US1724840A

US1724840A - Circuit maker and interrupter

Info

Publication number: US1724840A
Application number: US97734A
Authority: US
Inventors: Benjamin W Jones; Charles H Chapman
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1926-03-26
Filing date: 1926-03-26
Publication date: 1929-08-13
Anticipated expiration: 1946-08-13
Also published as: FR630059A; BE340864A; GB268329A

Description

1929- B. w. JONES ET AL 1,724,840

cmcun MAKER AND mrnxnur'rn Filed March '26, 1926 Inventors: Ben'aminW. Jones, Chem-lea H. Chaqom 2.0m

Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

BENJAMIN W. JONES, F SCHENECTADY, AND CHARLES H. CHAPMAN, OI SCOTIL,

new max, new YORK.

.ASSIGNORS TO GENERAL ELECTRIC COMPANY, A. CORPORATION OI CIRCUIT MAKER AN'D INTEBBUPTEB.

Application filed March 28, 1928. Serial No. 97,734.

Our invention relates to improvements in circuit makers and interrupters, and in particular. to circuit closers and 'interrupters of the well known contactor type.

One of the difficulties experienced with contactors is that of the welding of the contacts thereof. As a result of investigations -which we have made, we have found that one of the common causes of this welding action is the automatic opening and reclosing of the resiliently engaging circuit interrupting contacts due to the repulsive effect of the current through the contacts. For all ordinary values of current which the contactor is called upon to interrupt, the repulsive effect is not of so great a value as to produce a bad effect but for large currents the repulsive efi ect is appreciable. When the large value of currents starts through the contacts which are held together by a certain spring pressure the magnetic force of the current throws the contact tips apart and causes an arc to be established at the contact tips. Magnetic blow out devices are ordinarily provided for efiecting the interruption of the arcs established at the circuit interrupting contacts, and these blow out devices are usually provided with an arcing horn or a pluralit of arcing horns. The

' so large current throug the contacts causes a ve hea magnetlc field to be set up'by thymagn t ic blow out device and this field will cause the are established at the contact tips to be extended toward the arcing born or horns. This action diverts the current from the contact tips and effects a reduction of the current therethrough. The repulsive force on the contacts is thus reduced and the contact tips reclose so that the our- 40 rent is permitted to take the original path and increase in value. Since the contact tips are hot from the effects of the arc and the-current through the tips, when the tips reclose they are likel to be welded and 46 remain closed even t ough the operatin magnet or .-other o pgrating and holding device is released. e above action is very rapid and may occur several times before the operating .and holding device is fully 50 released. Therefore, if the circuit interrupter is provided with a'magnetic blow out effective to interrupt a large amount of ower, the interrupter may be rendered ine ective by reason of the welding action of the contact tips.

The object of our invention is to prevent the above mentioned welding action of the contact tips. In carr 'ng our invention into effect in a form WhlCh we now re ard as a preferred form thereof, we cause 516 contact tips to be latched in their separated positions when the tips are thrown apart by the above mentioned repulsive action so that the tips can not automaticall reclose to be welded shut. The latching evice is preferably arranged so as to require the manual release thereof and this must be done before the 'contactor is rendered effective to again close its controlled circuit. The latching device is never efi'ective for the ordinary values of current through the contacts and only becomes effective for the large values of ipurrent which would cause the welding acion.

For a better understanding of the inveution, reference is had to the accompanyin drawing, in which Fig. 1 is a side view 0% an open contactor in accordanw with the invention; Fig. 2 is a detail showing the relative position of various arts when the contact tips are closed, an Fig. 3 is another detail similar to Fig. 2 showing the position of the s ring ressed movable contact when the la g evice has operated by reason of the separation of the contacts due to the above mentioned repulsive action.

Referring to the drawings, the circuit maker and interrupter is indicated as of the well known contactor type having a stationary contact 10 with which the movable contact 11 is arranged to make abutting en 0- ment for completing the circuit throug the contacts. The movable contact 11 is mounted on a pivotally mounted support 12 which 1s reslliently held in position with respect to the pivotally mounted magnetic movable member or armature -13 by means of the g spring 14, which is interposed between the member 12 and the upper end of the armature 13. It will be observed by reference to Figs. 1 and 2 that a slight relative movement .occurs between the support-. 12 and the armature 13 when the contacts move into abutting engagement, whereby the contacts move into engagement with a wiping action. The armature 13 forms a part of an operating electrotends to len magnet having the winding spool 15 mounted on the core 16 of magnetic material, these parts being suitably mounted in the support 17 of magnetic material.

A magnetic blow out device is provided for interrupting the arcs formed between the contact tips 10 and 11. This blow out device comprises a coil 18 which is included in the circuit through the contact tips 10 and 11, and an arc chute 19 of refractory material held between suitable pole pieces 20 secured to the core 21 of the blow out device. The parts of the switch are mounted on a suitable. insulating support or base 22. The arrangement thus far described is a well .known type of contactor.

The current through the contact tips 10 and 11 sets up a magnetic force which tends to separate its tips. For the ordinary values of current which the contactor is called upon to handle, this magnetic force is insufiicient to overcome the holding closed eifect applied by the armature 13 through the spring 14. However, in case the current throng the switch contacts isvery materially largerv than the ordinary values encountered, as

instance a value such as would be experienced under short-circuit conditions, the repulsive effect on the contacts is increased to such a value that the strain on the sprin 14 is insufiicient to hold the contacts in t eir closed ositions. This will eifect a se aration 0 the contacts and an arc w' be formed at the contacts By reason of the.

fact that there is a very powerful magnetic field set up by the blow out device which hen the are thus formed and to extinguish e same, the arc will shift from .the contact 10 to the arcing horn 23. This will effect a reduction in thecurrentthrou h the contact tips, particularly through e contact 10' and the repulsive effect is thus very materially reduced. The contacts will then reclose and because of the fact that they are hot from the effect of the are which had been previously established and the current through the contacts, the reclosing of the contacts will likely effect the welding there:

of. The contacts will'then remain closed from the contact 11. The detent 24 is mounted for a sliding motion in the support 26,

and the spring 27 is provided for biasing the detent into engagement with the projecting end 25. In Fig. 1 we have indicated the rela tive positions of the various parts when the o5 contactor is in-the open position. In Fig. 2 we have indicated the position these parts assume when the electromagnet is energized, the armature 13 attracted and the contacts 10 and 11 brought into a'circuit closing engage- 70.

by the detent-in such a way that the detent will prevent the return of the contact 11 to its position indicated in Fig. 1 when the win ing of the electromagnet is deenergized and the switch contacts opened. If the current through the switch contacts is of such a value that the repulsive efiect will separate the movable contact 11 from the stationary contact 10 an appreciable distance so that the projecting end 25 will slide over the edge of the detent 24, as indicated in Fig.

3, the contact 11 will thus be prevented from returning into engagement with the contact 10. It will thus be seen that even though the winding of the electroma et is energized to reclose the contacts, t ese contacts will not be closed. When the detent 24 thus operates to prevent the reclosure'of the contacts, it is'necessar to manually release the detent, this being one by pressing down on the'button 28 which is secured to the detent 24.

The separation of the contacts due to the. repulsive effect mentioned may occur when the windin of the electroma et is deenergized to efi ectthe opening 0 the contactor efore the armature is fully released. In such a condition, the detent 24 will prevent tllle reeosing of the contacts and the welding t ereo What we claim as new and desire to'secure by Letters Patent of the United States is:

1. A circu1t maker and interrupter having a pair of circuit interrupting engaging contacts, resilient means for holding the contacts in engagement, and a normally inactive device w ich becomes effective to hold the contacts in their separated position-when the contacts are separated a predetermined distance due to the repulsive efiect of;.-the current through the contacts.

2. A circuit maker and interrupter having a pair of circuit interrupting, engaging contacts, a resilient support for one of said contacts, and means for preventing the reclosure of said contacts when the contacts separate due to the repulsive efi'ect of the current through the contacts.

3. A circuit maker and interru ter having a stationary contact and a movab e cooperating contact arranged to engage therewith, I

and a device rendered operative by a predetermined movement of said movable contact away from said stationary contact due to the repulsive effect of the current through the contacts for preventing the reclosure of the contacts after such movement.

4. A circuit maker and interrupter having duction of the current through the contacts effected by said blowout.

5. A circuit maker and interrupter having a pair of circuit interrupting engaging con tacts, aresilient support for one of said contacts, means for holding said contacts in engagement, and means for preventing the automatic'reclosure of said contacts after the separation thereof due to the repulsive effect of the current through the contacts when said holding means is released.

6. A circuit maker and interrupter having a pair of circuit interrupting engaging contacts, a resilient support for one of said contacts, an operating member for effecting the closure'of the contacts and for holding the same in circuit closing engagement, and means for preventing the reclosure of said contacts, after the separation thereof due to the repulsive effect of the current through the contacts, when the holding effect of said operating member is released.

7. A circuit maker and interrupter having a pair of relatively movable abutting contacts, a resilient support for one of said contacts for providing a resilient wiping abutting circuit comfpleting engagement of the contacts, means or holding said contacts in engagement, and means for preventing the automatic reclosure of said contacts after the separation thereof due to the repulsive effect of the current through the contacts.

8. A contactor having a stationary contact, a movable contact arranged to engage therewith, aresilient support for said movable contact, a magnetic movable member for operating the said support and movable contact, an electromagnet for operating said member, a magnetic blowout for the said contacts, and a resilient latch cooperating with said movable contact for preventing the same from returning to the closed position when separated from the stationary contact by the repulsive efiect of the current through the contacts.

9. A contactor having a stationary contact, a movable contact arranged'to engage therewith, a resilient support for said movable contact, a magnetic movable member for operating the said support and movable contact, an electromagnet operable when energized to hold said contacts in engagement and means for preventing the reclosure of said contacts by the operation of said electromagnet after the se aration thereof due to the repulsive effect 0 the current through the contacts.

In witness whereof, we have hereunto set our hands this 24th day of March, 1926. BENJAMIN W. JONES.- CHARLES H. CHAPMAN.