US2678361A - Electrical interrupter - Google Patents

Description

May 11, 1954 F. MITCHELL ELECTRICAL INTERRUPTER 5 Sheets-Sheet 1 Filed Jan. 3, 1952 y 1, 1954 F. MITCHELL I 2,678,361

ELECTRICAL INTERRUPTER Filed Jan. 3, 1952 5 Sheets-Sheet 2 3 MW @{LJ 43.

Patented May Il, 1954 2,678,361 ELECTRICAL INTERRUPTER Frank Mitchell, Adelaide, South Australia, Australia Application January 3, 1952, Serial No. 264,745

Claims priority, application Australia March 29, 1951 9 Claims. (01. 200-106) This invention relates to an improved electrical interrupter.

Interrupters and circuit breakers of many types have been proposed heretofore some of which were in the nature of a fuse which was blown when the safe current value was exceeded and some of which were in the nature of a switching mechanism actuated by a fault, overload or other condition, the former type also including the cartridge type of fuse in which the arc is extinguished by a suitable surrounding liquid or solid medium.

In the beforementioned cartridge type of fuse the interruption of the current is achieved by a fusible element both for the liquid and the solid material are extinguishing types. This factor limits the use of the cartridge to a specified minimum current so that some faults will not be sufficient to actuate the fuse. The fuse is not usually operated except by melting the fusible element.

It is therefore the principal object of this invention to provide a cartridge type of interrupter with mechanical actuation initiated from any type of fault on the system.

In the previously known forms of fuses or interrupters certain difficulties have existed in breaking the circuit in a safe manner which ensures that the equipment protected by the fuse or interrupter suffers a minimum of damage and it has also been a problem to effectively operate on multi-phase circuits of high operating voltages and currents unless relatively expensive equipment was used.

In order to prevent unbalanced voltages from being impressed on multi-phase consuming apparatus it is desirable with multi-phase systems to interrupt all phases and a further object of this invention is to interrupt all the phases practically simultaneously if a fault or overload occurs on one or more phases.

A still further object of this invention is to provide a relatively simple interrupter which, though it may be used on single-phase installations, it particularly is appropriate for interrupting supply to multi-phase equipment, this object being achieved by interposing the current-interrupting member or members between insulators one at least of which is movable under suitable control to effect the interruption.

In the case of multi-phase circuits the interrupting cartridges in all phases have their action initiated by suitably coupling the movable insulators to effect the desired simultaneous interr ruption.

In accordance with this invention the improved electrical interrupter consists of a plurality of insulators and a support for the insulators to allow relative movement between them. A cartridge which normally carries the current but which may interrupt same is positioned between the insulators and is actuated to interrupt when relative movement occurs between the insulators. A control is provided to initiate the insulator movement.

The cartridge may comprise loaded contacts locked by a withdrawable pin disposed to be displaced when movement occurs between insulators to allow the loaded contacts to part.

Relative movement between the insulators may take a number of forms and may be effected in various Ways and while one insulator may be fixed, the other insulator when released may be permitted to fall through a short distance. In the form illustrated the moving insulator is hinged and it is supported by an operating arm, and a trigger release is provided for the operating arm so that an electrically operated trip coil may release the operating arm to give the movement between the insulators.

The cartridges used comprise mechanical current-interrupting means disposed in arc extinguishing means, the current-carrying means of the cartridge being mechanically opened when a force is applied between the ends by relative movement between insulators. Throughout this specification the term cartridge is to be given this meaning.

Where the interrupter in accordance with this invention is applied to a multi-phase system each phase has a pair of insulators and the movement between the insulators in each phase is so utilised that it will actuate the cartridges in all phases simultaneously. To give the required simultaneous actuation of a cartridge in each phase, the one insulator may be fixed for each phase and a hinged insulator provided for each phase. The hinged insulators may be coupled together by a shaft which is prevented from turning by an operating arm restrained by a catch which in turn is operated from an electri cally operated trip coil which initiates the movement between the insulators in each phase simultaneously.

In order, however, that the invention may be more clearly understood it will now be described with reference to the accompanying drawings in which:

Fig. 1 illustrates a front elevation of a threephase interrupter in accordance with this init vention in which the operating parts for the interrupter on one phase include the insulators and the cartridge but the insulators and cartridges have been removed from the operating sections of the other to illustrate the operation of the device.

2 is a side elevational section on line 2-2 of Fig. l and showing the insulators and cartridge in position upon the operating section of the unit.

Fig. 3 is a section as on line Fl -3 of l and illustrates the operating rods for both resetting the mechanism and earthing the terminals.

Fig. t is an enlarged sectional side elevation with the insulators partially broken away illustrating the actuating mechanism for the interrupter.

Fig. 5 is a central sectional elevation illustrating one type of cartridge which may be used in accordance with this invention, and

Fig. 6 is a partial central sectional elevation illustrating a further form of cartridge which may be used in accordance with this invention.

The drawings illustrate a three-phase system incorporating the interrupter but it will be appreciated that the invention may be applied to other inulti-phase systems or to a single phase line in a slightly modified form.

The three phases have supports t, 5 and ii at the lower end of which are the fixed lower sulators l which extend outwardl substantially horizontally with a terminal contact 8 at their outer end to which may be connected the line to ie interrupted.

The central support 5 has secured to it a mechanism box it having at its forward end bearings for a phase coupling shaft i l which extends transversely across the supports a, 5 and 8. The ends of the shaft ii turn in bearings upon the supports 4 and ii. Linked with the shaft H are the movable insulator supports I2 which each have an upwardly extending arm or bracket i l the upper end id of which is movable along a shaft 56 secured to each of the supports 4, 5 and 6. Each shaft It has at its forward end a stop I! and a spring I8 is positioned between the upper end ill of the arm I i the stop H. The downward movement of each upper movable insulator H) which is secured upon the movable insulator support 12 is therefore opposed by the action of the spring it which forms buifer means and a limiting device for the downward movement of the insulators it when. they turn with the phase coupling shaft II.

The control for the movement between the fixed insulators l and the movable insulators IQ for each phase is provided from the insulator release box it which is carried upon the central support 5. Carried upon the under side of the mechanism box H3 is a trip coil 20 having a plunger 2| which is arranged to be moved upwardly when the trip coil 26 is energised. A trig-- ger 22 is pivoted at 23 to an operating arm 27 and has a catch 25 adapted to restrain a reset arm 26 pivoted at the rear of the mechanism box Ill. The reset arm '26 is positioned above the operating arm 2"! which supports the central movable insulator support !2 by means of an adjustable stop 28. The outer pair of movable insulator supports I 2 is coupled to the central support [2 by the shaft II. The trigger 22 is disposed in the path of the plunger 2i and the catch 25 normally holds the reset arm 26 in position and therefore restrains the operating arm 2'! which thereby supports the weight of the movable insulators It by means of the phase-coupling shaft ii. If a fault or an overload occurs in the system a detecting relay energises the trip coil which will actuate the plunger 21 which will move upwardly and operate the trigger 22 which in turn releases the catch 25 then the reset arm 26 and the operating arm 2? so that the insulators i9 may turn downwardly when the phase-coupling shaft ll rotates, it being appreciated that the three insulators IS will move downwardly simultaneously.

In. order to reset the catch 25 (as particularly illustrated in Fig. 3) the shaft 3!! upon which the reset arm 26 is secured has a lever arm 3| secured to it outside the mechanism box 10 and the free end of the lever arm M is coupled to a slotted clevis 32 secured upon the end of a reset rod 34.

To reset the unit after the plunger '21 has returned to its normal position the reset rod 34 is simply moved downwardly which rotates the lever arm 3! and turns the shaft 3B which in turn will move the reset arm 26 downwardly to reset the catch 25 and move the operating arm 2'! into its normal position so that the movable insulators l9 will then be lifted upwardly by the shaft ii in readiness for another tripping operation. The reset rod 34' must be returned to its upper limit in the slotted clevis 32 after the resetting operation.

For each phase the movable insulator is has an upper contact 36 incorporating an actuating head 31 and an actuating pin 38. Carried b tween the actuating head 37 and the lower terminal contact 8 for each phase is the current-interrupting cartridge 39, the cartridges being easily removable for replacement or renewal after the device has been actuated to interrupt the circuit.

The type of current-interrupting cartridge 39 which may be used can be varied according to re quirements but the cartridge particularly illustrated in 5 is of the type having liquid arc extinguishing means and may be actuated from the actuating pin 38 on the actuating head ti.

The lower end of the current interrupting cartridge 39 for each phase is connected to the lower terminal contact 8 by a releasable clamp 40 while the top of the cartridge is connected to the actuating head 37 by means of the releasable clamp 4!. The releasable clamp 41 is coupled to the actuating head 3'! by means of a clamping extension 42 and the link 43' so that the top or the cartridge 39 is held but will allow downward movement of the insulator IS. The releasable clamp ll is electrically connected to the upper contact 3i) by means of a braided connection.

The actuating pin 38 on the head 37 is normally retained above the surface of the top of the current-interrupting cartridge 39 but when the movable insulator I9 is displaced downwardly when released by the trip coil 20 the actuating pin 38 moves downwardly and strike a frangible disc 44 positioned in the top of the current-interrupting cartridge 39.

With particular reference to Fig. 5a liquid type of current-interrupting cartridge is illustrated having an upper cap 45 and a lower cap ll; which are adapted to be carried by the releasable clamps 4i and 40 respectively. Carried between the caps 45 and 46 is the insulating tube 4? of glass. Disposed within the cap 45 of the cartridge is an annular contact 48 which co-operates with a withdrawable contact 49 which is conical in form so that it give a line contact between it and the annular contact 48, The withdrawable contact 49 is itself spring-loaded to give the required pressure between the contacts to carry the current, the spring 56 being disposed within the tube 41. The conical end of the withdrawable contact i9 is split at 5| and so shaped that this end can collapse inwardly when a holding pin 52 is displaced from same. The angle of the cone is selected to allow the spring 50 to exert the required contacting force and also allow quick withdrawal of the contact 49 from the fixed annular contact d8 when the holding pin 52 is displaced out of its locking position within the split portion of the withdrawable contact Q9.

The holding pin 52 has its lower end enlarged in section and is positioned within a reduced diameter section of the withdrawable contact Mi but the other end of the holding pin 52 is adjacent the frangible disc 44. It will be seen that with this arrangement using the frangible disc 44 adjacent the holding pin i=2 the cap s5 is sealed at the same time allowing the movement of the pin 52 when the frangible disc 44 is struck by the actuating pin 38.

The tube ill is filled with a suitable arc-extinguishing fluid and the liquid director 53 is provided adjacent the withdrawable contact and in such a position that when the holding pin 52 is displaced and the contact is interrupted under the influence of the spring 50 a direct flow of arcextinguishing fluid is directed to the site of the arc. For this purpose the director 53 has a lower conical face arranged to direct a jet of liquid through the annular space between the inner opening of the member 53 and the periphery of the tube which it encircles.

The withdrawable contact 69 is provided with conducting tails 54 to transmit the current from it to the cap 46 at the lower end or the cartridge.

In actual operation when a fault occurs or it is desired to break the circuit the movable insulators i9 for each phase are released from their locked position so that they fall downwardly to allow the actuating pin 33 to strike the frangible disc 44 so that the holding pins 52 are moved downwardly until the reduced section allows the expanded withdrawable contact 69 to collapse and the spring pressure will cause the split portion of the withdrawable contact $9 to be moved inwardly and displaced from its annular contact 58 so that the circuit is automatically broken. At the same time for each phase it will be appreciated that when the circuit is broken and the arc occurs the arc-extinguishing material will automatically be thrown upwardly through the annular gap between the director 53 and the tube which it encircle to extinguish the arc.

One advantage of using this type of cartridge is that it is easily replaceable and it is only necessary to reload the cartridge to provide a new frangible disc 44 and reseal same before the cartridge may be again replaced between the upper and lower releasable clamps ll and to respectively.

Referring now to Fig. 6 a particular type of cartridge is illustrated which could be used in accordance with this invention and could be applied between the insulator in a similar manner to the cartridge illustrated in Fig. 5. The cartridge has a lower cap 56 and an upper cap between which is the fibre tube 57 carrying the solid arc-extinguishing material 58. The lower cap 55 has an annular contact 68 secured to it which co-operates with a withdrawable contact .8! the end of which is specially shaped and is split so that its end can collapse inwardly when a holding pin 62 is withdrawn from its position in a reduced diameter portion of the withdrawable contact 6 l. The withdrawable contact 6| is coupled to an upper terminal rod 63 which is spring actuated to displace the withdrawable contact 6| from the annular contact 6%. An auxiliary element 64 may be provided in the form of an element or wire which may be blown or broken when the upper terminal rod 53 moves upwardly which initiates the arcextinguishing means for lower current values while for larger current values the actual breaking of the arc between the annular contact 66 and the withdrawable contact 6! will initiate the vapourising of the arc-extinguishing material 58.

It will be seen that the cartridge illustrated in Fig. 6 may be operated in a similar manner to the type illustrated in Fig. 5 and that the holding pin 62 must be actuated by the relative movement between insulator but is normally held at the lower end of the cartridge. Suitable coupling means may be applied from the upper movable insulator 9 to achieve this purpose but it will be appreciated that the lower insulators l for each phase could be movable and the upper insulator i9 could be fixed so that the lower terminal contact 8 could provide the movement to remove the holding pin 62 and actuate the cartridge.

In order to provide earthing of the lower terminal contact 8 and th upper contact 36, after the interrupter has operated, earthing blades 65 and iii are provided for each phase which may be moved on to earthing contacts carried by the contacts 36 and 8 to earth the whole device for removal and replacement of the interrupting cartridge 39.

Although a particular feature of the interrupter is the fact that the control to initiate the insulator movement is in the form of a trip coil, it will be appreciated that the same mechanism could be actuated manually by mechanical tripping of the trigger.

From the foregoing it will be appreciated that an improved electrical interrupter is provided which is characterised by a plurality of insulators at least one of which is movable but is normally held in a fixed position, a self-contained electrical current-carrying cartridge being inserted between the insulators in such a manner that while the insulators are in their locked position the cartridge serves as a current-carrying device but when, because of the operation of a fault detecting relay or other device the one insulator is released to move to a new position such as by falling down under its own weight, means in the cartridge itself are actuated to break the circuit between the insulators although the cartridge will still remain as a bridge between the insulators, but its capacity to carry current will have been removed because the which normally hold the contacts within the cartridge in their current-carrying position will have been actuated to allow the spring means within the cartridge to have drawn the contacts apart and the circuit will thus be broken.

In considering the invention it must be clearly borne in mind that the only insulators used need be the standard types of supporting insulators for switch gear which is being protected, one of which is allowed to move so that the whole of the current-carrying means including the cartridge are fully supported on the two insulators, the movement of the one insulator being only slight as the actual break in the line is effected by a mechanical breaker within the cartridge itself which is merely initiated in its action by the slight movement of the movable insulator.

I am aware that non-movable insulators have prior to this date supported a cartridge in which a break is effected but a the insulators themselves were non-movable it was necessary to carry through. one of the insulators operating means which would have the full operating voltag impressed across it.

I am also aware that insulators have had special breaking means inserted between them which themselves were supported on or by a further movable insulator but in that case an additional insulator was required in which a large movement was necessary so that the gear required of a relatively complicated nature as compared to my present invention. Also the larger movement necessary to effect the separation of the contacts makes high speed operation impossible.

What I claim is:

1. An improved electrical interrupter characterised by a plurality of insulators, a support for the insulators to allow relative movement between the insulators, means to normally hold the insulators in a fixed position, an electrical current-carrying cartridge between the insulators, axially confined on one insulator, guide means between the other end of the cartridge and the other insulator, a trip coil to initiate the insulator movement, a fixed contact in the car tridge, a withdrawable contact also in the car tridge having its one end split and being spring loaded, a holding pin in the split portion of the withdrawable contact, means on the movable insulator to withdraw the pin when relative move ment occurs between insulators, and arc-extiin guishing material in the cartridge.

2. An improved electrical interrupter characterised by a fixed insulator and a hinged insulator carried upon a support to allow movement of the hinged insulator, an operating arm to nor mally support the hinged insulator in a fixed position, a trigger, a catch for the operating arm releasable by the trigger, an electrical currentcarrying cartridge between the insulators axially confined on the fixed insulator, guide means between the other end of the cartridge and the hinged insulator, a pin in the cartridge to main tain the circuit, said pin being displaceable by the said hinged insulator, arc-extinguishing means for the cartridge, and an electrically operated trip coil to operate the trigger release.

3. An improved electrical interrupter for multi-phase systems characterised by a fixed and a movable insulator for each phase, a support upon which the fixed insulator for each phase is carried, a transverse phase-coupling shaft to which a movable insulator for each phase is coupied and which shaft may be operated to simultaneously move the insulators, an electrical current-carrying cartridge between the fixed and movable insulators for each phase, means in the cartridge to break the current between the insulators when the shaft is operated, an operating arm coupled to the transverse phase-coupling shaft, a trigger to support the operating arm, a trigger release, and an electrically operated solenoid to operate the trigger release.

4. An improved electrical interrupter for a inulti-phase system according to claim 3 in which said operating arm is restrained by a reset arm coupled to a lever arm and reset rod, and the reset arm is held by said trigger.

5. An improved electrical interrupter for a multi-phase system characterised by a fixed and a movable insulator for each phase which serve as terminals for current-carrying lines, a support upon which the fixed insulator for each phase is carried, a transverse phase-coupling shaft to which a movable insulator for each phase is coupled and which shaft may be operated to simultaneously move the insulators, an electrical currcnt-carrying cartridge between the fixed and movable insulators for each phase secured to one insulator and guided by the other, an operating arm secured. to the transverse phase-coupling shaft, a trigger to support the operating arm, a catch for the operating arm releasable by the trigger, an electrically operated trip coil to operate the trigger, an actuating pin on the movable insulator for each phase, and said cartridge for each phase comprising a fixed contact and a withdrawable spring loaded contact and a lockpin to normally hold the contacts together, said locking pin being in the path of the said actuating pin to move the locking pin to allow the contacts to disengage under spring action when the movable insulator shaft is rocked.

6. An improved electrical interrupter according to claim 5 in which the withdrawable contact is held in engagement with an annular surface on the fixed contact by the said holding pin which has its one end held in. a split portion of the withdrawable contact and its other end in line with the line of movement of the said actuating pin.

'1. An improved electrical interrupter for a multiphase system characterised by a fixed and a movable insulator for each phase which serve as terminals for current-carrying lines, a support upon which the fixed insulator for each phase is carried, a transverse phase-coupling shaft to which a movable insulator for each phase is connected and which shaft may operate to simultaneously move the insulators, an electrical curren carrying cartridge between the fixed and ovable insulators for each phase secured to one ulator and guided by the other, an operating coupled with the transverse phase-coupling a trigger, a catch for the operating arm releasable by the trigger, an electrically operated trip coil to operate the trigger, an operating pin on the movable insulator for each phase, said cartridge for each phase comprising a fixed annular contact, a withdrawable contact to fit therein, a holding pin to lock the contacts together, and a spring to urge the contacts apart, said cartridge being in the form of a cylinder having a frangible disc at one end and having the holding pin held in a split portion of the withdrawable contact, the cylinder containing an arcextinguishing liquid.

8. An improved electrical interrupter for a inulti-phase system characterised by a fixed and a movable insulator for each phase, a support upon which the fixed insulator for each phase is carried, a transverse phase-coupling shaft to which a movable insulator for each phase is secured, which shaft may rock in bearings on the support, an electrical current-carrying cartridge between the fixed and movable insulators for each phase secured to one insulator and guided by the other, an operating arm coupled to the transverse phase-coupling shaft, a trigger to support the operating arm, a catch for the operating arm releasable by the trigger, an electrically operating solenoid to operate the trigger, said cartridge for each phase comprising a fixed contact, a withdrawable contact to interrupt the flow of current, a holding pin held in a split por-- tion of the withdrawable contact and actuated by displacement of the movable insulator, and the 9 cartridge containing a solid arc-extinguishing material.

9. An improved electrical interrupter for a multi-phase system characterised by a fixed insulator for each phase, a transverse phase-coupling shaft carried in hearings on a support, a movable insulator secured to the shaft and extending outwardly for each phase to serve as a terminal for a current-carrying line, a current carrying cartridge between the fixed and movable insulators for each phase secured to the said fixed insulator and guided by the said movable insulator, releasable contacts in the said cartridge, spring means to urge the said contacts apart, a locking pin to normally hold the said contacts together, an operating connection between the said movable insulator and the said pin, a mechanism box carried by a support for one phase,

an operating arm coupled to the shaft and carried in the mechanism box, an electrically operated trip coil carried by the mechanism box, a plunger actuated by the trip coil, a reset arm restraining the operating arm, a catch restraining the reset arm and actuated by the plunger to release the weight of the movable insulator, and spring loading to control the striking force of the movable insulator for each phase.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,522,498 Conrad Jan. 13, 1925 1,937,409 Lemmon et al Nov. 28, 1933 2,098,692 Pittman et al Nov. 9, 1937 2,331,221 Ortensi Oct. 5, 1943

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