SU851602A1 - Device for protecting from damage of tapped lines - Google Patents

Description

154) DEVICE FOR PROTECTION AGAINST DAMAGE The device is referred to as relay protection and is intended for use as protection for power transmission lines that run out of busbars of power plants. Devices are known for supplying lines of current and a current starting organ and a pulse relay of the direction of power fl, and a pulse current directed relay p. In these devices, the secondary winding of the measuring current transformer (CT) is connected to the primary winding of the transducer, the secondary winding of which through the short pulse shaper, which is simultaneously a current trigger body, is connected to one of the inputs of the logic circuit and through an intermediate TT and a square pulse shaper - with the second input of the circuits I. The third input of the mentioned circuit I is connected through a shaper of rectangular pulses and a direct current voltage transformer (TH) with a measuring trap with a voltage formatter. The output of the circuit And connected to the output body. The disadvantage of these line protection devices is the presence of a dead voltage zone. WASTE LINES The closest to the proposed technical essence is a device for the protection of parallel lines with a comparison of the directions of currents in them, containing current transformers by the number of lines connected through square-wave drivers with logical elements AND, elements of time and output blocks 3. However, the device does not work reliably in transient modes of short circuits and in the presence of current transformers. The purpose of the invention is to increase the reliability of operation during transient conditions and at saturation of current transformers. This goal is achieved by the fact that the device for protection against damage of outgoing lines, which contains the number of lines and the immersion current transformers connected through the square pulse shapers with the pitch of the logic elements And, and the output blocks, is additionally introduced to the trays, short pulse shapers and inverters, in the secondary circuit of current transformers transceivers are connected, connected through short pulse formers with the second inputs of the above logic elements If, remain nye vvoy which through inverters soediney with rectangular shaper E mpulsov all other than its boiling thod lines.

Figure 1 shows the structural scheme of the protection device of the three waste of their lines (the diagram is shown in the half-wave version for one phase); Fig. 2 shows timing diagrams for the operation of the device in the event of damage on the line and on the buses.

The protection device contains measuring CTs 1, the secondary windings 15 of which are connected to the primary windings of the intermediate CTs 2 and transreactors 3 in series. The secondary windings of the transreactors through starting organs, which simultaneously form 4 short pulses, are connected to the first input of the logic element 5, and the secondary windings of the intermediate CTs 2 through the formers 6 are straight-line. pulses are connected to the second input of the element I 5,

The secondary windings of the intermediate CTs 2 of the remaining (supply) connections are via pulse shapers and inverters 7 connected to the remaining 30 inputs of element AND 5. The outputs of logic elements 5 are connected to output blocks 8, which are connected to the deflection solenoids of the switches 9 of the respective connections. 35

In case of damage at one of the connections, the phase of the current of the damaged connection (Fig. 2a) differs from the phases of the currents of the rest supplying connections ij, and i by 120-180 al. The output voltage of the transreactor practically corresponds (with some error) to the first derivative of current i, i.e. proportional to the periodic component of the current. For- The globalizer 4 short-duration pulses forms from this voltage (for each half-wave) a short-term pulse that occurs practically when the voltage goes through a zero value and only if it reaches the specified setpoint. Since at the moment of occurrence of a short pulse there are rectangular pulses of the same polarity at all the other inputs of the element 5, 55 a signal passes through it leading to the operation of the output unit 8. If any supply connection is disconnected, this will not result violation of the functional stability of the device, since at the input of the element And 5, corresponding to the disconnected connection, there will be a signal equal to one.

If damage occurs on the tires (Fig. 2b), the phases of the currents of the supply connections will be in the range of 0-60 e.hladers. At the moment of occurrence of a pulse from the transreactor 3 at the inputs of the element And 5, corresponding to the other supply connections, the pulses will not be present simultaneously, and the device will not work.

When CT 1 is set, as is well known, in the secondary windings of transreactors 3 bursts may appear, resulting in the appearance of false impulses. In the proposed device, this disadvantage is eliminated by the presence of a second input of the AND circuit 5, to which a rectangular pulse is supplied from the transformer 2 of the protected connection,

The proposed protection device for determining a damaged connection does not use voltage, therefore there are no dead zones. The field of application of the proposed device is the waste from busbars having at least three feed connections.

Claims (3)

1. Fedoseev A.M. Relena protection of electrical systems. M., Energie, 1978, p. 2. Author's certificate of the USSR I 311333, cl. H 02 K 3/08, 1971. 3. Figurnov E.P. Protection of electric AC mains from short circuits. M., Transport, 1979, pp. 130-133. Vot and ltUo1 o, U vei Vji % % It Vn Jl