SU851525A1 - Self-restoring current limiter - Google Patents

Description

(54) SELF-RECOVERY LIMITER The invention relates to electrical engineering, and more specifically to electrical appliance building, and can be used in conjunction with a low-voltage circuit breaker to turn off very large short-circuit currents when the limit mutation ability of the switch is insufficient. Self-repairing current-limiting devices are known, based on the effect of a magnetic field created by a coil-inductor-torus on a jumper from a liquid metal enclosed between solid metal electrodes, resulting in the ejection of a liquid metal into the arc chute and limiting the current of the protected circuit 1. Nf1 residues This technical solution is the DIFFICULTY of the design (the presence of the inductor coil and its sensor) and the reliability of the work is not high enough. Closest to the present invention is a self-healing current limiter containing an insulated sealed enclosure, an arcing device and two solid metal armatures are installed inside

CURRENT Electrodes, forming together with a liquid metal jumper, a U-shaped loop loop. In the known device, the electrodes are oriented vertically, and the liquid metal jumper is located on the top and closes the ends of the electrodes 2. A disadvantage of this device is the low speed due to the non-oriented execution of the loop U-shaped loop. The purpose of the invention is an increase in speed due to an increase in the effect. The goal of the loop is to ensure that the self-restoring current limiter contains an insulated sealed enclosure, inside which is installed an arcing device and two solid metal electrodes forming a D-shaped loop loop with the liquid metal jumper. The electrodes forming the specified circuit are horizontally arranged, and a liquid metal jumper is installed in the middle of the upper electrode. The drawing shows the proposed construction of a self-healing current limiter.

The self-restoring current limiter contains solid metal electrodes 1 and 2 / bridged with liquid metal 3 (for example, potassium and sodium alloy), an arcing device 4, and arcing horns 5 located in a hermetically sealed removable insulating chamber b filled with an inert gas (for example, nitrogen). Solid metal electrodes 1 and 2 are fixed horizontally at the base 7. Between electrodes 1 and 2 there is an insulating gasket 8

The opposite ends of the solid metal electrodes 1 and 2 have clamps 9 and 10 for connection to the circuit to be protected.

The length of the solid metal electrodes 1 and 2, the size of the jumper from the liquid metal 3 between them, as well as the thickness of the insulation strip 8, are determined by the requirements of the current limit and can vary within the required limits.

In order to increase the strength, the insulating chamber 6 is enclosed in a robust protective casing 11 and may have an opening in its upper part for the installation of a safety valve (not shown).

The device works as follows.

With the passage of the nominal current in the protected circuit along the contour 102-3-1-9, the electrodynamic effect of the lower part of the current loop cb on the upper part of the circuit with the liquid metal 3 (jumper) is slightly and balanced by the weight of the liquid metal.

The whole system is in a state of stable equilibrium. At occurrence of current short circuit in the circuit to be protected, the electrodynamic effect of the lower part of the current circuit Q on the jumper from liquid metal 3 increases tenfold, the equilibrium is disturbed and the liquid metal 3 is immediately ejected up into the arc chamber 4.

The electric arc arising between electrodes 1 and 2 is stretched on arcing horns 5 and acquires considerable resistance in the arcing chamber 4, limiting the short-circuit current, and the circuit breaker disconnects the protected circuit at this time.

ndcne disconnect current k.z. an automatic switch, the liquid metal 3 returns to the interelectrode space under the action of a neutral weight, restoring a U-shaped circuit. The time during which there is no liquid metal 3 between electrodes 1 and 2 is always longer than the full time of the circuit breaker to operate, because before the circuit is completely disconnected

the liquid metal 3 will be affected by the electrodynamic forces of the lower part of the current loop a, directed oppositely to the gravity of the liquid metal 3.

Therefore, the circuit between the electrons 1 and 2 during the period of the short circuit current. a circuit breaker cannot occur, i.e. the circuit breaker will always disconnect the protected circuit at a limited value of the short-circuit current.

Since the electrodynamic forces between parallel conductors are inversely proportional to the distance between them, and in the proposed

5 the distance between the section of the current loop Q and the section c formed by the liquid metal 3 may be very small, this dramatically increases the electrodynamic effect

Q devices

An increase in the electrodynamic effect due to a decrease in the distance between the interacting parts a and c makes it possible to obtain large electrodynamic forces in a small volume, which in turn significantly reduces the size of the device and, consequently, its mass.

The horizontal arrangement of the U-type electrodynamic contour with the electrodynamically interacting areas Q parallel to the active and active and allow to create a more compact and stable device design.

The proposed device is very simple in terms of the design and production, it works automatically and autonomously, has small dimensions and weight, is highly reliable and can provide both economic production and operation.

The device can be used in electric circuits with very high short-circuit currents, when the limit on the switching capacity of the switch for these circuits is insufficient.

Claims (2)

1. USSR author's certificate No. 607291, cl. H 01 H 29/30, 1978. 2. USSR author's certificate on application 2729391 / 24-07, hl. H 01 H 29/30, 1979. eleven p L rt V t //////////////////// ///////////////////. .