SU1304120A1 - Device for short circuit protection of buses - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to electric power industry, namely, to relay protection devices. The purpose of the invention is to increase the reliability of the device. The goal is achieved by introducing into the ycTjioiicTBO control reed switches 1, 2 according to the number of controllable phases, two ems of items MEMORY 19, 20. Disconnection, any one action does not affect the protection operation, since the contacts of the reed switches 1, 2 the lines remain closed, as in load mode. In the event of a break in the control windings of 3, 4 reed switches, as well as in the chains connecting them with the source NOSTOYNN01 O of current 7, the protection is removed from operation. At the same time, the corresponding inputs of the And 25, 26 elements are not given a signal from the repKoiia 6 contacts. When the indicated reed switches 6 are in good condition, the reed switch 6 is in the active state. In the event of a break in the winding 3 n. 4, the resistance of the circuit increases, the current in the winding 5 decreases, and the contacts of the reed switch 6 open. 2 and, |. e (L with about 4 to Oh

Description

FIELD OF THE INVENTION The invention relates to electric power industry, namely, to relay protection devices.

The purpose of the invention is to increase the reliability of the device.

FIG. 1 shows a functional diagram of the proposed device; in fig. 2 - magnetic flux acting on the device reed switches.

The device contains conventional reed switches 1 and 2 with control windings 3 and 4, which are connected in opposite direction through the winding 5 of the controlling reed switch 6 to the source 7 of the operating direct current. FIG. Figure 1 shows the control windings of the reed switches and the controlling reed switch for line 8 only. In the reed switches of the other lines, they are connected in the same way (not shown). The reed switches 1 and 2 are installed in the magnetic field of the conductors of the same phases of lines 8-10 with switches 11-13 that connect the lines to the buses 14. The contacts of the reed switch 1 (2) are connected to the AND – NE 15 (16) logic element and through logical the elements are NOT 17 (18) and the MEMORY 19 (20) to the element OR is NOT 21 (22). Element 15 (16) through element MEMORY 23 (24) is connected to element AND 25 (26), to which contacts of the controlling reed switch 6 are connected, and element And 25 (26) through element TIME 27 (28) - to executive body 29, acting on the opening of the switches 11 -13.

The device works as follows.

In the load mode, the contacts of the reed switches 1 and 2 are closed, as the reed switches are actuated by the magnetic flux Fu (Fig. 2) created by the control winding current. From FIG. 2 shows that for this it is necessary that

Fu - F „,

where is FFWF, Fer is the magnetic flux in

in the winding of the control of the reed switch, in which it is triggered;

KB - reed switch return coefficient; Kj - safety factor

(K., 2-1.3); FnA is the amplitude value of the magnetic flux F5 acting on the reed switch from the conductor side at the nominal load of the latter.

Since the contacts of all the reed switches are closed, there are no signals at the output of the AND-HE elements 15 and 16 and, as a result, there are no signals at the output of the And 25 and 26 elements. Executive body 29 does not work. In case of fault on tires 14, the contacts of reed switches 1 of all the same-named line phases fall off in one of the half-periods, and in the other -

reed switches 2. Rejection of the reed switch 1 occurs in the negative half-wave when the magnetic flux, 1 (Fig. 2a) compensates for Fu, and during the time ti the reed switch is in a falling off state. At high short-circuit currents, the time of dropping of the reed switch can be insignificant, since after dropping off for the time ta it is triggered again. Therefore, this fall-off is memorized (by 0.004-0.005 s) with the help of elements 17, 19 and 23. The reed switch 2 in this half-wave remains in the activated state (Fig. 26). As a result, a signal appears at the output of element 23, the signal at the output of element 22 is already present and the actuator 29 is triggered. Similarly, the contacts of the reed switches 2 fall into the positive half-wave, and the contacts of the reed switches 1 remain in the actuated state. Now there are signals at the output of element 24 and element 21. With an external short circuit, for example, on line 8, the reed switch 1 of this line and the reed switch 2 of the line that feeds the short-circuit, for example, line 9, disappears. 15 a signal appears which is memorized by element 23 and is fed to element AND 25. However, the actuator does not work, since there is no signal at the output of element 22 (the signal is removed when the reed switch 2 of line 9 falls off). The TIME element 27 (28) has a delay of 0.002-0.003 s, taking into account the possibility of non-simultaneous opening of the contacts of the specified reed switches.

Disabling any of the lines is not in. It seems that the contacts to the reed switch of this line remain closed as in the load mode. The break in the winding of the control of the reed switch, as well as in the circuits, connecting them to the source; the right of the current and the gap is removed from operation (the corresponding inputs of the elements 25, 26 are not signaled from the contacts of the reed switch 6) and malfunctions (alarm circuits not shown). When these circuits are in good condition, the reed switch 6 is in the actuated state. When the break in the winding 3 or 4 is increased, the resistance of the circuit increases (about 2 times), the current in the winding 5 decreases, and the contacts of the reed switch 6 open.

Claims (1)

Invention Formula A device for bus protection from short circuits, containing magnetically controlled elements located in areas of a magnetic field extending from busbars of conductors, the first and second logic elements ILN - NOT, connected by outputs to the inputs of the first and second elements And, respectively, the actuator and a source of constant operating current, characterized in that, in order to increase reliability, it additionally introduces monitoring reed switches for the number of controlled phases leaving the current busbars, two MEMORY elements as well as two elements NOT and two elements MEMORY for each controlled phase of each of the outgoing conductors, two elements of TIME and two NAND elements, and the magnetically controlled elements are made for each controlled phase of each of the outgoing conductors in the first and second reed switches with control windings oppositely connected to the source of direct operating current through the control winding of the corresponding control reed switch, the contacts of the control reed switches are connected to the inputs of the first and second elements ents And, contacts of the first reed switches magician FNA / 1VL nitroplanded elements are connected to the inputs of the first NAND element, as well as through serial circuits from one element NOT and one MEMORY element to the inputs of the first element OR NOT, the contacts of the second reed switches of the magnetically controlled elements are connected to the inputs of the second element NAND, and also through successive circuits from one element NOT and one element MEMORY to the inputs of the second element OR - NOT, the output of the first element is NAND through the MEMORY element connected to the input of the second element AND, the output of the second element NID through the MEMORY element - input of the first AND gate, outputs of first and second AND gates, respectively, through first and second elements are now connected to the actuator body. ; Compiled by V. Plotnikov Editor L. Veselovska Tehred I. VeresKorrektor A. Zimokosov Order 1320/54 Circulation 619 Subscription VNIIPI USSR State Committee on Inventions and Discoveries  l 13035, Moscow, F-35, Raushsk nab., 4 / O Production-full-graphic approach, Uzhgorod, ul. Design. four