DE1169014B - Current-limiting low-voltage circuit breaker - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: H 02 d

German class: 21c -68/01

Number: 1169 014

File number: L 40831 VIIIb / 21c

Filing date: December 21, 1961

Opening day: April 30, 1964

For current-limiting disconnections of high-current Circuit breakers have become known to short-circuits in three-phase networks of low-voltage systems. the contact pieces with the help of a conductor loop located in each of the three poles Open electrodynamically against an existing spring force. The opening is mostly during the first Half-wave (surge short-circuit current) of a short-circuit current aimed at the accumulation of the full To prevent surge short currents.

Circuit breakers whose contact pieces in each pole track, for example with the help of anti-parallel conductors in Open depending on the short-circuit current, can only work to limit the current if their contacts disconnected in less than 5 ms. Depending on the type of short-circuit current occurring - full symmetrical or fully asymmetrical - a more or less strong current limitation is achieved here.

Current-limiting low-voltage circuit breakers that operate according to the principle described work, their contacts open after about 3 ms; the total switch-off time is 8 to 10 ms.

For very powerful systems, in which the effective value of the short-circuit current can be up to 100 kA, current limitation in the first half-wave can only be achieved with difficulty with known current-limiting circuit breakers. If one takes into account that with a fully asymmetrical short circuit for a power factor cos Φ = 0.3 the peak value of the surge short circuit current is already 200 kA and the current edge of the first half-wave has a current rate of increase of more than 35 kA / ms, it becomes clear that after one Contact opening time of 3 ms the current has already accumulated to more than 100 kA. If, on the basis of empirical values, a further 50% is added up to the final limit for the forward current in the arc, then the forward current is finally 15OkA. If one assumes Ό = 500 V, then there is one phase during the switch-off

Current-limiting low-voltage circuit breaker

Applicant:

Licentia Patent-Verwaltungs-G. m. b. H.,

Frankfurt / M., Theodor-Stern-Kai 1

Named as inventor:

Heinz Fehling, Einfeld,

Dipl.-Ing. Ortwin Küster, Kelkheim (Taunus)

Uph

500

= 290 V,

that is about 43.5 MVA at the moment of switching.

This high power would have to be implemented in at least one pole path in the arc extinguishing chamber will. The effort for such an arc extinguishing chamber would be too great and uneconomical Dimensioning for a low-voltage circuit breaker is probably unacceptable. Also would be at a forward current of more than 100 kA, which is expected from a current-limiting circuit breaker Protection of the disturbed system parts against the effects of electrodynamic forces is no longer given.

In addition to the specified disadvantages, the conventional circuit breaker is used for current-limiting circuit breakers Design from a short-circuit current level usually already at 7 to 10 · / "from the dynamic one Strength of the contact system exceeded. Either the trip is already in this area of the switch by means of one that acts on all three pole tracks and is built into each individual pole track magnetic trigger initiated or with the help of the current loop by releasing a mechanical Locking causes.

Below this and essentially from the components (contact force spring, current loop, Contact pieces and the like) of the switch-dependent area is to be expected in a critical area which the contact pieces open neither electrodynamically nor magnetically, but already their electrodynamic one Lose strength due to partial removal of the contact force (loop effect). This critical area can, for example, give rise to welding of the contact pieces.

For many protective tasks in low-voltage systems, it is essential to have circuit breakers in to selectively stagger the feeders behind the feeding transformer. A gradability only with Achieving current-limiting circuit breakers of the conventional design is technically hardly conceivable, because there is a sufficient tripping time difference between two limiters in a cable run does not exist. It has heretofore been necessary, for example, the transformer switch as a staggered circuit breaker partially with

409 587/439

to provide additional delay elements. About the economic disadvantage of two switch series To avoid power circuit breakers have been proposed that use interchangeable (mechanical) coupling links or with the help of exchangeable conductor pieces in the pole tracks can be used for current-limiting as well as for staggered tasks. In both cases the interference within the pole tracks is not

current release initiated lock release can the switch receives a delay time of several 100 ms suitable for staggered tasks.

The electrodynamic strength of the contact system is in the embodiment by the as Ensures a narrow current loop formed lamellar contact arrangement, which has proven itself in practice Has. The one in the lower part of the current path

with the moving contact lever firmly connected driver pin the contact system in closed Position.

The 5 tripping unit located in the lower part of the current path consists on the one hand of the known, for overcurrent and short-circuit switching required magnetic quick release, the is mostly designed as a complete module according to the state of the art and both mechanically

admittedly, if one or the other type of switch io cally acting elements for short-term delays function is desired. as well as thermally acting links (bimetal

Through the invention, the use of the solver) for long-term delays can be included, known current-limiting circuit breaker limiting disadvantages eliminated, and also overcurrent) the unlocking of the switch lock 17 such a device can be effected without 15 according to the invention. When switching on delay elements Conversions for both current limiting and for or only indirect, for example via work staggered Tasks are used.

This is achieved according to the invention in that
the moving part of a contact 20 that is influenced by the trip units and the switch mechanism
systems of high dynamic strength, whose im
fixed contact part housed contact force springs
are supported by the dynamic effect of the current, is locked in such a way that in the state
the latching the current forces a contact force 25 additionally arranged and main current flow reinforcement, but after the release a contact electrodynamic quick release consists of the

Coil 7 and the short-circuit ring 7 '. The short-circuit ring is with the help of an eye bolt 18 to the The pivot lever 19 is coupled, which in turn is mounted in the pivot point 20.

A locking pawl 21 can be used to block or release the pivot lever 19, depending on whether the position II or I of the locking pawl is selected.
35 The function of the self-switch described above is as follows in the event of a short circuit:

J. Position I of the locking pawl 21

The short-circuit current flowing through the pole track

via further existing triggers and the switching 40 causes a close magnetic coupling between

lock mechanism takes place. the main current coil 7 and the short-circuit ring T.

Is z. B. the electrodynamic trigger mecha- The force components of both magnetic fields

nisch locked (locked), the inventions repel each other and give the short-circuit ring

proper circuit breakers without current limits - high acceleration. Speed and in a customizable version. One and the same 45 impulse of force that is imparted to the ring

The device is therefore able to operate without having to be replaced, depending on the steepness of the current edge in the

Irish or mechanical parts optionally current- first half-wave, the short-circuit current level and the

Limiting or selective grading tasks to the number of turns of the main current coil. Is located

take over. the swivel arm in the unlocked state, like this

In Fig. 1 is an exemplary embodiment of the invention. The short-circuit ring snaps in the direction of the arrow up to

object shown. Limitation 22. In this way have already been

When the switch is closed, the operating arm flows via the swivel arm 19, which acts as a lever bar current via the fixed connector 1 to the pawl 13 in with the aid of the coupling member 11 and 12 Loop shape arranged and resiliently lifted and the movable contact lever freige-lamellar contacts 2 and 3, will give from the mobile 55. At the same time, the release lever 11 hits the Contact lever 4 taken over with tear-off piece 5 and striking piece 23, which means an accelerated opening over a current bolt 9 to the trigger unit is achieved with movement of the movable lever, the main current coils 6 and 7 and the lower one. The combination »unlocking and impact pulse fixed connector 8 out. The movable one directly on the contact «is for the momentary shift lever 4 is pivotable on the power bolt 9 60 speed of the contact opening is particularly important. In the stored, which is also on its two, with the specified combination achieved resistance to distortion Bearing journals fitted with bushings the times are already at a current value of 20 kA Switching arms 10 and 10 'carries. less than 3 ms with fully asymmetrical short-circuit

The release barrel is also around the pivot point 9. With a fully symmetrical short circuit lever 11 mounted, which with the pull rod 12 and a 65 can because of the steep current edge at the short circuit the switching arm 10, 10 'pivotably arranged begins the contact opening time in the described Pawl 13 is coupled. The pawl 13 holds the assembly down for a further millisecond pawl point 14 can be set by just overlapping one. In this version, a current-

cause opening and that the latching is done by a series connected to each individual pole, very fast working, preferably electrodynamic trigger is canceled.

So it is the electrodynamic effect of the current both to increase the contact force and also used to open the contact, but the contact can only be opened when the electrodynamic trigger that allows.

Furthermore, by blocking the electrodynamic release, for example by an actuator, caused that this trigger is not effective and that the contact opening only then

limiting switch-off secured in the event of high short-circuits.

In order to avoid bouncing back of the movable switching arm 4, which opens with high acceleration, the limiting plate 24 'of the holding rod 24 meets a preferably non-elastic material existing limiting ring 25. The movable switching arm is thus held in its open position at the same time, so that when the lock falls a re-activation of all three pole tracks is κ> is guaranteed.

2. Position II of the locking pawl 21

If the possibility of movement of the pivot arm 19 is canceled by the pawl 21, it does not take place the opening of the latching point 14 until it is triggered via the lock lock with the aid of the magnetic trigger 16.

In this position, the circuit breaker can be used again for selective grading tasks. especially since the short-circuit-proof contact system is able to accept surge short-circuit currents without any consequences allowed.

In Fig. 2 is the mode of operation of the circuit breaker specified according to the invention for low-voltage systems shown on the short-circuit current curve in one phase. Current-limiting tripping I when the swivel arm is not locked and normal release for staggered tasks II when the swivel arm is locked Swivel arm.

Claims (8)

Patent claims: 1. Current-limiting low-voltage circuit breaker in which the contact system seeks to open up under the dynamic action of the current flowing over it, thereby characterized that the influenced by the trip units and the switch mechanism, moving part of a contact system of high dynamic strength, its in the fixed contact part accommodated contact force springs supported by the dynamic effect of the current are locked in such a way that, in the locked state, the current forces increase the contact force, after the release but cause a contact opening and that the latching by a very fast working, preferably one, connected in series with each individual pole electrodynamic trigger is canceled. 2. Current-limiting circuit breaker according to claim 1, characterized in that the very Fast-acting releases except for releasing the latching of a pole of the contact system also serves to open the contact system. 3. Current-limiting circuit breaker according to claim 1 and 2, characterized in that in addition to the electrodynamic trigger, other such. B. electromagnetic, bimetallic Triggers are provided which cause the contact to open via a switch lock. 4. Current-limiting circuit breaker according to claim 3, characterized in that a the electrodynamic trigger optionally ineffective or effective making actuator provided is so that without remodeling or replacement of electrically or mechanically active Divide the device can be used for current-limiting switching or selective grading. 5. Current-limiting circuit breaker according to claim 3 and 4, characterized in that a the electrodynamic release optionally locking or releasing actuator is provided is. 6. Current-limiting circuit breaker according to claim 1 to 5, characterized in that each contact system consists of a combination of two antiparallel conductors, which when released work through the trigger in the sense of an electrodynamic contact opening. 7. Current-limiting circuit breaker according to claim 1 to 6, characterized in that the Electrodynamically operating triggers in a known manner from one or more main current flows Windings and one of these separate short-circuit ring. 8. Current-limiting circuit breaker according to claim 1 to 7, characterized in that for Damping and opening restriction of the movable switching arm after unlatching directly connected to this, guided through the fixed pole carrier, preferably made of insulating material Existing shift rod is used, which with its limiting plate on a counter bearing bumps, which can consist of non-elastic metal or plastic. Considered publications: German Auslegeschrift No. 1 082 971,
073 600; German patent application E 283 VIIIb / 21c (announced on August 30, 1951); Swiss Patent No. 294 486; French Patent No. 1187 184; Revue generate de l'Electricite, May 1958, pp. 259 to 276; Bull, de la Societe Francaise d'Electricien, 1958, Pp. 447 to 458. 1 sheet of drawings 409 587/439 4.64 © Bundesdruckerei Berlin