RU1810924C - Device for monitoring differential protective circuits - Google Patents

Abstract

The invention: the additional introduction of threshold blocks of the second and third phase with the memory circuit at the output, the memory circuit of the triggering of the threshold block of the first phase, the starting block of the time relay with the return circuit, the memory block of the operation of the device with the return circuit, set point, test control key, radiator and diode allows you to increase the efficiency of the control. 1 ill.

Description

The invention relates to electrical engineering and can be used in relay protection circuits of electrical equipment with the aim of monitoring the health of current circuits of differential protection, as well as bringing these protection out of action when a malfunction occurs in current circuits. The purpose of the invention is to increase the effectiveness of control.

A schematic diagram of the device is shown in the drawing.

The device contains signal converters according to the number of phases 1,2,3, threshold blocks 4,5,6 of the first, second and third phases with memory circuits for triggering the output 7,8,9, respectively, element OR NOT 10, time relay 11, element alarm 12, the operating current source + Ep 13, the Executive block 14, block 15 remembering the operation of the device with the return circuit, block 16 test control, return circuit 17, resistors 18, 19, diode 20. Threshold unit 4 consists of a matching transformer 21, diode 22 storage capacitor 23, comparator, made of an operational amplifier with inputs rezigtorami 24-26 and resistors

positive feedback 27, 28, a limiting resistor 29, and a diode 30.

The threshold unit 5 comprises a matching transformer 31, a diode 32, a storage capacitor 23. A comparator made on an operational amplifier with inputs of resistors 34-36 and positive feedback resistors 37, 38, a limiting resistor 39, and a diode 40.

The threshold unit 6 consists of a matching transformer 41, a diode 42, a comparator storage capacitor 43 made on an operational amplifier with input resistors 44-46 and positive feedback resistors 47, 48 with a limiting resistor 49 and a diode 50.

The trigger memory block of the first phase threshold block 4 consists of an RS flip-flop 51 with a resistor 57 connected to the S-input and connected to the inverse output by a series circuit consisting of a resistor 53 and an LED 54.

The trigger memory block of the threshold block 5 of the second phase consists of an RS flip-flop 55 with a resistor 56 connected to its S-input, and to its inverse output

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a series circuit consisting of a resistor 57 and an LED 58.

The actuation memory of the threshold unit 6 of the third phase consists of an RS flip-flop 59 connected to its S-input by a resistor 60, and to its inverse output by a series circuit consisting of a resistor 61 and an LED 62.

The return return 17 consists of a capacitor 63 and a resistor 64.

The time relay 11 consists of a transistor 65 to the base of which a resistor 66 is connected, a resistor 67 connected in series and a diode 68 a capacitor 69, a resistor 70 is connected in the emitter circuit of the transistor 65, to which the input of the inverter 71 is connected.

The memory unit of the triggered device with the return circuit 15 consists of a trigger 72 to the R-input of which a resistor is connected. 73, a capacitor 74 and a Reset button 75.

The Executive unit 14 consists of a transistor 76 with resistors 77, 78 connected to its base of the collector-resistor 79 and a relay coil 80.

The test control unit 16 consists of a series-connected resistor 81, a diode 82, a diode 83 and a resistor 84, as well as a Control button 85 connected to the anode of the diode 83,

In normal operation, on the controlled windings of the output organs of the differential unbalance voltage relays are small and, therefore, the voltage on the storage capacitors 23, 33 or 43-, determined by the amplitude value of the unbalance voltage (by choosing a capacitor charge time much less than time of its discharge), less than the setting of threshold blocks defined by diode 82 and resistors 25, 35, 45 for threshold blocks of the first, second and third phases, respectively. The signal at the output of blocks 1, 2, 3 is determined by the voltage of the positive limitation of the operational amplifiers 4, 5, 6.

This leads to the formation of high-level signals at the S inputs of the triggers 51.55.59. Considering that at the R-inputs of these triggers after the end of the charge of capacitors 63.74 there is a high level of potential, the triggers will be in the state that was obtained when the operational power was applied, i.e. low state

potential on a direct exit.

Since all three inputs of the OR-NOT 1057 element receive high-level signals, a low-level signal will be present at its output. This in turn causes the opening of diode 68, which ensures

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There is a low voltage level on the capacitor 69, the voltage at the input of the inverter 71 coming from the output of the emitter follower on the transistor 65 will also be small, which causes a high level of potential at the output of the inverter 71. Since high level signals are present at both inputs of flip-flop 72, the signals at their outputs have values formed at the moment of supplying operational power, i.e. low potential at the direct output and high potential at the inverse. These signal levels provide the closed state of transistor 76 and, accordingly, the presence of relay 80 in the tripped state, as well as the absence of light signaling on LED 12.

The implementation of the circuit of the device, in which its output relay is in the normal state in the tripped state, provides control over the presence of the operating current of the controlled differential protection, since the proposed device receives power from the same busbars of the operating current as the controlled protection.

If a malfunction occurs in the current circuits of the differential protection, the unbalance on the winding of the output organ of the corresponding differential relay of this protection increases and one of the threshold blocks is triggered (4-6). A negative polarity signal is generated at the output of the operational amplifier of the triggered unit, which leads to the appearance at the p-input of the corresponding trigger (51, 55 or 59), as well as at the corresponding input of element 10, a low level of potential coming through one of the resistors - 52 56 or 60 (depending on the output of which of the operational amplifiers 4, 6 or 6, the negative polarity signal is supplied). The appearance of these signals causes a corresponding trigger to be flipped and a low level voltage to be installed on its inverted output and a light signal will appear (one of the LEDs 54, 58 or 62 is working), as well as a high level of the output of the OR-NOT 10 element potential. The latter causes the discharge of the capacitor 63, as well as the closure of the diode 68 and the beginning of the charge of the capacitor 69 from the positive polarity power supply with a constant time determined by the values of the resistor 66 and the capacitor 69. The voltage across the resistor 72 will repeat the voltage capacitor 69 (an emitter follower on transistor 65 is introduced to prevent the inverter 71 from affecting the charging process of capacitor 69). The inverter 71, made on the integrated circuit K511LA1, has a switching threshold of about 7.2 V. When the voltage value is reached at the resistor 70 of this level, the inverter 71 switches, the output of which produces a low-magnitude signal, which triggers the trigger 72 and appears on its direct output is high, and on the inverse, low levels of potential. The signal from the inverse output through the diode 20 is fed to the third input of the element OR NOT 10. ensuring that this circuit is in the state of the logic unit by the output, regardless of the state of the threshold blocks, this ensures the discharged state of the capacitor 63 and the preparation of the return of triggers 54, 55 , 59 to the initial state when the reset button 75 is pressed. At the same time, the LED 12 provides a light signaling that the device has been triggered, which can also be removed only with the reset button 75. A high level signal coming from the direct The output of the trigger 72 through the resistor 77 to the base of the transistor 76 causes the latter to open, bypassing the winding of the relay 80 and its operation (the triggered state of the relay in this circuit is considered to be the state when the coil is de-energized). The relay, which operates, performs the necessary switching in the external circuits and remains in this position, regardless of the state of the threshold organs, until the circuit returns to its initial state using the Reset button 75. This execution allows the differential protection of the object to be output with simultaneous introduction of backup protection (for example, non-selective cut-off), which allows you to keep the transformer in operation and at the same time provide its reliable (taking into account the presence of gas protection) protection.

When the button 75 (Reset) is pressed, a low-level signal is sent to the R-input of the trigger 72, which causes the flip-flop of the trigger 72 and a low-level signal at its direct output, and a high-level signal at the inverse output. As a result of the high potential level at the inverted output of flip-flop 72, LED 12 goes out and diode 20 closes. A low potential level at the direct output of flip-flop 72 closes transistor 76 by energizing relay 80 and returning it to its original position. If the threshold blocks of device 4-6 are in a non-working state, then the appearance of a logic unit signal at the inverse output of flip-flop 72 causes the element 10 to switch to a logic-zero state at the output, which causes a short-term (due to charging of the capacitor 63) phenomenon on the R-inputs of the triggers 51. 55. 59 5 signals of logical zero and the installation of these triggers in the initial state.

Test control is carried out by pressing the Control 85 button. In this case, the inputs of the first, second, third threshold 0 blocks through resistors 24, 34, 44 respectively receive a signal that is known to be larger than the settings, which leads to their operation and the formation of light signals using LEDs 54, 58 , 62. If the button is held for a long time (more than the setting and the time relay), the device as a whole will be triggered and the light indication of this state will be formed using the LED 12.

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Claims (1)

SUMMARY OF THE INVENTION A device for monitoring differential protection circuits comprising phase-to-phase signal converters to an output 5 of the first of which a threshold block of the first phase is connected, an OR-NOT element, to the output of which a time relay, an alarm element, an operating current source and an executive block are connected, characterized in that, in order to increase the monitoring efficiency, threshold thresholds are additionally introduced blocks of the second and third phase with memory circuits for triggering the output, memory circuit for operating the threshold block of the first phase, memory block for triggering the device with a reset circuit, test control unit, reset circuit, two resistors an ora, a diode, while the first inputs of the threshold blocks of the second and third phases are connected to the outputs of the second and third signal converters, respectively, the memory circuit of the operation of this block, the outputs of the circuits are connected to the output of the threshold block of the first phase 5 memories are combined and connected to the positive terminal of the operating current source. The second combined inputs of the threshold phase blocks are connected to one of the inputs of the test control unit, 0 third inputs of which are combined and connected to the output of the test control block, connected between the negative terminal of the operating current source and the combined ones. memory circuit outputs 5 triggering threshold blocks, the second inputs of which are combined and connected to the middle terminal of the return circuit, which is connected between the positive terminal of the operating current source and the output of the ILI-NOT element, between the third input of which the first resistor is connected by the output of the threshold block of the third phase, the outputs of the threshold blocks of the first and second phases respectively are connected to the first and second inputs of the element OR, the output of the time relay is connected to the input of the memory unit of operation of the device with a return circuit whose inverse output is through the diode, turned on in the opposite direction, connected to the third input of the OR-NOT element and through a second resistor and an alarm element connected in series with the positive terminal of the operating current source, the direct output of the specified block is connected to the input of the executive unit, the power supply terminals of which, as well as the memory of the operation of the device with the return circuit and the time relay are connected to the positive terminal of the operating current source .