SU845194A1 - Apparatus for protecting from back currents - Google Patents

Description

(54) APPARATUS FOR PROTECTION AGAINST CURRENTS. CURRENTS

I

The invention relates to a technique for switching high-current DC circuits, in particular to apparatus for protection against reverse currents.

The known device for protection against reverse currents, containing an electromagnet, the measles of which is connected to a contact system, and a magnetic rotary myHt with a demagnetizing winding included in the circuit to be protected 1.

Such a device is characterized by insufficient reliability in operation, especially at elevated accelerations.

A reverse-flow protection apparatus is also known, comprising a contact system consisting of a fixed contact and a movable contact mounted in a contact holding device connected through a transmission mechanism to the switch-on electromagnet, a free disconnecting mechanism and a current direction sensor interacting with a permanent magnet 2.

This device is characterized by large dimensions, insufficient speed and low reliability, especially at increased accelerations.

The aim of the invention is to reduce the size of the apparatus and increase its speed and reliability.

This is achieved by the fact that in the apparatus the contacts are made of liquid metal, the current direction sensor is made in the form of a spring-loaded ferromagnetic bracket enclosing the contact holder and rigidly fixed on an axis passing freely through the contact holder and the measuring electromagnet, the middle part of the axis is filled with two-sided parallel slots The switch on the electromagnet of the inclusion at the point of passage of the axis is made with a figured hole, and the figured hole forms with the middle part of the axis a lock of the on position.

15 FIG. 1 shows the proposed apparatus in the disconnected position, cut; in fig. 2 - included machine in the case, general view; in fig. 3 - the same, side view; in fig. 4 - axis isometries; in fig. 5 - the position of the lock when the machine is turned on; in fig. 6 - the same, with the device turned off.

Claims (2)

The device contains a fixed contact 1 with liquid metal contacting. 384 by the elements 2 and the movable contact 3 with the liquid metal element 4. The movable contact 3 is installed with the possibility of moving with the aid of, and liquid metal lubricant 5 in the contact holder 6. The movable contact 3 is connected to the drive unit through a transmission mechanism. The transmission mechanism comprises rigidly interconnected parts 7, 8, 9, 10 of the contact pressure spring 11 and the shutdown spring 12. The drive device consists of a turn-on electromagnet 13 with a winding 14, a part (core) 9, which is part of a transmission mechanism, a permanent magnet 15 with a bias winding 16 (the device uses two permanent magnets with bias windings; see Fig. 2 ) and a free-release mechanism with a spring-loaded latch 17, made in the form of a two-arm lever, one shoulder of which is a cortex and the other shoulder is a latch. The reverse current sensor is made in the form of a ferromagnetic bracket 18 fixed on the axis 19. The axis passes through the contact holder 6 and the bark 9 and can rotate relative to the contact holder 6. The free ends of the ferromagnetic bracket 18 have bends that are attracted to the pole pieces of the permanent magnets 15 in the on position of the apparatus (Fig. 2 and 3). On the reverse side, the bracket 18 is attached to a spring 20 opposing the permanent magnets 15. The axis 19 in the middle part is made with double-sided parallel grooves (Fig. 4) and the switch 9 of the turn-on electromagnet is made with a figured hole (Fig. 5 and 6). 19 and the shaped hole of the core 9 form a lock on position. To turn on the apparatus, it is necessary to excite the winding 14 of the electromagnet 13 of the turn-on current. The winding 14 is connected in parallel with the winding of the biasing 16 of one of the permanent magnets 15. When excited by the current of the windings 14 and 16, the measles 9 of the electromagnet will begin to move up (along arrow A in Fig. 6), compressing the spring 12, all the way to the axis 19. Switching is not This will happen because when the winding 14 is excited, the free-release mechanism by one of its levers is attracted to the electromagnet 13 and the latch 17 will stop the movement of the movable contact 3 connected to the cortex 9 at some distance from the fixed contact 1 (the precursor state). At this time, one of the permanent magnets 15, as a result of the excitation of its winding 16, attracts the ferromagnetic shackle 18 and thereby shifts the axis 19 through a certain angle (Fig. 5). After this, the windings 14 and 16 are de-energized, the springs of the free-release mechanism release the latches 17 and the contact pressure spring 4 11 presses the movable contact 3 to the fixed contact 1, completing the switching-on operation and preparing the device for the subsequent shutdown. A free release mechanism is necessary to prevent the apparatus from turning on to reverse current at a time when the apparatus is not prepared for disconnection. In the on position, the device is configured to turn off the reverse current of a certain value. The magnitude of the reverse current setting is determined by the selection of the geometric dimensions and materials of the ferromagnetic bracket 18 and the permanent magnets 15. With the passage of a current of the desired polarity in the ferromagnetic bracket 18, a magnetic flux is induced, which is directed in the same direction as the flow of the permanent magnets 15. At In the case of reverse current, the magnetic flux in the ferromagnetic bracket changes direction and is directed opposite to the fluxes of the permanent magnets 15. When the reverse current reaches the setpoint value, when the attractive force of the permanent magnets 15 becomes insufficient to hold the ferromagnetic bracket 18, it rotates by the action of the spring 20. Together with the bracket 18, the axis 19 also rotates. When the grooves of the middle part of the axis 19 coincide with the shaped hole of the core 9, the spring 12 will return the moving contact 3 in the disconnected position. to disconnect, regardless of the magnitude and direction of the current in the protected circuit, it is necessary to apply a reverse polarity voltage to the winding 16 of another magnet 15. The described device is more reliable in operation, since the holding device In the switched on position, the clamp is carried out with the help of a clamp, and in the known apparatus 2 - only due to the forces of attraction of a permanent magnet. Making contacts in the form of plates, the gaps between which are filled with liquid metal, or in the form of a metal tape rolled into a spiral, with liquid metal placed between the turns of the spiral, allows not only to significantly reduce the size of the apparatus and increase its speed, but also to use a direction sensor current - ferromagnetic skOu as an executive body, as it rotates and the axis rotates, resulting in a shutdown. Claims of the Invention Apparatus for protection against reverse currents. containing a constant system consisting of a fixed contact and a movable contact mounted in a contact holder, connected through a transmission mechanism to the switch-on electromagnet, a free release mechanism and a current direction sensor, which interacts with a permanent magnet, in order to reduce overall dimensions, speed and reliability, the contacts are made of liquid metal, the current direction sensor is made in the form of a spring-loaded ferromagnetic bracket, covering the contact coder The holder is rigidly fixed on the axis, the neck passes freely through the contact holder and the measuring electromagnet of the switch-on, the middle part of the axis is made with double-sided parallel E. 1 grooves, the switch of the electromagnet of the inclusion at the point of passage of the axis is made with a figured hole, and the figured hole forms with the middle part of the axis a lock of the engaged position. Sources of information taken into account during the experiment, the tritis 1. USSR author's certificate No. 53712, cl. H 01 H 83 08, 1937. 2. USSR author's certificate number 23722, cl. H 01 H 83/08, 1965 (prototype). 16 7 / -18 19 FIG. 2 Fig.Z nineteen FIG.