DD233253A1 - CURRENT LIMITING AND SHORT CLOSURE DEVICES - Google Patents

Abstract

The invention relates to an electrodynamic drive to automatically limit a fault current in electrical energy feeds by means of commutation and / or short-circuit contacts and / or to suppress a fault arc. The aim and task is to build a short circuit current limit with an electrodynamic drive, which is fed from the fault current itself, the elements Auslösent the Schalterbetaetigung are subjected to a strong acceleration. This is achieved in that a primary winding is arranged in the core window of a magnetic core, which lies opposite a winding through which short-circuit current flows, which winding is divided into two parts, a short-circuit winding and a short-circuiting cylinder. The short-circuit winding and the short-circuiting cylinder are connected to switching elements which interrupt the current path and cause a higher current to flow in the short-circuiting cylinder and at the same time cause a strong acceleration of the same by an induction increase at the short-circuiting cylinder. By means of turn-off thyristors, the short circuit in the short-circuit winding can be canceled or produced, depending on whether the short-circuit cylinder is to be accelerated sharply or left without movement. Fig. 1

Description

Field of application of the invention

The invention relates to an electrodynamic drive in order to automatically limit a fault current in electrical energy feeds by means of commutation and / or short-circuiting contacts and / or to suppress an arc fault.

Characteristic of the known technical solutions

Short-circuit current limiting means and the short-circuit current limiting reactor and the transformer adapted in the short circuit voltage have the disadvantage of high voltage drop even in rated operation and the voltage fluctuations with changing load.

There are also chokes and transformers have been proposed in which only a reactance increase in the event of a fault occurs more or less quickly. Patents to be considered are:

DO-PS 204568, H 01 F, 31/06

DD-PS 97771, H 01 F, 27/36

DD-PS 116106, H 02 H, 9/02

DD-PS 130084, H02H, 7/22

DD-PS 136205, H02H, 9/02

DD-PS 136206, H02H, 9/02

In the above cases, usually additional winding parts and switches are necessary or to accelerate masses, which still requires considerable effort even in the functional integration transformer or reactor with short-circuit current limit.

It is also known to limit the short-circuit current level before switching the circuit breaker by means of a limiter, but this requires rapid activation of the explosive charge and, in the event of misfiring, the desired effect does not occur.

For LV systems permanent fuses have been tested, but they do not yet show the necessary creep behavior, ie. H. sometimes they have to be overtaken after a few limit circuits.

In the patent DE-OS 2530717 a commutation circuit with a switching device with energy storage and a switching tube, the controllable windings is required, described, which is a total of consuming in the control part and also in the primary circuit requires significant expenses.

As far as the short-circuiting solutions are concerned, after a fast arc detection by means of arc monitors, ie optical sensors and also other criteria (current and voltage curve), it is very easy to bring about a short circuit to earth. The mechanical short-circuiters require considerable expenditure in the drive in order to achieve short switching times, or they are too slow or they require maintenance or standby production after each shift.

Other short-circuiters such as high-current thyristors (DE 2947700 A1) or plasma short-circuiters often do not have the necessary current carrying capacity of 50 ... 100 ms and then require an additional mechanical short-circuiter (metallic current path in shunt).

There are known for fast switches and short circuit electrodynamic drives, but all require an energy storage source in the form of a capacitor and to a circuit breaker to achieve appropriate times.

Object of the invention

The aim of the invention is to build a short-circuit current limiter with metallic short-circuiter or a Kurzschlußstrombegrenzer with an electro-dynamic drive, which is fed from the fault current itself.

-2- 71881

Explanation of the essence of the invention

The invention has for its object to release by means of winding arrangements on a winding such force effect that it executes in the desired manner very quickly movement for the purpose of a switch operation and subsequently inserts a short-circuiter, wherein the short-circuit current is also limited that is achieved according to the invention in that a primary winding is arranged in the core window, which is opposite a winding which flows through the short-circuit current and which consists of short-circuit winding and short-circuiting cylinder, wherein the short-circuit current carrying winding parts are guided in a well-movable manner on the magnetic core. In place of the primary winding, a primary conductor designated as Hmleiter can be arranged in the core window, flanked by two movable jerk conductors, which drive the short-circuit current. Both the short-circuit winding and the short-circuiting cylinder are connected to switching elements which interrupt the current path and in the short circuit The current path can be interrupted by a contact tongue even with a pure primary conductor arrangement, so that in the low-mass jolt conductor the entire short-circuit current flows and thus a large acceleration is granted in an extended Embodiment are provided by a fault current detection device controlled switching elements z. B can be made of turn-off thyristors or transistors and with which either the short circuit in the short circuit winding canceled and thus the Kurzschlusszylmder a strong acceleration can be issued or made at start-up or inrush a short circuit and thus unwanted movement of the short-circuit cylinder can be prevented The contacts of the switching elements or the contact tongue for the interruption of the current path are arranged in the core window to drive the switching arc in a Kuhlkamin The ratio of the masses of short-circuit winding to Kurzschlusszylmder or larger return conductor to smaller return conductor is designed by appropriate winding or Leiteraufteiiung that it is less than 1 is

exemplary

In the drawing, the invention will be explained in more detail in the drawing, Fig. 1 shows an arrangement of the short-circuited winding parts with the self-acting Offnerkontakten and the controllable Offner- and closing gates in the core window 2 of the magnetic core 1 are the primary winding 3, the turn-off short-circuit winding 4 and In the normal operating state, the primary flux of the primary winding 3, which generally consists of one winding, is compensated by the short-circuited short-circuit winding 4 and the short-circuiting capacitor 5. The short-circuiting winding 4 which can be switched off is for the purpose of adaptation to the switching elements 6, 7, 8, 9 from several turns. In the event of a fault, from a current strength ι> ρ I _n , where ί _{η is} the value of the rated peak current and the ratio ρ instantaneous residual current to rated current is two, the short-circuited short-circuit winding 4 is moved away from the primary winding 3 against the spring force of the spring 10 and the switching element 6, which may be located in the magnetic field in the core window 2, lifts the short circuit for the short-circuit winding 4, so that the Kurzschlußzylmder 5 against the spring force of the spring 11 moves away from the primary winding greatly accelerated and thereby opens the contacts of the switching element 7, then opens the commutation 12 and upon reaching the Nennschaltweges a short-circuiting contact 13 closes and a switching device 14, the busbar to ground sets. The high dynamics of the movement of the short-circuiting cylinder 5 is achieved in that in case of failure, the entire primary current passes to the Kurzschlusszylmder 5 when the switching elements 6 and / or 7 and / or 8 cancel the short circuit of the short-circuit winding 4 and thus the differential equation for the movement in in this case

m ₅ x + ex = F, (t)

is shown, while in the case of non-subdivision of the short-circuit winding the differential equation for the movement through

(m ₄ + ITi ₅ ) χ + ex = F, (t).

In this case, the short-circuit winding 4 would be connected to the short-circuiting cylinder 5 to a whole, which has the total mass m ₄ + m ₅ Here, m _{4 is} the mass of the winding 4 and m _5, the mass of the short-circuiting cylinder 5 plus all those parts at the Kurzschlusszylmder are attached and moved in the formulas mean further χ way, χ acceleration, с spring constant and F, current force. The fault in the short-circuit cylinder 5 existing very high current density is irrelevant to the function of the electrodynamic drive The opening of the short circuit of the short-circuit winding 4 can also be done from a rapid fault current detection by driving the switching element 8, so that before opening the contacts of the switching elements 6, 7 the greatly accelerated movement of the short-circuiting cylinder 5 begins The switching element 9 is constantly open and serves to make the electrodynamic drive insensitive, z. B. when start-up or inrush currents should not be limited by the short-circuit winding 4 is short-circuited by the switching element, that is, even in the case that the switching elements 6 and / or 7 cause a cancellation of the short circuit of the short-circuit winding 4 By the resistor 16 is indicated be that by actuation of the switching elements 6, 7, 8, 9 and the Kurzschlu.o vickl'jng a reduction of the switching voltages is reached At the end of Nennschaltweges the movement is braked by means of a shock absorber 17

-z- 718

In Fig. 2, the basic arrangement of a pure primary conductor arrangement is shown as an electrodynamic drive with the Kommutierungskontakt within the magnetic field. Here, the magnetic core 21 and the core window 22 is only indicated. In the core window 22 are the forward conductor 23 and the two return conductors 24; 25, wherein the return conductor 25 is designed with the smaller cross-section. With a fault current i> ρ · I _n , the return conductor 24 moves away from the forward conductor 23 up to the point at which the contact tongue 26 makes no contact with the return conductor 24, so that then the entire current is taken over by the return conductor 25. From this point, the return conductor 25 moves very rapidly due to the increased current force and the small conductor ground away from the forward conductor 23, so that when a Kommutierungskontaktes for a limiting impedance, a current limit can be made or quite generally a switching device is actuated. The current bands 27; 28 outside the core window 22 allow a free movement of the return conductor 25 to a distance corresponding to the Nennschaltweg. Instead of the current bands 27; 28 also cone rollers or other constructive solutions can be selected. Instead of the parallel guidance of the return conductor 24; 25 to Hinleiter 23, the attachment of the return conductor 24; 25 also occur at a point on the power supply side on the side of the current band 28, so that the return conductors 24; 25 from each other in a scissor-like manner. In both variants of the embodiment shown in Fig. 2, the contact point of the return conductor 24 is placed with the contact tongue 26 within the core window 22, so that the switching arc by the force

S ₁ i (s 2 3)

extended quickly and led to the outside and where appropriate cooled on fins. In the formula, F _{Li is} force on the arc, Z _{1 is} aspect ratio, i is the instantaneous total short-circuit current, s is the arc length, and B is induction in the core window. For Zi, a value of 0.75 is recommended so that m is ₅ / m ₄ = Ѵ z.

Claims (7)

-1- 71881 Invention claim: 1. current limiting and short-circuiting device in electric power plants with magnetic circuit, which is designed as a shell or pot core and carries at least one winding, characterized in that a primary winding (3) and a forward conductor (23) is arranged in the core window, that the primary winding a is opposed by the short-circuit current through which winding is divided into two parts, the short-circuit winding (4) and the return conductor (24) and the short-circuiting cylinder (5) or the return conductor (25), both short-circuit current carrying winding parts are guided well movable on the magnetic core in that the short-circuit winding (4) and the short-circuiting cylinder (5) are connected to switching elements (6, 7); and that a switching arm with contact rod is attached to the shorting cylinder (5), shorting a short-circuiting contact (13) via the switching device (14). 2. Current limiting and short-circuiting device according to item 1, characterized in that a switching element (8), e.g. a turn-off thyristor is provided which cancels the short circuit of the short-circuit winding (4). 3. Current limiting and short-circuiting device according to item 1 and 2, characterized in that a switching element (9) as normally open, z. B. a transistor or a turn-off thyristor is provided which establishes the short circuit of the short-circuit winding (4) at start-up and shutdown. 4. current limiting and short-circuiting device according to item 1, characterized in that the contacts of the switching elements (6; 7) are arranged in the core window. 5. Current limiting and short-circuiting device according to item 1, characterized in that a contact tongue (26) is arranged in the core window. 6. Current limiting and short-circuiting device according to item 1 to 5, characterized in that the ratio of the masses of short-circuit winding (4) and short-circuiting cylinder (5) is less than 1 (гт ^ гтц <1). 7. Current limiting and short-circuiting device according to item 1 to 5, characterized in that the ratio of the masses of return conductor (24) and return conductor (25) is less than 1 (m ₂ 5: m ₂ 4 <1). For this 2 pages drawings