SU1410161A1 - Maximum-current relay - Google Patents

Abstract

The invention relates to the field of electrical engineering, namely to devices for current protection of power lines from short circuits. The purpose of the invention is to improve the reliability of the protection against short circuit current by increasing the speed. For this purpose, a device for rectifying a brake signal is inputted to the device, the output of which is connected via an integrator to an additional input of a level indicator, which is designed as an adder of reference, operating and brake signals. Due to the inclusion of an integrator in the brake signal channel, the speed of the relay increases. 2 Il.

Description

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The invention relates to electrical engineering, namely, relay protection and automation of power systems and, in particular, to devices for current protection of transmission lines against short circuits.

The aim of the invention is to increase the reliability of the protection against short-circuit current by increasing the speed.

FIG. I shows a block diagram of the overcurrent relay; in fig. 2a, b are time diagrams of work.

The outputs of the intermediate current transformer 1 (Fig. 1) are connected to the inputs of blocks 2 and 3 of the brake and working signals rectifying, respectively, the integrator's input of 4 signals is connected to the output of the block 2 of rectifying the brake signal, and the inputs of the level indicator, made as three inputs, connected to the outputs of the EN reference signal source, integrator of 4 signals and block 3 of rectifying the operating signal, the output of level 5 indicator is connected to the input of the reacting authority 6, and the output of the reacting authority 6 is connected to the output of b Lock 7.

The overcurrent relay operates as follows .25

In the absence of an input current I, the voltage at the outputs of the transformer 1 and blocks 2, 3 is absent, while under the action of the source of the reference voltage E, the level indicator 5, the reacting body 6 and the output unit 7 are in an inoperative condition.

When the input current exceeds the current setting of the current relay, a rectified operating voltage of one character is formed at the output of the rectifier 3 of the operating signal, and a signal of a different sign at the output of the braking rectifier 2. The braking signal is integrated by the integrator 4 signals. Using indicator35

is provided at the time tcp when the voltage Uc exceeds the reference voltage Uon, while the output of the output unit 7 forms a voltage UBUX, indicating that the current relay is activated. FIG. 26 for comparison, a time diagram of the operation of the prototype device is shown. It can be seen from this diagram that with the same input current 1p, the response time of the prototype relay significantly exceeds the response time in the diagram of FIG. 2a

When the input current of a large multiplicity is disconnected (for example, equal to 250 with respect to the operation current) with an unfavorable tripping phase, the own aperiodic component of the intermediate current transformer may occur when the current IP decreases exponentially. At the same time, however, the amplitude of the aperiodic component of the operating current IP is less than the total value of the reference and braking currents 1op + 1t, so the return time of the current relay is significantly reduced and is determined only by the return time of the reacting organ.

Thus, due to the introduction of a brake signal with a lag in time and the subsequent summation of the working, brake and reference signals, a significant increase in the speed of the current relay is provided, both when the relay is triggered and when it returns, thus achieving its goal.

Claims (1)

Invention Formula Overcurrent relay containing an intermediate current transformer with an input terminal for connecting a controlled current to the circuit, an operating signal rectifier connected to the output of the intermediate current transformer, a level 5 rectifier output providing a comparison of the operating signal of the operating signal connected to the pert current 1 with the sum the reference Ion and the brake IT currents (Fig. 2a), where the current bn is proportional to the reference voltage Uon. When the amplitude of the working signal IP exceeds the sum 1op- | -1t, a positive voltage is generated at the output of level 5 indicator, and if there is no excess, a negative value is generated. With the aid of the reacting organ 6, the duration of the pulses, equal to the time of excess, is compared with the duration of the pulses equal to the absence of this excess. In this mode, the presence of positive pulses over the duration of negative pulses is ensured, and the reacting organ b is activated. Triggering reactive organ b 45 50 level input input, to the second input of which the reference signal source is connected, the reacting organ connected to the output of the level indicator, the output unit connected to the output of the reacting organ, signal integrator, characterized in that, in order to improve the reliability of the short-circuit current protection circuit by increasing the speed, a brake signal rectifier is additionally introduced, and the level indicator is provided with a third input, the brake signal rectifier input is connected to the output of the current transformer, and the output through a series-connected signal integrator is connected to the third input of the level indicator. 0 0 five five is provided at the time tcp when the voltage Uc exceeds the reference voltage Uon, while the output of the output unit 7 forms a voltage UBUX, indicating that the current relay is activated. FIG. 26 for comparison, a time diagram of the operation of the prototype device is shown. It can be seen from this diagram that with the same input current 1p, the response time of the prototype relay significantly exceeds the response time in the diagram of FIG. 2a When the input current of a large multiplicity is disconnected (for example, equal to 250 with respect to the operation current) with an unfavorable tripping phase, the own aperiodic component of the intermediate current transformer may occur when the current IP decreases exponentially. At the same time, however, the amplitude of the aperiodic component of the operating current IP is less than the total value of the reference and braking currents 1op + 1t, so the return time of the current relay is significantly reduced and is determined only by the return time of the reacting organ. Thus, due to the introduction of a brake signal with a lag in time and the subsequent summation of the working, brake and reference signals, a significant increase in the speed of the current relay is provided, both when the relay is triggered and when it returns, thus achieving its goal. Invention Formula An overcurrent relay containing an intermediate current transformer with an input terminal for connecting a controlled current to the circuit, an operating signal rectifier connected to the output of the intermediate current transformer, a working signal rectifier output connected to an alternator 0 level input input, to the second input of which the reference signal source is connected, the reacting organ connected to the output of the level indicator, the output unit connected to the output of the reacting organ, signal integrator, characterized in that, in order to improve the reliability of the short-circuit current protection circuit by increasing the speed, a brake signal rectifier is additionally introduced, and the level indicator is provided with a third input, the brake signal rectifier input is connected to the output of the current transformer, and the output through a series-connected signal integrator is connected to the third input of the level indicator. and wyk Off T FIG. i Srig.G.