 32 has been demagnetized.

If the motor should happen at any time to be subject-ed to a prolonged overload caused, for instance, by a hot ournalbearing, the circuit will be opened in the followingmanner: The thermostatic device 22 isso combined with the circuit that it is heated by the current, and when it reaches a certain temperature 1t establishes a contact 22 24,

I which, as clearly seen from the diagram, will have the same effect on the switch as has the closing of the contacts 43, the switch will be opened, the motor will stop, and the startlng reslstance will be reinserted into the motor-circuit. The preferred form of this thermostatic' device consists of a metallic strip and is included in the circuit sot at itis traversed and heated by the main current or by a definite amount of the main current. A

resistance 60 may be connected in shunt to' the strip 22 to take a part of this current. When the strip 22 is heated, it assumes a curved shape, and the contact 24 is so adjusted that it will be touched by the strip when it has reached a certain temperature;

When this happens, the magnet-winding 14 I will receive current through the following clr'cuitzfrom the plus main 46, through branch conductor 50, terminal 2, yielding switch-arm 4, terminal 3, conductor 50, plate 30, sliding contact-plate 28, conductor 50, thermostatic device 22, contact-point 24,

branch conductors 61 and 59, colls of the magnet 14, to main 52. Consequently the trigger 1-0 is withdrawn and the switch opened as before by theaction of the spring 8.

Upon separation 'of the contacts 22 24 there will be no spark there, since the circuit is already broken on the switch at 19 18. F A push-button or similar device 62 may be arranged in a branch circuit 63, whereby ghe- 1s-- switch can at any time and from any tance be opened manually, and it will be noted that the connection for this push-button is such that no spark will occur at its terminals, for reasons before pointed out.

It will be observedthatthestrip 22. cannot make contact with the adjustable. contacts 48 24 at the same time, and the solenoid 45 and magnet 14can therefore never be ener-.

gized through the contacts simultaneously.

This would happen if there were permanent,

connections from the solenoid 45 to the plus brush of the armature 51 and if the contacts 42 were established while the strip 22 was sufliciently hot to touch the contact 24. Such a condition would prevent the locking of the switch by the trigger 10 and roller 9 and would cause arcing of thecontacts 18 and 19. By connecting the solenoid 45, as shown, to t e contact 48 1 effect the result that after the motor-circuit has been automatically overloa again before some time has elapse This time will be long enough to allow the thern'ur opened, by reason of a prolonged it will not be automaticall closed static device 22 to cool off sufliciently to establish the contacts 48 22, and during this time the motor, which is included in circuit with the strip 22, will also cool somewhat, so as to be better adapted to stand the-overload in case it should still exist when-the circuit is established. Should a hot bearing causethe overload, the bearin will have a chance to cool, and the overloa may perhaps have disappeared when the circuit is closed again, due

.to the making of contact between the strip 22 current is of shortduration, and its heating effect on the motor is not great unless the with, but also for the purpose startin is fre uently repeated. Neither will its lieating e ect be great on the thermo-- static device 22, and for this reason this de vice will not act so as to open the circuit for an overload of such .short duration as that.

due to starting. It will, however, open the c1rcu1t for an overload which lasts' during some time-that is, such a length of time as will endanger the motor and will cause the temperature of the thermostatic device to rise to the predetermined limit-and it isevident that such an overload may correspond to a current which is much smaller than the starting-current. p p

It must be well understood that the. mode of operation of the switch or circuit-breaker here described is very different from that of the well-known types of circuit-breakers which open the circuit when the current attains a certain strength and which when motor will not open the circuit for an overload due to a current smaller than the starting-current. It should also be noted with regard to the controlling devices shown as assembled in diagrammatic view in Fig. 8 that their operation is performed in a very economica manner 1n view of the fact that there is no energy wasted in the magnetwindings 14, 34, and 45, which are tempura: rily energized only at the time when theyhave to perform actual mechanical work. The only winding which utilizes continuously some amount of energy is 32, and as the force required of this magnet is not heavy it will be apparent that by properly designing the air-gap and other details of the magnet 32 the amount of energy there wasted can be limited to a mere trifle. It might be added that in case of cessation of the voltage at the mains 46 and 52 the switch will not be 0 ened; but since the magnet 32 will become eener- "used in simple combination with an electric gized the arm 27 will be brought to its off position, where all the starting resistance-will e reinserted into circuit with the motor.

When the voltage again appears and the motor starts up, the resistance is again out out from the circuit.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is

1. In an electric circuit, the combination of a contact-block 21, a switch-arm 4, a magnet for moving the arm into contact with the block, means for energizing the magnet and automatic means for gradually decreasing to zero the current in said magnet.

2. In combination with an electric motor having an armature, a circuit for the armature, a switch in saidcircuit, a latch for holding the switch closed, a spring for opening the switch and a magnet arranged to release said latch, said magnet having a winding in the action of the spring, automatic means for direct shunt with the motor-armature.

3. In an electric motor, the combination of a contact-block, a switch-arm, a s ring arrangedto se arate the switch-arm cm the contact-bloc a magnet arranged to move the arm into contact with the block against the action of the spring, means for energizing the magnet, and means for gradually de-' creasing the current in the magnet to .zero a latch for holding the arm against the contactblock, and a ma et for releasing the latch.

4-. In an electric motor, thecombination of a contact-block, a switch-arm,-a spring arranged to se arate the switch-armfrom the contact-bloc a magnet arranged to move the arm into contact with the block against energizing the ma net, and means for gradually decreasing t e current in the magnet tozero; a latch for holding the arm against the contact-block, a magnet forreleasing the latch, and means for automatically energizing said releasing-magnet.

5. In an electric circuit, the combination of a motor, a starting resistance therefor, an electrically actuated starting-switch, a ma net arranged to close the starting-switc said magnet having a winding connected .in shunt to the starting resistance. a

6. In combination with an electric motor,

' a device arranged to automatically stop the I I motor when said'device is heated to a predetermined degree and to automatically start the motor when cooled to a predetermined degree, the temperature of said device being arranged to be proportionalto that of themotor. i 7. In combination with an electric motor,

an automatic thermostatic device arranged to break the motor-circuit when current in said circuit is excessive, and to close said circuit after an elapsed time, the length of said time depending upon the amount of said ex cess current.

8. In combination with an electric motor having an armature, a starting-switch therefor, a latch for holding the switch closed, a

spring for opening the switch, an' electromagnet arranged to release the latch, said ma net having a winding connected in shunt to t e armature of the-motor, and athermostat in series with the motor-armatureand arranged to be actuated by said currentand arranged to close the circuit through the magnet.

v9. In combinationwithan electricmotor a resistance in series with themotor, a-starting-switch for the motor, a magnet arranged to close said starting-switch, said magnet having a winding connected in shunt to said resistance, and means for retaining the switch in its closed position.

.10. Thecombination with a source of eleetrical supply, of a circuit, a thermostat in said circuit arranged to be heated by current from said source of supply, a second electric circuit derivin current from said source of supply throug the thermostat, a contactpiece located in said second circuit in close proximity to the thermostat, and means for adjusting the relative position of the thermostat and the contact-piece.

l 1. The combination with a source of elec-' trical sup ly, of a translating device connected to'sai source ofsu ply, a thermostatic device in series with sald translating device,

a switch also in series with the translating device, a magnet having a winding andarranged, when energized, to open said switch,

a contact-piece located in the circuit of the too magnet-winding and adapted to come into electric contact with the thermostat when the latter is heated to a predetermined decc, and means for adjusting the distance etween the thermostat and the contactpiece. r

12. The combination with a source of electrical sup ly, of a translating device connected to said source of electrical supply, a ther- TIO ' mostatic device in series withthe translating device, a switch also in series with the translating device, a magnet having a winding and arranged, when ener 'zed, to close the switch, afcontact-piece ocated in the circu1t of the magnet-winding and adapted .to come into electric contact with the thermostat, and means for adujsti the distance between the thermostat an the contactiece.

13; The combination with a source 0 electrical supply, a translating device connected to said source of supply, a switchinseries with the translating device, a magnet having a wind' arranged, when energized, to close the SWiI/Iil, said winding being also in series with the translating device, means for retairiing the switch in its closed position, a thermostat inseries with the translating device, and means operated through the thermostat for opening the switch.

ITS

tor.

14. The combination of an electric motor having an varmature, two contacts in series with the armature, a starting resistance, an electromagnet in series with the armature and in-shunt to the starting resistance, means I actuated by the electromagnet for closing the contacts, and means for retaining the contacts in closed position.

]5.- The combination of a motor, a circuit for the motor, means for closing the circuit, a

thermostatic device dependent u on its tem-' perature for delaying the time o the closing ofisaid circuit, and means dependent on its temperature for opening the motor-circuit, the thermostatic device arran ed to have its temperature proportional to that of the mo- 16. The combination of an electric motor,

I a starting-switch therefor, a magnet arranged,

magnet arranged, when energized, to openwhen energized, to close the switch, a second the switch, circuits for the "magnets, and a thennostatthrough which one or the other of said magnet-circuits may be energized, said-thermostat being in series with the motor. 1 I

17. The combination of an electric motor, a starting-switch therefor, a magnet arranged,

' 'whenenergized, to close the switch, a second magnet arranged, when energized, to open the sw-1tch, c1rcu1ts for said magnets, an automatic 'sw tch for closing one or the other of said ma 'net circuits, and a thermostat in cirmotor, a tank hydraulically'connected with the pump, a switch arranged to be-actua'ted by t 0 level pf water in saidtank to close the circuit of said first magnet when the waterlevel is low and to close the circuit of said second magnet when the water-level is high,

. and a thermostat in circuit withthe 'motor and arranged to control said magnet-circuits. 19 In combination with an electrical source of supply, a circuit deriving current therefrom, a metallic strip includedin said circuit and arranged to bend when heated by the current, a contact in close proximity to the strip, and means for adjustmg'the pdsiden of the contact relative to the strip, said contact being arranged to be brought into or out of electric connection with the strip .upon

a movement of the strip, and means for avoiding breaking of any current at said contact.

20. In combination with an electric circult, aswitch therefor, means for retalmng the switch in 1ts closed pos1t1on, a magnet,

and means coeperating with the. magnet to 6 open the switch when the magnet is energized, a thermostat included in the circuit, and through which the magnet may be energized, and a resistance in shunt to the ther mostat so arranged that a definite part of the currentin the circuit will flow through the thermostat.

2 1 The combination of a switch, a spring arranged to open the switch, a magnet arranged to close the switch against the action of the sprin a circuit for said ma et, a contactswitc arranged to be close and opened in said circuit, means for holding the first switch closed, a magnet for releaslng the holding means, a circuit for the releasing-magnet, a contact-switch arranged to be closed and opened inthe releasing-magnet circuit, said circuits and contacts arranged to avoid the breaking of any current at either of said contact-switches.

22. The combination with a source of electrical supply, of a thermostat arranged to be heated b a current from said source of supply, an e ectric circuit derivin current from said source ofsu ply through t 1e thermostat, a contact-piece coated in the circuit in close proximity to the thermostat, a carbon piece attached to the thermostat opposite to said contact-piece, and means for adjustin the relative position of the thermostat an the contact-piece.

23. The combination with a source of elec-- trical supply, of a thermostat arranged to'be heated b current from said source of supply, an e ectric circuit derivin current from said source of supply throug the thermostat, a contact-piece coated in thecircuit in close proximit to the thermostat, and means for adjusting the relative position. of the thermostat and the contact-piece.

24. In combination with, an electrical source of supply, a circuit deriving current therefrom, a metallic strip included in said circuit and arranged to bend when heated by the current, a contact included in the circmt in close proximity to the strip,- and means for adjusting the position of the contact relative to the strip.

'25. In combinationwith an electric eircuit, an automatic thermostatic device in eluded in the circuit and arranged to open the circuit after a time limit when'the current in said circuit reaches a predetermined amount, and to close the circuit after the

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