SU1089667A1 - Device for checking serviceability of three-phase isolated neutral system - Google Patents

Abstract

A DEVICE FOR MONITORING THE CORRECTION OF A CURRENT RELAY CABLE OF A THREE-PHASE NETWORK WITH ISOLATED NEUTT RALYO, containing the main memory element, the input of which is connected to the output of the relay protection unit in the circuit of the protected network, the direct output of the memory element is connected to the first input of the element AND health alarm OR is connected to the executive body, characterized in that, with the whole speed and reliability of the closure, additional memory elements and the AND element, the number of which is equal to the number of fa 3, each element I is provided with three inputs, one of which is connected to the direct output of the memory element of its phase, and the other two are connected to the inverse outputs of the memory elements of the other phases. (L

Description

00

with

Have

O5

J. The invention relates to the automation of power systems and can be used to monitor the health of high-speed current protection of variable-voltage power systems (EES). Nowadays, current-limiting switches, controlled by high-speed relay protection with a tripping time of not more than 0.6 ms, are widely used. That co-limiting switch is a critical element of power systems, which imposes strict requirements on the reliability of its control devices. A device for monitoring the operability of the relay protection is known, which contains an emergency imitation node connected via a switch key to a protective object and a relay protection unit (RHP), the output of which is connected to the first input of the viii node (HC) via a serially connected key in the switch and fi ; Low frequency (LPF), the second HC input is connected to the VRZ output directly, and the HC output is connected to the executive unit (BUT), which has a time delay for triggering l. This device monitors the health of the protection system as a whole, which is realized by applying an operating current to the operating current of the protected object. However, this principle is possible only in low current circuits. In high-current circuits of alternators, this device is practically unrealizable due to the complication of the emergency simulation block, as well as the increased power of the power supply and switching devices. Moreover, this device is to turn off the unit immediately after detecting its failure, which is not always possible. since the responsible installations cannot shut down when the control devices are faulty. The closest to the one proposed is a device for monitoring the operability of the relay protection, containing The actuator connected to the relay protection unit and the output element AND with the element NOT at the input. The input of the element is NOT connected to the outputs of the relay protection unit, the output of which is connected through the memory element to the input of the output element I. 6672 The output of the memory element is connected to the whip of the executive body. The device works as follows. In the event of damage to the electrical installation, the relay protection unit is triggered and the signal is simultaneously applied to the memory unit and through the item NOT to the input element output. From the output of the memory block, the signal is fed to the input of the output element I and to the executive body, which turns off the protection power from the input side. In this case, the relay protection unit returns to its initial state, and at the output of the element of the output element I, an operation signal appears. If the relay protection unit itself is damaged, the latter is triggered and does not return to its initial state when the actuator is triggered. Therefore, the signal through the elements NOT and AND passes to the output of the output element AND and the signal to turn off the electrical installation is missing Sj. A disadvantage of the known device is a delay in actuation due to a test requiring the initial actuation of a PZ and subsequent shutdown. An increase in the time from the moment of the occurrence of an accident to the formation of a disconnecting impulse is unacceptable for REs, which are quick acting on the current-limiting switch. In addition, the device is characterized by the lack of verification of the output organ, which significantly reduces the control efficiency. The purpose of the invention is to increase the speed and efficiency of control of the relay protection unit. The goal is achieved by the fact that the direct memory output of the memory element is connected to the first input to the device for monitoring the operability of a three-phase network current protection with an isolated neutral, containing the main memory element, the input connected to the output of the relay protection unit in the protected network. element of the health alarm and through the element OR is connected to the executive body, additional memory elements and AND elements, the number of which is equal to the number of phases, are introduced, each AND element is equipped with three inputs, one of otorrhea connected to a direct output of the memory element of its phase, and the other two are connected to the inverse outputs of the memory elements of other phases. When the relay protection units operate in three-phase systems without neutral, the short circuit is accompanied by the operation of the two relay protection units. The operation of one block of relay protection but .. but be regarded as a false trigger or failure to trigger one of the blocks of relay protection. Therefore, in the proposed device, testing of one channel is carried out by another channel. The drawing shows a functional diagram of the proposed device. The device in each channel contains an AND 1 element, the first input of which is connected to the direct output of the memory element, for example, trigger 2, and the second and third inputs to the inverse trigger codes 2 of the two other channels. The trigger input 2 is connected to the output of the relay protection unit 3 and the inputs of the element OR 4. The outputs of the elements OR 4 and 5 are connected to the input of the executive body 6, and the inputs of the element OR 5 are connected to the outputs of the channel elements AND 1. The device operates as follows. When two relay protection units are triggered, the corresponding memory elements 2 are set to one state, which leads to the fact that there are no signals at the outputs of the And 1 elements. The shutdown of the protected device is carried out by the executive body, which is triggered through the element IL1 4. If one of the relay protection units 3 fails, the executive body 6 is activated by shutting down the protected installation. At the same time, one of the memory elements 2 is triggered and at the output of one of the elements I 1, a signal appears which, through the element OR 5, enters the input of the actuator to signal the failure of one of the relay protection blocks. The selection of a specific unworked relay protection unit can be made according to the state of memory elements 2. One of the elements 2 of the memory, which is in the zero state, corresponds to the failed operation of the re-. line protection. The proposed device carries out a functional test of the relay protection and signals it. In addition, there is no testing, test signal, and the test is performed by monitoring the channel response. The device allows the verification of all blocks, including the output. The control operation does not deactivate the blocks and elements of the proposed device, which increases its additional reliability, since the control unit performs work in parallel with the execution of the main function of the device and does not affect its elements.

| Гртщтгт --Дщ;

 t.

Claims (1)

DEVICE FOR MONITORING THE PROPERTIES OF CURRENT RELAY PROTECTION OF A THREE-PHASE NETWORK WITH ISOLATED NEUTRAL, containing the main memory element, the input of which is connected to the output of the relay protection unit in the circuit of the protected network, the direct output of the memory element is connected to the first input of the And signaling unit of health and through the OR element is connected to organ, characterized in that, in order to increase the speed and reliability of control, additional memory elements and AND elements are introduced into it, the number of which is equal to the number of phases, each AND gate has three inputs, one of the cop ryh connected to the direct output of its phase memory element, and the other two are connected to the inverse outputs of the memory elements of other phases. >