SU913516A1 - Current limiting device - Google Patents

Description

The invention relates to electrical engineering and energy and can be used in low-voltage networks to protect against short-circuit currents of transformers operating in the unit with generators, as well as to limit short-circuit currents in low-voltage power lines.

Known construction the current-limiting reactor containing magnetically connected in parallel and operating winding ¹⁰ nye spatially separated on different magnytoprovoda rods, creating · Suitable counter magnetomotive force and a magnetic shunt in the circuit breaking area disposed thereon with the control winding. With the help of a shunt and a control winding, which, depending on the load, switches ¹⁵ (short-circuited or disconnected), the operation of the reactor is controlled [11.

The disadvantages of this design are

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large voltage drop on the reactor in nominal mode. In addition, an insufficiently large amount of limiting the short-circuit shock current.

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Closest to the proposed technical; The essence and the achieved result ^ is the design of a current-limiting device containing semiconductor switches and an electrical reactor consisting of a magnet duct and windings, working and control, placed on the magnetic circuit [2].

However, this device is characterized by an insufficiently large amount of limiting the short-circuit impact current, as well as a large voltage drop across the reactor in the nominal mode.

The purpose of the invention is to increase the ratio of limiting the shock current short circuit and reduce the voltage drop across the reactor in nominal mode.

This goal is achieved by the fact that a current-limiting device containing semiconductor switches and an electrical reactor consisting of an NC conductor and windings operating and control placed on a magnetic conductor contains a feedback unit connected to semiconductor keys 1 connected in series with one of

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windings, for example ,, the control winding and control winding windings are working with the same number of turns and placed on one of the magnetic cores, wherein the semiconductor switches are controlled with the windings ₅ connected in parallel and Lenia oppositely working windings.

The drawing shows a schematic diagram of the proposed device.

Current-limiting device comprises a semiconductor th keys 1 and 2 an electrical reactor, consisting of a magnetic core and windings of the working 3 and Control 4 placed on the magnetic circuit, wherein the device comprises a feedback block 5, the connected, ny ₅ to semiconductor switches 1 connected in series with one of the windings, for example, the control winding 4, the control windings 4 and the operating windings 3 are made with an equal number of turns and are placed on one ₂ θ of the cores of the magnetic circuit, with the semiconductor switches 1 with the control windings 4 I connected in parallel and counter-working windings 3.

The device works as follows.

The electric reactor is included in the cut between the source of alternating voltage and the protected device, such as a transformer. The feedback unit is connected between the transformer and the load (consumer). During normal operation, the nominal line current flows through the working windings and control windings that are connected in opposite. In this case, since the working windings and control windings are geometrically aligned in space ³⁵ (it is advisable to wind them together) and cover the same section of the magnetic circuit, their magnetic fluxes will be fully compensated. The inductive resistance of the reactor, in this case, is ⁴⁰ zero. The voltage drop at the reactor is determined only by the magnitude of the active resistance of the windings.

When a short circuit occurs in the line, the control winding is disconnected, at ⁴⁵ this instantaneous decomposition of the magnetic fluxes of the windings occurs. The magnetic flux of the working winding increases dramatically. This process occurs under conditions that differ from pure on and off inductances, as the switching of magnetic fluxes occurs. Moreover, the initial condition for switching is that the inductive resistance of the windings at the initial moment of switching is always equal to or close to zero. The latter limits the process of switching windings in time. Switching the windings of the reactor is carried out using semiconductor switches controlled by voltage feedback.

Analysis of the operation of the proposed current-limiting device shows that the reactor limits the current during the half-period to the nominal value, which is determined by the parameters of the reactor. The multiplicity of the shock current in this period of time is limited to a value of about five times.

Claims (1)

Claim A current-limiting device containing semiconductor switches and an electric reactor consisting of a magnetic core and windings, operating and control placed on a magnetic circuit, characterized in that, in order to increase the frequency ratio of limiting the shock short-circuit current, reduce contains a feedback unit connected to semiconductor switches connected in series with one of the windings, for example, the control winding, the control windings and workers bmotki formed with an equal number of turns and placed on one of the magnetic cores, wherein the semiconductor switch to the control windings connected in parallel and oppositely working windings.