US1787931A - Quick-break circuit-breaker system for large currents - Google Patents

Description

' Jan. 6, 1931.

H. BESOLD 1,787,931

QUICK BREAK CIRCUIT BREAKER SYSTEM FOR LARGE CURRENTS Filed 001;. 23, 1928 Patented Jan. 6, 1931 UNITED STATES PATENT, OFFICE HANS BESOLI), OF BEBLIN-SIEMENSS'IADT, Gm, ABSIGNOB 1'0 SIEMENS-863116!- EBTWEBKEAKTIENGESELLSCHAFT, OI BEBLIN-BIEMENSSTADT, GERMANY, A 003- rom'rron orcnnmm I QUICK-BREAK CIRCUIT-BREAKER SYSTEM FOR LABGE CUBBENTS Application filed October 28, 1928, Serial No. 814,341, and in Germany Octolier 28, 1987..

-M invention relates to quick-break circuitbrea ers for large currents, especially for large direct currents. I

Ordinary overload circuit-breakers for I, high current ratings are obtained in a simple manner by making the contacts for closing the circuit correspondingly large and by takin care that by connecting in parallel a plura ity of units, such as laminated brushes, the

temperature rise at the contacts remains with in ermissible limits.

n desi ning quick-break or high speed circuit brea ers for heavy currents difiiculties arise, because the increase of the massof the 15 contacts in quick-break circuit breakers leads to such large acceleration forces, that uneconomical constructions result.

The connection in parallel of a plurality of quick-break circuit breakers does not solve the 20 problem in a satisfactory manner, because the distribution of current over the individual breakers in the event of sudden current rushes is by no means uniform, so that it is impossible to obtain a simultaneous opening of all u the breakers.

In quick-break circuit breakers carrying a series winding on the holding magnet 1t has already been suggested to connect the series coils of the individual parallel circuit breakers in series, to bring about the simultaneous tripping of the breakers connected in parallel.

My invention relates to a quick-break circuit breaker or automatic switch, which consists of a combination of a plurality of individual breakers, the contacts of which are connected in parallel to the main line to be interrupted, and to means for obtaining an accurately simultaneous tripping of all the individual circuit breakers.

One objectof my invention is to provide a of which are connected in parallel with the hue or circuit to be interrupted, the individual breakers being controlled by magnets with windings and all of them being opened absolutely slmultaneously, by inducing a current rush or impulse in the windings of all ma nets by the aid of a transformer common to a 1 individual breakers, when a sudden change of the current occurs in the main line.

A further object of my invention isto employ quick-break circuit breakers with holdmg magnets having windings, which hold the breaker closed as long as the magnet winding istrayersed by a definite holding current, the windings being connected to a source of direct current of constant voltage and the holding current being extinguished instantaneously by inducing a volta e in the circuit of the holding windin WhlCh destroys the volta e of the source 0 direct current and also the self-induction voltages developed in the wind- 1n when the current changes.

he details of my invention'will be more fully described with reference to'the drawing aflixed hereto and forming part of my specification and in which embodiments of my invention are illustrated by way of example.

In the drawings Fig. 1, illustrates a diagram of connections of a quick-break circuit breaker according to my invention, and

Fig. 2, a dia ram of connections of a modified constructlon of, my improved circuit breaker.

Referring to Fi 1, the quick-break circuit breaker illustrate may consist for instance of two individual breakers. 30 is the main direct current line to be interrupted. It branches at the point 31 and forms the two parallel-branch lines 32 and 33, which unite again at the point 34 to form the common line 30 again. In the branchline 32 is connected the pair of contacts 16 and in the branch line 33 the pair of contacts 17. These pairs of contacts are designed as arrester horns, the horns 161, 171 being stationary and the horns 162, 172 movable, for which purpose they are mounted respectively on one-armed contact levers 112, 122 pivoted on the stationary pins 113, 123. Onthese contact levers tracted state.

are mounted the armatures 111, 121 of the holding magnets 11, 12. The separating springs 114, 124 are at one end attached to the armatures 111, 1 21 and are stretched when the armatures have been attracted by their magnets. They thus have the tendency to pull the armatures off the magnets. The limbs of the holding magnets 11, 12 carry the coils 13, 14 connected in series to the coil 18 and across the source of direct current 15. The coil 18 is as secondary winding located on the core 19 of the transformer carrying the primary winding 20. This winding 20 is connected in the circuit 30 to be interru ted.

he mode of operation of the system is as follows: In normal operation only the con stant Voltage of the source of current 15 is operative in the circuit of the coils or windings 18, 13, 14, under the action of which the coils or windings 13, 14 of the holding magnets 11, 12 are traversed by a constant holding current. This holding current generates a holding flux traversing the magnet body and the armatures 111, 121 of the holding magnets, which maintains the armatures in the at- The movable contact horns 162, 172 at the free ends of the contact levers 112, 122 are thus in contact with the stationary contact horns 161, 162, so that the contacts 16, 17 are closed and the current trav erses both parallel branches of the line 32, 33. The separating springs 114, 124 are then in the stretched state.

If sudden fluctuations of the current develop in the line 30 to be interrupted, a volta e is induced in the secondary winding 18 0% the transformer 19. This winding 18 is so connected, that in the event of a corresponding speed and value of the primary current change, this voltage destroys or compensates the constant voltage of the source of direct current 15 and all the voltages of the self-induction developed during the cur rent fluctuation in the windings 13, 14 and 18, so that the holding current disappears almost instantaneously. No attracting force is now exerted upon the armatures 111, 121 by the magnets 11, 12 and the contact levers 112, 122, following the force of the stretched separating springs 11.4, 124, pass into the opening position. The contacts 16, 17 are thus broken and the line 30 is interrupted. Since the induced voltage in the windings 13, 14 is generated by the winding 18 of the transformer, the armatures are released absolute- 1y simultaneously, provided the dimensions of the holding magnets 11, 12 and their windin s 13, 14 are equal.

eferring to Fig. 2 of the drawing, it will be seen,.that the main line 30 to be interrupted branches in the points 35 and 36 into three parallel branch lines 37, 38 and 39. They unite again in the points 40 and 41 and continue as common line 30.

In the branch line 37 is connected the pair of contacts 16, in the branch line 38 the pair of contacts 17 and in the branch line 39 the pair of contacts 25. Each of these pairs of contacts consists of a stationary contact horn 161, 171, 251 and a movable contact horn 162, 172, 252. The movable contact horns are mounted at the free ends of the contact arms 112, 122, 232, which rock upon the stationary pivots 113, 123 and 233. They are connected with magnet armatures 111, 121. 231 controlled by separating springs 114, 124, 234, which are stretched when the armature contacts with the magnet. The magnets 11, 12, 23 carry on one limb the windings 13, 14 and 24 respectively. On the other limb are located the series windings 21. 22, 26, which are connected in the branch lines 37. 38, 39, which the respective breaker should interrupt. 19 is the core of a transformer, the primary winding 20 of which is connected in the line 30 to be interrupted. The transformer carries three secondary windings 181. 182. 183. The winding 181 is connected to the winding 24 of the holding magnet 23 across the source of direct current 15. The two other secondary windings 182 and 183 of the transformer are respectively connected with the windings 14, 13 likewise across the source of direct current 15.

The system functions in the following manner: During normal operation the windings 13, 14, 24 of the holding magnets are traversed by a constant holding current generated by the source of current 15. The series windings 21. 22, 26 of these magnets are simultaneously traversed by the branch current, which flows in the lines 37, 38, 39. The series windings are so connected. that their ampere turns are opposed to the ampere turns of the holding winding 13, 14. 24. The series windings are so dimensioned, that by their action at a properly rated operating current the holding flux originating from the holding coils 13, 14, 24 is weakened so far only, that the resulting magnetic holding flux just holds the armatures of the magnets in the attracted position. The contacts 16, 17 and 25 of the breakers are then closed. Currents thus How in the three branch lines 37, 38 and 39 and the separating springs 114, 124 and 234 are stretched.

If in consequence of a fault in the external circuit the current rises in the line 30 beyond a certain value, for which the holding magnets have been adjusted. the ampere turns originating from the series coils 21, 22, 26 and weakening the holding flux increase to such an extent. that the resulting holding flux no longer sufiices to maintain the armatures in the attracted position. The contact levers 112, 122, 132 are then under the action of the stretched separating springs 114, 124, 234 moved into the opening posig opened by sufiicient rate and .by

m this case voltages of correspon ing magnitude are induced in the secondary windings 181, 182, 183 of the transformer 19. The windings 181, 182, 183 are so connected and dimensioned, that the sudden chan e of the 15 current at which the break should ta e place,

produces a voltage, which destroys or counteracts the voltage of. the source of direct current 15 and also the voltages of the selfinduction developed in the coils 13, 14, 24,

go 181, 182, 183 by the sudden current fluctuation. The holding current thus disappears almost instantaneously and the armatures 111, 121, 131 of the holding magnets are released. The contacts 16, 17, 25 are then the contracting separating springs. i

The just described system may also be changed by omitting the series coils 21, 22, 26 and providing the holding magnets with so the holding coils 13. 1.4, 24 only. In tl'llSCflSB the circuit is not interrupted in the event that the overload has attained a definite absolute value and the contacts are opened only, when the current in the mains 30 rises at a a correspondingly great amount. On the other hand the individual switches are: greatly simplified in their construction by dispensing with the series coils. 1

The system described has the further advantage, that the holding winding of each holding magnet may be accurately adjusted with the corresponding secondary of the transformer. It is in this way possible by a judicious choice of the number of turns of the holding winding of the magnet or by means of series resistances inserted into the connecting leads to adjust the holding power so accurately, that all switches open at the same moment as soon .as an overload, a change of the current or a short circuit develops on the line.

Various modifications and changes may be made without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a quick-break circuit-breaker system for large direct currents, in combination, a plurality of individual circuit-breakers having their contacts connected in parallel with the line to be interrupted, magnets with wind. ings adapted to control said contacts, a transformer having the primary portion of its winding connected to the line to be inter- 66 rupted, and the secondary portion connected to the windings upon the magnets of said individual circuit-breakers. Y e

2. In a nick-break circuit-breaker system for large irect currents, in combination, a lurality of individual circuit-breakers havmg their contacts connected in parallel with the line to be interrupted, holding magnets with windings for each of said circuit-breakers, and adapted to hold said breakers closed as long as the windings arc traversed by a holding current of definite value, a transformer having a primary and a secondary winding portion, said primary winding portion belng connected to the line to be interrupted and said secondary winding portion being connected to the windings of said hold ing magnets, and a source of direct current connected in the leads between said second ary winding portion and said windings of the holding magnets.

3. In a quick-break circuit-breaker system for large direct currents, in combination, a lurality of individual circuit-breakers havmg their contacts connected in parallel with the line to be interrupted, holding magnets with windings for each of said circuit-breakers and adapted to hold said breakers closed as long as the windings are traversed by a holding current of definite value, a transformer having a primary winding and a plurality of secondary windings, said primary winding being connected to the line to be interrupted, each of said secondary windings of said transformer being connected with one winding each of a holding magnet, and a source of direct current connected in the leads between said secondary windings and said windings of the holding magnets.

4. In a quick-break circuit-breaker system for large direct currents, in combination, a plurality of individual circuitbreakers havmg their contacts connected in parallel with the line to be interrupted, holding magnets with windings for each of said circuit-breakers, each holding magnet being provided with a constantly excited holding winding and a series current Winding in series with the corresponding circuit-breaker, both of said windings adapted to hold said circuit-breaker closed as long as a resulting magnetic holding flux of definite value. exists, a transformer havin aprimary winding and a pluralit of secon ary windings, said primary winding being connected in the line to be interrupted, each of said secondary windings of said transformer being connected with a winding each of a holding magnet, and a source of direct current connected in the lead between said secondary windings and said constantly excited holding windings on the holding magnets.

In testimony whereof I aflix my signature.

HANS BESOLD.

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