SU748625A1 - Current limiting device - Google Patents

Description

(54) CURRENT LIMITING DEVICE

I

The invention relates to electrical engineering and can be used in systems that supply power to energy-intensive consumers, where a reduction in the level of short-circuit currents is required.

Known current-limiting devices containing odionic and twin reactors connected in series to current circuits (1. However, reactors permanently connected to the operating current circuit and possessing significant inductive resistance, cause a large amount of voltage loss and reactive energy.

The closest to the invention by technical nature is a device for limiting short-circuit current 2, which contains a cylindrical winding, inside which during a short-circuit a ferromagnetic core is pulled in, providing an increase in the inductance of the reactor winding.

However, this device has a high inertia, due to pro-, action when triggered by a power return spring. The response time also increases due to the need to tune the switch off time from the introduction of the ferromagnetic core into the reactor winding, which reduces

reliability of operation.

The purpose of the invention is to increase the speed and reliability of functioning. devices ..

This goal is achieved by the fact that

-current-limiting device containing a reactor with a movable ferromagnetic

10 with a latch core and a protection relay, connected to the input, to the measuring current transformer, and an output to the electromagnet disconnected; The switch is mounted on the latch of the ferromagnetic core.

Combining a limiting reactor with a variable resistance and a switch connected in series with a switch in series in one device allows for fast and multiple current limiting, as well as improving the reliability of the switch.

The drawing shows a functional diagram of a current-limiting device for a single phase.

In the tank 1 of the switch, a movable contact rod 2 and a fixed socket contact 3 are placed. The winding 4 of the reactor is connected in series with the switch, and the ferromagnetic sulfur is connected to the circuit; Deknik 5 is outside the winding and held in this position by the latch. A protection relay 7 is applied to the current transformer b, acting on the opening electromagnet 8 of the switch. The ferromagnetic core 5 is connected with a swivel rail 10 having a turning point II by means of a gigi 9, and the opposite end of the rail 10 is connected through an insulator to a movable contact rod 2 of the switch. In order to move the rod 2, it is connected to the current-carrying piece by means of a flexible connection.

Current-limiting device operates as follows.

In the event of a short circuit on the line, the protection relay 7 triggers and sends a pulse to the shutdown electromagnet 8. The latch is released, and the ferromagnetic core 5 is inserted along the guides into the reactor winding 4. A large insertion speed of the core 5 and a corresponding increase in the inductive resistance of the reactor winding 4 is provided by dead weight of the core 5 and the electromagnetic force of the winding 4 of the reactor.

When the core 5 moves downwards, the rail 10 rotates through the pull rod 9 and the movable contact rod 2 begins to exit the receptacle contact 3. The ratio of the arms of the L-Ij rocker arm is chosen so that while the movable contact rod 2 makes its way to the inside of the receptacle contact 3 (usually 1F 30 -35 mm), the core 5 will be introduced into the winding 4 of the reactor.

Consequently, by the time the movable contact rod -2 leaves the socket contact 3, i.e., by the time of arcing of the breaker contacts, the reactor resistance due to the introduction of the ferromagnetic core will increase at least tpn times and, accordingly, the switchable current will decrease . The presence of a slot in the lower part of the rod 9 and the possibility of its rotation allow the left end of the rail 10 with the movable contact rod 2 to move upwards without any obstacles.

As the switch is actuated, the ferromagnetic core 5 is raised.

.:.

-.: .., Or, ... f: .., l:, f -: ..,. -in the original position and the device is ready for re-action.

A variation of the device can be a combination of a switch with a cargo drive and a current-limiting reactor with variable resistance - the role of a ferromagnetic serpentine can be performed by a load-carrying drive. The return of the load (core) to the initial upper position is carried out as in conventional switches with a load-operated drive, i.e. manually or

using an electric motor with a worm gear.

The technical and economic efficiency of the device, where the switch and the current-limiting reactor with variable resistance are combined, is determined by the fact that by increasing the speed of the short-circuit current switching off, the arc erosion of the contacts decreases, the switch overhaul interval increases, its reliability increases. In addition, the presence of a rigid connection between the moments of an increase in the inductive reactance of the reactor and the occurrence of an arc at the opening of the switch provides, on the one hand, multiple. reduced switching current and, on the other hand,

there is no need for an artificial delay of the moment when the current is turned off by a switch. This increases the reliability of the switch and allows you to select reduced cable cross-sections of the outgoing lines (along

thermal effects of short-circuit currents).

Claims (2)

1.Vasilyev A. A. Electric part of stations and substations. Part I. REI, 1963, p. 366-391. 2. USSR author's certificate number 18359, cl. H 02 H 9/02, 1926.