US2548060A

US2548060A - Electromagnetic operating and control system

Info

Publication number: US2548060A
Application number: US94692A
Authority: US
Inventors: Charles R Ray
Original assignee: PACIFIC ELECTRIC Manufacturing CORP
Current assignee: PACIFIC ELECTRIC Manufacturing CORP
Priority date: 1949-05-21
Filing date: 1949-05-21
Publication date: 1951-04-10
Anticipated expiration: 1968-04-10

Description

April 10, 1951 c, RAY 2,548,060

ELECTROMAGNETIC OPERATING AND CONTROL SYSTEM Filed May 21, 1949 IN VEN TOR. UHARLES E. RAY.

[from/5y Patented Apr. 10, 1951 UNITED STATES PATENT OFFICE ELECTROMAGNETIC OPERATING AND CONTROL SYSTEM ApplicationMay 21, 1949,;SerialNo..94,692

7 Claims.

The present invention relates to electromagnetically controlled apparatus and more particularly to an improved electromagnetic control system for an automatically operating reclosing circuit breaker of the type having an operating coil connected in series with the circuit breaker con tacts.

The primary object of my invention is to provide a magnetic control system in which a series coil is employed to control and operate a service interrupting and restoring circuit breaker under abnormal conditions in a novel manner which will avoid the losses that normally result from the use of such a series connected coil.

Another object of the invention is to provide an electromagnetic means for the control and;opera tion of electrical apparatus employing a series connected coil that is responsive to current flowing therethrough ,in which a maximum of magnetic effort is obtained in a novel manner ,for the operation of theapparatus in time of need and with ,a minimum of power loss during idle periods between theoperation of the apparatus.

Another object of the invention is co-provide a new and improved electromagnetic control and operating means for reclosing circuit breakers. of the ,type employing a single operating coilconnected in series with the circuit breaker contacts and in which .the power losses are reduced to a minimum during inactive periods in a novel manner, without any loss of the advantages in the use of such a coil under active operating conditions.

A further object of the invention is to provide an electromagnetic system employing a single series connected energizing coil in which two independently operating armatures are employed in a novel manner to reduce the power losses, resulting from the use of such a coil connection without at the same time reducing the effectiveness of such a coil connection'under operating conditions.

Another object of the invention is to provide an improved electromagnetic control for controlling and operating a reclosing circuit breaker of the type illustrated and described in a co-pending application for Letters Patent entitled Power Line Service Restorer, Serial No. 764,522, filed July 27, 1947, by me and one Joseph S. Thompson as joint inventors.

Other objects and advantages of the invention will be in part evident-to those skilled in thesart and in part pointed out hereinafter inconnec-- tion with the accompanying drawing wherein there is shown'by way of illustration and not of limitation apreferre'd embodiment of the invention.

In the drawing:

Figure 1 is a side view, partly in section, showing a reclosing circuit breaker of the pole mounted type to which my invention has been applied,

Figure 2 is a fragmentary view showing the reverse side of the elements of the invention shown in Figure-1 of the drawing, and

Figure 3 is a schematic wiring diagram showing the mannerin which the control circuits are established in accordance withthe invention.

While my invention may ,find many applications and uses .with circuit controlling apparatus employing an electric current responsive electromagnetic operating means withan energizing coil connected inseries with the circuit to be controlled, I have in Figure 1 of the drawing shown it as applied to a single pole circuit interrupting and restoring circuit breaker. of the so-called reclosing type. These circuit breakers, as is well understood in the art, are adapted .to open a faulted or overloaded circuit and then reclosega predeterminednumber of times until the fault or overload is removed from the circuit or the circuit breaker is finally locked in an open circuit position. In this particular figureof the drawing the circuit breaker isshown as having two spaced insulating bushings .IO and l I which extend through a supporting cover l2 that is carriedby an insulating fluid containing tank [3. The tank 13 has brackets 14 that accommodate tie bolts l5 by which the cover [2 is secured in place and which also serve as a means for mounting the circuitbreaker upon the cross arm of a poleor .a powerline carrying tower. The insulatingbushing H has a downwardly extending portion [6 which serves as a supportfor a circuit breaker operating mechanism, designated generally by the numeral 11, and associated with this operating mechanism I! there is an electromagneticfield structure [-8 that-has an energizing coil 19 which is connected in series with the circuit throughthc circuit breaker contacts. Associated with the electromagnetic field structure there is an operating armature 20 by which thecircuit breaker operating-mechanism i1 is operated. Extending outwardly from the operating mechanism I! there is a pivotally mounted arm 2| that carries a moveable contact 22 which is adapted'to be moved into and'out of circuit establishing relation with astationary contact (not'shown) that is mounted upon the lower end of. the terminal bushing; l 0 and enclosed with an arcing chamber .23.

The operating mechanism I1 .is also .here

shown as having an upwardly extending arm 24 of insulating material that is connected through a link 25 to a crank arm 26 of a timing mechanism 21. This timing mechanism 21 forms no part of the present invention and it therefore need only be here stated that in its operation it serves as is well understood to delay the successive circuit reclosing operation of the circuit breaker. In this particular arrangement, like that disclosed in the aforementioned co-pending application for patent, the operating mechanism I! employs a reclosing spring and latching mechanism (not shown) which upon each actuation of the operating armature 2B, in response to an overload or faulted condition, will cause the pivotally mounted arm 2! to move the movable contact 22 into a circuit open position and then complete a reverse movement thereof which will again bring the moveable contact 22 into its circuit closed position as here illustrated.

Upon now referring to Figure 2 of the drawing, it will be seen that the invention contemplates the employment of a low value resistance unit 28 that is mounted adjacent to and connected, as will hereinafter appear, in parallel or current shunting relation with the operating coil Hi. In order to render this low resistance unit 28 ineffective to shunt current around operating coil l9 during abnormal current conditions and at a time when a maximum effort is required of the operating armature 20, I have provided a second or auxiliary armature 29. This auxiliary armature 29 is also responsive to the electromagnetic field structure I8, but it is, however, more sensitive and thus adapted to respond to a lower overload current value than that at which the operating armature 20 will respond. The auxiliary armature 29 is pivotally mounted on the same axis as the operating armature 20 and it is here shown as having an upstanding projection 30 that is adapted to engage with an ofiset arm 3| carried by a bell crank lever 32. Mounted upon the end of the lever 32 there is a moveable contact 33 that is. connectedby a flexible conductor 36 to one of the terminals of the operating coil l9 and arranged in cooperating relation with the moveable contact 33 there is a stationary contact 35 which is, connected, as is more clearly shown in Figure 3, through the resistance unit 28 to the other terminal of the energizing coil l9.. The bell crank lever 32 is also biased to hold the

contacts

33 and 35 in engagement with each other independently of the auxiliary armature 29 by means of a coiled spring 36. In this arrangement it is possible to adjust the position and response of the auxiliary armature 2% so as to obtain close critical response to an overload condition upon the circuit breaker. The response of the auxiliary armature 29 is adapted to be regulated by changing the tension of a tension spring 36 by which it is biased against the action of the electromagnetic field structure when energized by the coil I9. The

spring to is here shown as connected at its outer end to a threaded support 31 which may be adjusted to produce any desired tension upon the auxiliary armature 29.

The advantages and mode of operation of the invention may best be described with further reference to Figure 3 of the drawing which shows the complete circuit of the circuit breaker. As here drawn the terminal bushings l8 and H are represented by heavy line conductors which as" is well understood extend. upwardly through the bushings to the line terminals at the-upper ends thereof. When the circuit breaker is in its closed circuit position with the movable contact 22 in engagement with the stationary terminal at the lower end of the bushing Ill as here shown the operating armature 20 and the auxiliary armature 26 will be in their inactive positions and the lever 32 will be held with its moveable contact 33 in engagement with the stationary contact 35 and complete the shunt circuit through the low resistance unit 28. Under these conditions it will be seen that as current flows between the terminals of the circuit breaker the total current will divide between the two parallel paths, one of which includes the low resistance unit 28 and the other of which comprises the electromagnetic field energizing coil I9. Therefore, by properly relating the resistance and impedance of these two parallel paths in the circuit breaker it will be possible to obtain any desired degree of magnetic' force for actuating the operating armature 20 by the use of finer wire and a greater number of turns in coil 19 without at the same time increasing the losses due to such a change. The auxiliary armature 29 may also be rendered more responsive in this manner. Upon an overload or fault the auxiliary armature 29 will operate to open the circuit through the resistance unit 28 and as a result all of the current will temporarily pass through the energizing coil I9 and be available to energize the magnetic field structure l8. This will result in a more powerful attractive force upon the operating armature 20. During the period between the opening and reclosing of the circuit the timing mechanism 21 will come into operation and delay the reclosing of the circuit breaker for a period sufilcient to permit the auxiliary armature 29 to return to its normal position and thus reestablish the circuit through. the low resistance unit 28. Then should the fault or overload be still existent upon the power line, this circuit opening and reclosing operation will be repeated until the fault or overload is removed, or the operating mechanism is locked in its open circuit position as is well understood in the art.

From the above it will be seen that in addition to providing a simple arrangement by which the construction, control and operation of a reclosing circuit breaker may be greatly simplified, the invention also has the advantage that by the use of a low resistance shunt circuit as here proposed, the voltage drop across the operating coil I9 is greatly reduced and therefore the total power loss due to the magnetic control and operating mechanism is reduced to a minimum. At the same time the operating coil I9 may be wound with a larger number of turns to thus increase its magnetizing force with only a slight additional loss due to the increased impedance of the coil. Under normal operating conditions it is contemplated that only about one-ninth of the line current will pass through the energizing coil l9 and therefore the danger of coil burn outs and the need for thermal cut-outs or carefully balanced coils is eliminated. At the same time, the size of the wire forming the coil [9 may be consider ably smaller than would be the case if the coil l9 were required to operate without the shunting resistance 23. When compared with a conventional relay and series coil type of control it will be seen that the present arrangement has the advantage that it can be tested for tripping con-. ditions with facilities usually available at the factory, whereas the corresponding adjustments in a relay type of control would require the establishment of simulated power line conditions both with respect tovoltag'e and current. Toagain compare the present invention with its one :energizing coil 18 operating inconjunction with the two

armatures

20 and 29, as here disclosed, with a-separate relay type of control, it will be seen that in the latter system any change in the rating of the circuit breaker would require a change of both a relay coil and an operating coil, whereas in the present instance such a change in rating would merely require a change in the one coil l9 and the resistor 28 which is a comparatively easy change to make. The present invention also has the advantage that response of the auxiliary armature is more susceptible to accurate adjustment than would be the case with separate relay in which the forces involved are relatively small. Another advantage possessed by the present invention is that when the auxiliary armature 29 is operated to open the shunt circuit it will move into close contact with the poles of the electromagnetic field structure [8 and thus act as a magnetic shunt that will reduce any slam of the operating armature such as would occur in the event of an excessively heavy overload.

While I have, for the sake of clearness and in order to disclose the invention so that the same can be readily understood, described and illustrated specific forms and arrangements, it is to be understood that the invention is not limited to the specific forms disclosed, but may be embodied in other forms that will suggest themselves to persons skilled in the art. It is believed that this invention is new and it is desired to claim it so that all such changes as come within the scope of the appended claims are to be considered as part of this invention.

Having thus describedmy invention, what I claim and desire to secure by Letters Patent is:

1. In a combined control and operating unit for'reclosing circuit breakers ;of the type having an electromagnetic control, the combination of an electromagnetic field structure, an energiaing coil for said field structure connected in series circuit with the line terminals of the circuit breaker, a movable armature associated with and magnetically responsive to said magnetic field structure for controlling the operations of a circuit breaker, a low resistance shunt circuit connected in parallel relation with said energizing coil and also in series with the line terminals of the circuit breaker, said low resistance shunt circuit being adapted and arranged to carry a major portion of the current passing through the circuit breaker under normal operation conditions, and other means also magnetically responsive to said electromagnetic field structure under overload current conditions upon the circuit for opening said low resistance shunt circuit, whereby the full overload current Will pass through said energizing coil under abnormal operating conditions and thus be available to operate said movable armature and control the operation of the circuit breaker.

2. In a combined control and operating unit for circuit breakers of the type having an electromagnetic operated control mechanism, the combination of an electromagnetic field structure, an energizing coil for said field structure connected in series circuit with the line terminals of the circuit breaker, a movable armature associated with and responsive to said magnetic field structure for controlling the operations of a circuit breaker, a low resistance shunt circuit connected in parallel relation with said energizing coil and also in series circuit with the line terminals of the 6. circuit breaker, said low .resistance shunt :circuit being adapted and arranged to carry a :major portion of the current passing through the circuit breaker under normal operation conditions, and a second armature also responsive to said electromagnetic field "structure and operable under overload current conditions upon the circuit,-and a means operated by said second armature for opening said low resistance shunt circuit, whereby the full overload current passing through the circuit breaker will pass through said energizing coil and thus be available to operate said movable armature and control the operation .of the circuit breaker.

3. In a single magnet control and operating mechanism for circuit breakers of the type having an electromagnetic control, the combination of a single electromagnetic field structure, an:energizing coil for said field structure connected in series circuit with 'the'line terminals of the circuit breaker, a main movable armature associated with and responsive to said electromagnetic field structure for controlling the operations of a circuit breaker, a low resistance shunt circuit connected in parallel relation with said energizing coil and to the line terminalsof the circuit breaker, said low resistance shunt circuit being adapted and arranged to carry'a major portion of the current passing through the circuit breaker under normal operation conditions, a normally closed switch in said low resistance shunt circuit, and an auxiliary armature also associated with and responsive to said electromagnetic field structure under overload current conditions upon the circuit adapted and arranged toopen said normally closed switch under predetermined overload conditions, whereby the full overload current passing through the circuit breaker will pass through said energizing coil and thus be available to operate said main movable armature and control the operation of the circuit breaker.

4. In an electromagnetic control and operating unit for automatically operated reclosing circuit breakers of the type having contacts that open upon an overload and then reclose to re-establish the circuit, the combination of an electromagnetic field structure, an energizing coil for said electromagnetic field structure connected in series circuit with the circuit breaker contacts, an operating armature responsive to said magnetic field structure for controlling the opening and reclosing of a circuit breaker when current passing through the circuit breaker reaches a predetermined overload value, a low resistance shunt circuit for bypassing a major portion of the current flowing through the circuit breaker around said energizing coil, a normally closed switch in said low resistance shunt circuit, and an auxiliary armature also responsive to said electromagnetic field structure adapted to operate in response to a predetermined overload current value and open said normally closed switch, whereby the full overload current will pass through said energizing coil and be available to operate said operating armature under overload conditions while under normal current conditions only a small portion of the line current will traverse said energizing coil.

5. In an automatic circuit interrupting and restoring circuit breaker, the combination of an electromagnetic field structure, an energizing coil for said electromagnetic field structure connected in series circuit with the circuit interrupting and restoring contacts of the circuit breaker, a main armature responsive to said electromagnetic field structure adapted when operated to'control the opening of a circuit breaker, said main armature being responsive to said electromagnetic field structure only when said energizing coil is subjected to a predetermined abnormal current value, a low resistance shunt circuit connected in parallel relation with said energizing coil adapted and arranged to shunt a major portion of the current passing through the circuit breaker around said energizing coil under normal operating conditions, a second armature also magnetically responsive to said electromagnetic field structure and calibrated to operate at a predetermined overload current value, and a circuit interrupting switch in said shunt circuit adapted to be opened by an operation of said second armature when the current passing through the circuit breaker reaches said predetermined value, whereby only a fraction of the full line current will pass through said energizing coil under normal operating condition while under abnormal current conditions the full line current will be available for energizing said electromagnetic field structure.

6. A combined relay and operating electromagnet'for controlling the operations of a reclosing circuit breaker, comprising an electromagnet having an energizing coil connected in a series circuit with the current carrying contacts of a circuit breaker, an operating armature responsive to said electromagnet adapted when it operates to open the circuit breaker contacts, a low resistance current conducting shunt connected in parallel circuit with the energizing coil of said electromagnet, a relay armature also responsive to said electromagnet and calibrated to respond to a current value lower than that at which said operating armature will respond, and means operated by a said relay armature for opening the circuit of said low resistant shunt, whereby the full line current will be rendered available. for the operation of said operating armature under abnormal conditions without the coil losses which would occur during normal conditions if said energizing coil were connected in the circuit without said low resistance shunt.

7. In an electromagnetic control and operating unit for electrical apparatus having a series connected operating coil, the combination of an operating mechanism, an electromagnet having an energizing coil connected in series circuit with a current carrying line, an operating armature associated with said electromagnet for controlling the operation of said mechanism, a low resistance shunt connected in parallel circuit with said energizing coil through which a major portion of the current of said line will pass under normal operating conditions, a normally closed switch in the circuit of said low resistance shunt, and a control armature also responsive to said electromagnetic field structure adapted to open said normally closed switch in the event of an abnormal current condition upon said line, whereby the full current of said line will flow through said energizing coil and be available to operate said operating armature under abnormal current cone ditions while only a portion of the line current will flow through said energizing coil under nor mal line current conditions.

CHARLES R. RAY.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS