US2215804A

US2215804A - Circuit interrupting apparatus

Info

Publication number: US2215804A
Application number: US216701A
Authority: US
Inventors: Charles P West
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1938-06-30
Filing date: 1938-06-30
Publication date: 1940-09-24
Anticipated expiration: 1957-09-24

Description

Sept. 24, 1940. c. vP. WEST 2,215,804

CIRCUIT INTERRUPTING APPARATUS Filed June 30, 1938 2 Sheets-Sheetl Phase 74 J77zfter 7/ g Q a3 WITNESSES: INVENTOR w 67707165 1. W552i Sept. 24, 1940. W T 2,215,804

' CIRCUIT INTERRUPTING APPARATUS Filed June 30,' 1938 '2 Sheets-Sheet 2 WITNESSES:

Y INVENTOR- Charles P. West.

Patented Sept. 24, 1M0

more!) s'r rss CIRCUIT INTERRUPTENG APPARATUS Uharles P. West, Forest Hills, LPa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application June 30, 1938Serial No. 216,701

15 Claims.

My invention relates to circuit-interrupting systems and it has particular relation to are interrupting systems utilizing electric discharge apparatus.

It is an object of my invention to provide an arc interrupting system that is not only efficient and reliable, but also inexpensive to manufacture, install and operate.

Another object of my invention is to provide a circuit-interrupting system in which the current fiow shall be diverted before the contacts are sufiiciently opened to produce a substantial arc therebetween.

According to my invention, I provide a system incorporating an electric discharge device provided with a plurality ofprincipal electrodes and a plurality of control or starting electrodes. The discharge device is connected across a set of main contact members of a switching device. The discharge device is of the arc-like discharge type, and its operating characteristic is such that for the proper control potential only a relatively small potential across the principal electrodes is required to initiate a discharge therebetween. The difference in potential between the principal electrodes after a discharge is thus initiated is substantially smaller than the drop in potential across the main contact members of the switching device. Therefore, when a discharge is produced between the principal electrodes, current ceases to iiow through the main contact memhere.

In the practice of my invention, the principal electrodes of the discharge device are connected directly across the main contact members where the arcing is to be eliminated. The starting electrodes are connected to a source of potential havihg a predetermined phase relation with the potential impressed upon the principal electrodes. Control means cooperatively associated with means for actuating the switching device or main contact mechanism are utilized to control the energization of the starting electrodes a predetermined time before the main contacts open.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of spe cific embodiments, when read in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic view showing an embodiment of my invention; and

Figs. 2, 3 and 4 are diagrammatic views showing modifications of my invention.

The apparatus shown in Figure 1 comprises a plurality of supply lines or main conductors ll and it A main line switching device or main 5 contact mechanism i5 is connected in the con ductor ii. The contact mechanism 95 comprises a pair of stationary contact members it, a cooperating movable contact member 39, a spring biased toggle mechanism ii, an electromagnetic tripping mechanism 23 and a trip coil 25. The contact mechanism it may be of any conventional type, as the specific structure shown forms no part of the present invention.

An electric discharge device 211 is connected in w the conductor ll in parallel with the contact mechanism it. The discharge device 2? is preferably of the immersed ignition electrode type and is provided with a pair of mercury pool electrodes 2t and 3!. In the mercury electrodes '29 and suitable starting or

ignition electrodes

33 and 35, respectively, are dipped for providing a cathode spot at the desired time. A transformer 37 having a primary winding 39 andsecondary windings ii and d3 is provided for energizing the

starting electrodes

33 and 35. A rectifier 45 may be provided so that current will flow through starting electrode 33 when the electrode 29 is negative with respect to the electrode 3i. Similarly, a rectifier ll may be provided so that current will flow through starting electrode when electrode ii is negative with respect to electrode 33. The rectifiers i5 and M are shown as disc or oxide film rectiflers, but it will be understood that thermionic or electric'discharge devices may be utilized. The circuit for starting electrode 33 ex- 35 tends from one end of secondary winding 4|, through rectifier 65, starting electrode 33, electrode 29 to the other end of secondary winding 4 I. The circuit for starting electrode 35 extends from one end of secondary winding it through the rectifier ii, starting electrode 35, electrode 3| to the other end of secondary winding 63.

To control theenergization of the transformer 3'! and thus the starting electrodes 29 and 3i, an electro-magnetic device 49 having a set of contact members 5i and an operating coil 531s provided. The circuit for the primary winding 39 extends from main conductor it through the contacts 5|, primary winding 39 to the main conductor I3. 50 However, it will be understood that the primary winding 39 may be energized from any suitable source of electrical energy having the proper phase relation to the main conductors H and l3.

A current transformer 55, the primary winding thereof being indicated as conductor II, is connected in series with the main contact mechanism I5 and in parallel with the discharge device 21. A secondary winding 51 of current transformer 55 is adapted to energize operating coil 53 and trip coil 25 in relation to the current flowing through the contact members I1 and I9 of the main contact mechanism I5. The operating coil 53 is selected so it will actuate electromagnetic device 49 when the current flowing through the contact mechanism I5 is slightly less than that required to cause trip coil 25 to actuate the tripping mechanism 23.

The operation of the above-described apparatus may be set forth as follows: Assume that the contact mechanism I5 is in the closed-circuit position with the movable member I9 in engagement with the stationary contact members I1 and that normal current traverses the conductor II, contact members I1 and I9 and conductor I3. When an overload or short-circuit occurs, the current through the primary winding of current transformer 55 and the contact members I1 and I9 increases, thus increasing the current through operating coil 53 and trip coil 25. When the current increases to a first predetermined value, the operating coil 53 actuates the electromagnetic device 49 to close contacts 5 I, thereby energizing the primary winding 39 of transformer 31. Current is now transmitted from secondary winding 4I through starting electrode 33 to form a cathode spot on mercury electrode 29. Similarly, current transmitted from secondary winding 43 through starting electrodes 35 forms a cathode spot on mercury electrode 3|. Current does not flow through the discharge device 21 when the contact mechanism I5 is closed, because the electrodes 29 and 3| are at substantially the same potential.

When the current through current transformer 55 reaches a second predetermined value, slightly higher than the first predetermined value, thetrip coil 25 actuates the trippingmechanism 23, thus causing the main contact mechanism to open. The

coils

53 and 25 may be energized substantially simultaneously if the inertias of the moving parts of the electromagnetic device 49 and the contact mechanism I5 are such that the transformer 31 is energized before the main contact members begin to open. When the contact members I1 and I9 separate a short distance, the difference in potential increases between the electrodes 29 and 3| by reason of the increase in the contact resistance and the discharge device 21 becomes energized. The contact resistance is substantial before the contacts are entirely separated and, therefore, the discharge device becomes conductive before an arc is produced between the contacts. The current in conductor I I is then shunted around the current transformer 55 and the contact-members I1 and I9 through the discharge device 21. When the discharge device becomes energized, the magnitude of the potential drop between the electrodes 29 and 3| and, therefore, between contact members I1 and I9 is such that the current flow can no longer be maintained through the contact members I1 and I9. Current transformer 55 then becomes deenergized, and thus the operating coil 53 and trip coil 25 become deenergized. Upon deenergization of operating coil 53, electromagnetic device 49 is actuated to open contacts 5|, thereby deenergizing the. starting

electrodes

33 and 35. Current in conductor I I continues to flow through discharge device 21 until the end of the half cycle of the alternating current. The discharge device thus becomes deenergized, and is not reignited in the succeeding half cycles because the

starting electrodes

33 and 35 are deenergized.

In Fig. 2, a pair of electric discharge devices 59 and GI, each having an anode 53, a cathode 35 and a starting electrode 61 are connected in parallel to" the main contact mechanism I5. Gridcontrolled gaseous devices and other arc-like discharge devices may be utilized in place of the discharge devices 59 and 6|. The discharge devices ,59 and 6| are connected in anti-parallel so that the anode-cathode polarity of one of them always corresponds to the polarity of the alternating current in conductor l I. The starting electrodes 61 of discharge devices 59 and GI are energized from transformers 69 and H, respectively. The transformers may be energized from a circuit supplied by a feeder or control transformer 13 through a phase shifter 14. The potential impressed upon the starting electrode 61 may be dephased by phase shifter 14 so that it reaches a positive value of substantial magnitude at the beginning of each positive half cycle of potential impressed upon the main electrode 63. The operation of the system is similar to that hereinabove described with reference to Fig. 1. When the potential across the main contact mechanism increases, the discharged device forwhich the anode-cathode potential is of proper polarity is immediately energized and then the circuit is completely interrupted.

As is apparent from Fig. 2, the circuit may be opened if only one of the discharge devices 59 and BI is utilized. If this is desirable, the discharge device 5|, transformer H and rectifier 41 may be omitted.

In Fig. 3, a transformer 15, having a primary winding 11 and a single secondary winding 19, is utilized to energize both of the starting

electrodes

33 and 35. An additional set of contacts H on electromagnetic device 49 is provided to control the energization of the starting

electrodes

33 and 35. A current limiting resistor 33 may also be provided. The circuit for the starting

electrodes

33 and 35 extends from one side of secondary winding 19 through resistor 83, starting electrode 35, electrode 3I, conductor II, contact members I1 and I9, conductor II, electrode 29, starting electrode 33, contacts 8| to the other side of secondary winding 19. The operation of the system is similar to that hereinabove described with reference to Fig. 1. When the main contact mechanism I5 is opened, the potential across the contact members I1 and I9 is also impressed upon the starting electrode circuit through the electrodes 29 and 3 I. To deenergize the discharge device 21 after the contact mechanism I5 has been opened, the starting electrode circuit is opened when electromagnetic device 49 is actuated to open contacts 8 I.

It will readily be understood that the actuation of main contact mechanism I5 may be initiated by means other than the current responsive means hereinabove described. In Fig. 4, the energization of operating coil 53 and trip coil 25 is mitiated by completing the circuit through a set of contacts 85. The contacts may be cooperatively associated with a manually operable device, such as a push buttoncr knife switch, or with an electromagnetic device actuated in response to predetermined circuit conditions. A pair of

conductors

81 and 89, energized from a source of electrical energy (not shown) are utilized for energizing the

coils

53 and 25. When contact membars 85 are closed, operating coil 53 becomes energized through a circuit which extends from conductor 81 through contacts 85, operating coil 53, resistor 9| to conductor 89. The device 452 is actuated to close a plurality of contacts 5|, to energize the starting

electrodes

33 and 35 from

batteries

93 and 95, respectively, or any other suitable source of unidirectional current. Contacts 91 are closed to establish a holding circuit for the operating coil 53. Contact members 99 are also closed to energize trip coil 25 to cause the actuation of contact mechanism I5. The discharge device 21 becomes energized and the current in conductor II is shunted around contact members I1 and I9 through the device 21 as hereinabove described. A set of contacts l0] actuated by con tact mechanism l5 are utilized to deenergize operating coil 53 when the contact members 11 and [9 are opened. The starting

electrodes

33 and 35 are then deenergized by the opening of contacts 5| and the discharge device 21 becomes deenergized at the end of the half cycle of the alternat-' ing current.

I do not wish to be restricted to the specific structural details, arrangement of parts or circuit connections herein set forth as various other modifications thereof may be effected without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A circuit-interrupting system comprising a main contact mechanism, an electric discharge device connected in parallel with the said contact mechanism, the said device having two main electrodes and a starting electrode associated with each main electrode, and means responsive to a predetermined current through the said contact mechanism for energizing at least one of the said starting electrodes a predetermined time before the said contact mechanism is actuated.

2. A circuit-interrupting system comprising a main contact mechanism, an electric discharge device connected in parallel with the said contact mechanism, the said device having two main electrodes and a starting electrode associated with each main electrode, and means responsive to a predetermined current through the said contact main electrode, and means responsive to a predetermined current through the said contact members for alternately energizing said startingelectrodes a predetermined time before the said contact mechanism is actuated.

4. A circuit-interrupting system comprising a main contact mechanism, an electric discharge device connected in parallel with the said contact mechanism, the said device having two main electrodes and a starting-electrode associated with each main electrode, and means for energizing at least one of the said starting-electrodes a predetermined time before the said contact mechanism is actuated.

5. A circuit-interrupting system comprising a main contact mechanism, a pair of separate electric discharge devices connected in anti-parallel across the contact mechanism, each ofsaid devices having a plurality of principal electrodes and an ignition-electrode cooperatively associated with one of the said principal electrodes, and means responsive to a predetermined current through the said contact mechanism for energizing the said ignition electrodes a predetermined time before the said contact mechanism is actuated. e

6. A circuit-interrupting system comprising a main contact mechanism, an electric discharge device connected in parallel with the said contact mechanism, the said device having a plurality of principal electrodes and a starting electrode 00- operatively associated with one of the said principal electrodes, and means for energizing the said ignition electrode before the said contact mechanism is actuated.

7. In, a circuit-interrupting system for an electrical circuit comprising a main contact mechanism connected in parallel with an electric discharge device having a starting electrode and a plurality of principal electrodes, means for actuating the said contact mechanism, and starting means cooperatively associated with the said actuating means for impressing a potential between the said starting electrode and one of the said principal electrodes before the said contact mechanism is actuated.

8. In a circuit-interrupting system for an electrical circuit comprising a main contact mechanism connected in parallel with an electric discharge device having a starting electrode and a plurality of principal electrodes, means for actuating the said main contact mechanism, starting means cooperatively associated with the said actuating means for impressing a potential beand a control electrode, and means for energizing the said control electrodes before the contact mechanism is actuated.

10. A circuit interrupting system comprising a main contact mechanism, a pair of separate electric discharge devices connected in anti-parallel across the said contact mechanism, each of said devices having a plurality of principal electrodes and a control electrode, means for actuating the said contact mechanism, means associated with the said actuating means for impressing a potential between the control electrode and one of the said principal electrodes of each of said discharge devices before the said contact mecha-' nism is actuated, and means for deenergizing the said discharge devices, after the said contact mechanism has been actuated.

11. A circuit-interrupting system comprising a main contact mechanism, an electric discharge device connected in parallel with the said ,contact mechanism, the said device having two main electrodes and a control electrode associated with each main electrode, and means responsive to a predetermined circuit condition for energizing the said control electrodes before the said contact mechanism is actuated.

12. For use in opening a circuit, the combination comprising mechanical contacts in said circuit for opening said circuit, normally non-conductive electric discharge valve means bridging said contacts, means for opening said contacts, the said valve means having control electrode means which is energized sufliciently to render the valve means conductive in response to the excitation of said opening means prior to the actuation of said contacts by said opening means, and means cooperative with said contacts as they are opening for rendering said valve means conductive before an arc is formed between said contacts.

13. A circuit'interrupting system comprising a main contact mechanism, an electric discharge device of the immersed-ignition-electrode type connected in parallel with the said contact mechanism, the said device having a plurality of principal electrodes and a starting electrode cooperatively associated with each of said principal electrodes, and means for energizing at least one of said starting electrodes before the said contact mechanism is actuated.

14. A circuit interrupting system comprising a main contact mechanism, a pair of separate elec tric discharge devices of the immersed-ignitionelectrode type connected in anti-parallel across the said contact mechanism, each of said devices having an anode, a cathode of the mercury type, and an ignition electrode immersed in said cathode, a rectifier connected to each of said ignition electrodes, means for actuating said contact mechanism, means including a transformer associated with said actuating means for impressing a potential through said rectifier between said starting electrode and said cathode of each of said discharge devices before the contact mechaelectrodes, means for actuating said contact mechanism, means for energizing said discharge devices, said energizing means including a transformer associated with said actuating means for impressing a potential through said rectifier between said starting electrode and said cathode of each of said discharge devices before the contact mechanism is actuated, and means for deenergizing said discharge devices, after said contact mechanism has been actuated.

' CHARLES P. WEST.