SU1267522A1

SU1267522A1 - Device for current fault protection in a.c.network

Info

Publication number: SU1267522A1
Application number: SU853903739A
Authority: SU
Inventors: Валерий Ефимович Райнин; Валентин Леонидович Карась; Янна Михайловна Михлина
Priority date: 1985-05-29
Filing date: 1985-05-29
Publication date: 1986-10-30

Abstract

Изобретение относитс к устройствам защиты, в частности к блокам полупроводйиковых максимальных расцепителей низковольтных автоматических выключателей. Целью изобретени вл етс повышение надежности устройства . Цепь достигаетс путем введени в схему двух последовательно и согласно соединенных диодов И и 12, транзисторного ключа 13 с транзистором управлени 14 и резисторов 15,16, 17, что дает возможность обеспечить симметричную работу трансформаторов тока в оба полупериода первичного тока и тем самым устранить токовую погрешность трансформаторов тока, св занную с несимметрией, за счет ис- Q пользовани единственного стабилитро- ® (Л на, повысить чувствительность защиты от однофазных коротких замыканий, а следовательно, надежность защиты по сравнению с прототипом. 1 ил.The invention relates to protection devices, in particular, to semiconductor maximum release units of low-voltage circuit breakers. The aim of the invention is to increase the reliability of the device. The circuit is achieved by introducing into the circuit two in series and according to connected diodes I and 12, transistor switch 13 with control transistor 14 and resistors 15,16, 17, which makes it possible to ensure symmetrical operation of current transformers in both half-periods of the primary current and thereby eliminate the current error current transformers associated with asymmetry, due to the use of a single stabilizer ® (L on, to increase the sensitivity of protection against single-phase short circuits, and therefore the reliability of protection vneny the prototype. 1 yl.

Description

Изобретение относится к устройствам защиты от перегрузок, междуфазных и однофазных коротких замыканий, обрыва фазы, в частности к блокам полупроводниковых максимальных 5 расцепителей низковольтных автоматических выключателей.The invention relates to devices for protecting against overloads, interphase and single-phase short circuits, phase failure, in particular, to semiconductor blocks with a maximum of 5 releases of low-voltage circuit breakers.

Цель изобретения - повышение надежности в работе устройства.The purpose of the invention is to increase the reliability of the device.

На чертеже изображена схема пред- ¹⁰лагаемого устройства.The drawing shows a diagram of pre- ¹⁰ Laga device.

Устройство содержит трансформаторы 1 тока, включенные в каждую фазу защищаемой сети. Начала вторичных обмоток трансформаторов 1 тока через *⁵измерительные резисторы 2 включены в звезду, а концы через силовой выпрямитель 3 подсоединены к накопительным конденсаторам 4. Параллельно выходу выпрямителя 3 подключена цепь тиристор 5 - катушка 6 электромеханического исполнительного органа. С каждого накопительного конденсатора 4 снимается питание положительной и отрицательной полярности относительно 25 общей точки для органа 7 контроля тока. Симисторы 8 подключены катодами к входным зажимам силового выпрямителя 3, управляющими электродами - к входным зажимам маломощного 30 выпрямителя 9 управления, анодами к общей точке измерительных резисторов 2 и накопительных конденсаторов 4 - общей точке схемы. К входным зажимам маломощного выпрямителя 9 35 подключен задающий стабилитрон 10, зашунтированный цепочкой из двух последовательно и согласно включенных диодов 11 и 12, через транзис:тор 13 ключа. Транзистор 14, управляющий транзистором 13 ключа, подключен коллектором через резистор 15 к базе транзистора 13 ключа, базой через резистор 16 - к точке соединения катодной группы выпрямителя 9 управ- 45 ления и эмиттера транзистора 13 ключа, через резистор 17 - к точке соединения анодной группы выпрямителя 9 управления и диода 12. Диод 18 ' подключен встречно-параллельно ба- 59 за - эмиттерному переходу транзистора 14 управления. Резистор 19 шунтирует база - эмиттерный переход транзистора 13.The device contains current transformers 1 included in each phase of the protected network. The beginnings of the secondary windings of current transformers 1 through * ⁵ measuring resistors 2 are connected to the star, and the ends are connected to the storage capacitors 4 through the power rectifier 3. A thyristor 5 circuit is connected in parallel with the rectifier 3 output - coil 6 of the electromechanical actuator. From each storage capacitor 4 is removed the power of positive and negative polarity relative to 25 common points for the body 7 of the current control. Triacs 8 are connected by cathodes to the input terminals of the power rectifier 3, the control electrodes to the input terminals of the low-power control rectifier 9, the anodes to the common point of the measuring resistors 2 and storage capacitors 4 to the common point of the circuit. To the input terminals of a low-power rectifier 9 35 is connected a master zener diode 10, shunted by a chain of two in series and according to the included diodes 11 and 12, through a transization: key 13 torus. The transistor 14, which controls the key transistor 13, is connected by the collector through the resistor 15 to the base of the transistor 13 of the key, the base through the resistor 16 to the connection point of the cathode group of the rectifier 9 of the control and emitter of the transistor 13 of the key, through the resistor 17 to the connection point of the anode group the control rectifier 9 and the diode 12. The diode 18 'is connected counter-parallel to the base 59 for the emitter junction of the control transistor 14. The resistor 19 shunts the base - the emitter junction of the transistor 13.

Устройство работает следующим об- ₅₅разом,The device works as follows, ₅₅

Так как схема симметрична, то рассмотрим ее работу в один полупериод для одной из фаз.Since the circuit is symmetrical, we consider its operation in one half-cycle for one of the phases.

Б начале каждого полупериода вторичного тока происходит подзаряд через выпрямитель 3 соответствующего накопительного конденсатора 4. При этом симистор 8 закрыт. Как только напряжение на конденсаторе 4 превысит уровень напряжения стабилизации задающего стабилитрона 10, через маломощный выпрямитель 9 управления начинает протекать ток управляющего электрода симистора 8, который, включаясь, закорачивает вторичную обмотку трансформатора тока на измерительный резистор 2. При изменении полярности вторичного тока симистор 8 выключается и вышеописанный процесс повторяется для другого накопительного конденсатора 4, заряженного до напряжения противоположной полярности.At the beginning of each half-cycle of the secondary current, recharging occurs through the rectifier 3 of the corresponding storage capacitor 4. In this case, the triac 8 is closed. As soon as the voltage across the capacitor 4 exceeds the stabilization voltage level of the master zener diode 10, the current of the control electrode of the triac 8 starts to flow through the low-power rectifier 9, which, turning on, shortens the secondary winding of the current transformer to the measuring resistor 2. When the polarity of the secondary current changes, the triac 8 turns off and the above process is repeated for another storage capacitor 4 charged to a voltage of opposite polarity.

Ток протекает по измерительному резистору 2 независимо от коммутационного состояния симистора 8. Напряжение на измерительном резисторе 2, пропорциональное величине первичного тока фазы, поступает на вход органа 7 контроля тока, который в аварийной ситуации (перегрузка, междуфаэное или однофазное короткое замыкание, обрыв фазы) подает по заданной программе команду на включение тиристора 5, в результате чего оба конденсатора 4, включенные последовательно , разряжаются на катушку 6 электромеханического исполнительного органа.The current flows through the measuring resistor 2, regardless of the switching state of the triac 8. The voltage on the measuring resistor 2, proportional to the magnitude of the primary current of the phase, is supplied to the input of the current control 7, which in an emergency situation (overload, inter-phase or single-phase short circuit, open circuit) according to a given program, the command to turn on the thyristor 5, as a result of which both capacitors 4 connected in series are discharged to the coil 6 of the electromechanical actuator.

Контроль напряжения на каждом из двух накопительных конденсаторов 4 осуществляется с помощью одного стабилитрона 10.The voltage control on each of the two storage capacitors 4 is carried out using one zener diode 10.

В однофазном и трехфазных режимах контроль напряжений на конденсаторах в каждом полупериоде первичного тока выполняется раздельно.In single-phase and three-phase modes, the voltage control on the capacitors in each half-cycle of the primary current is performed separately.

В положительный полупериод задающий стабилитрон 10 подключается к накопительному конденсатору 4 и катодной группе с маломощного выпрямителя 9 управления через открытый диод 1 2 и открытый транзистор 13 ключа. Насыщенное состояние транзистора 13 обеспечивает транзистор 14 управления отпираеьым током, протекающим через резистор 16, при этом диод 11 закрыт.In the positive half-cycle, the master zener diode 10 is connected to the storage capacitor 4 and the cathode group from a low-power control rectifier 9 through an open diode 1 2 and an open key transistor 13. The saturated state of the transistor 13 provides the transistor 14 controls the unlocked current flowing through the resistor 16, while the diode 11 is closed.

В отрицателыплй полупериод первичного тока задающий стабилитрон 10 контролирует уровень напряжения на другом накопительном конденсаторе 4, подключаясь к общей точке схемы через открытый диод 11, при этом диод 12 закрыт. Транзистор 13 ключа тоже закрыт, поскольку закрывается транзистор 14 узла управления током смещения, протекающим через открытый диод 18 и резистор 17 смещения.In a negative half-cycle of the primary current, the master zener diode 10 controls the voltage level at another storage capacitor 4, connecting to a common point in the circuit through an open diode 11, while the diode 12 is closed. The key transistor 13 is also closed, since the transistor 14 of the bias current control unit flowing through the open diode 18 and the bias resistor 17 is closed.

Сопротивления резисторов 15 и 16 равны между собой и в два раза превышают сопротивление резистора 17. Такое соотношение должно выполняться для .обеспечения правильного функционирования схемы в дуахфазном режиме работы. В этом режиме работы (из-за сдвига фаз на 180°), подзаряд обоих конденсаторов 4 происходит одновременно. Для контроля напряжения на конденсаторах 4 в этом.режиме введен транзисторный ключ, настроенный на приоритетный контроль напряжения на конденсаторе, заряжаемом отрицательной полуволной тока. Поскольку коэффициент пульсаций напряжения на конденсаторах 4 достаточно мал, то принятое соотношение сопротивлений резисторов 16 и 17 обеспечивает такой приоритет за счет запирания транзистора 14 узла управления, что приводит к запиранию транзистора 13 ключа.The resistances of the resistors 15 and 16 are equal to each other and are twice as high as the resistance of the resistor 17. This ratio must be fulfilled in order to ensure the correct functioning of the circuit in two-phase operation. In this mode of operation (due to a phase shift of 180 °), the charging of both capacitors 4 occurs simultaneously. To control the voltage across the capacitors 4, a transistor switch is inserted in this mode, which is configured to priority control the voltage across the capacitor charged by the negative half-wave current. Since the coefficient of voltage ripple on the capacitors 4 is quite small, the adopted ratio of the resistances of the resistors 16 and 17 provides such a priority by locking the transistor 14 of the control unit, which leads to the locking of the transistor 13 of the key.

Как только включается симистор 8 фазы, где ток имеет отрицательную полярность, транзистор 14 открывается, вызывая отпирание транзистора 13· ключа, и задающий стабилитрон 10 переключается на контроль напряжения на втором конденсаторе (подзаряжаемом положительной полуволной тока), Поскольку в двухфазном режиме токи в фазах одинаковы, а нагрузки в оба полуперирда симметричны, то оба симистора 8 включаются практически одновременно.As soon as the triac 8 phase, where the current has a negative polarity, turns on, the transistor 14 opens, causing the transistor 13 · key to unlock, and the master zener diode 10 switches to voltage control on the second capacitor (rechargeable positive half-wave current), since in the two-phase mode the currents in phases are the same , and the loads in both half-waves are symmetrical, then both triacs 8 are turned on almost simultaneously.

В предлагаемом устройстве (по сравнению с прототипом) обеспечивается симметричный режим работы трансформаторов тока за счет использования единственного контролирующего стабилитрона, тогда как в известном устройстве не удается достичь,полной симметрии в работе трансформаторов тока вследствие использования двух контролирующих стабилитронов, неизбежно имеющих технологический разброс по уровням напряжения стабилизации. Таким образом, предлагаемое устройство обеспечивает снижение величины токовой погрешности трансформаторов тока в рабочей зоне первичных токов и повышает надежность защиты.The proposed device (in comparison with the prototype) provides a symmetrical mode of operation of current transformers through the use of a single control zener diode, while in the known device it is not possible to achieve complete symmetry in the operation of current transformers due to the use of two control zener diodes, which inevitably have a technological spread in voltage levels stabilization. Thus, the proposed device provides a reduction in the current error of current transformers in the working area of primary currents and increases the reliability of protection.

Claims

The invention relates to devices for protection against overloads, interphase and single-phase short circuits, phase failure, in particular, to blocks of semiconductor maximum releases of low-voltage circuit breakers. The purpose of the invention is to increase the reliability of the device. The drawing shows a diagram of the proposed device. The device contains current transformers 1, included in each phase of the protected network. The beginnings of the secondary winding of current transformers 1 through measuring resistors 2 are connected to the star, and the cables through power rectifier 3 are connected to storage capacitors 4. Parallel to the output of rectifier 3, a thyristor 5 is connected - coil 6 of an electromechanical actuator. The power supply of positive and negative polarity is removed from each storage capacitor 4 relative to a common point for current control organ 7. The triacs 8 are connected by cathodes to the input terminals of the power rectifier 3, control electrodes to the input terminals of the low-power control rectifier 9, the anodes to the common point of the measuring resistors 2 and the storage capacitors 4 to the common point of the circuit. To the input terminals of a low-power rectifier 9, a master zener diode 10 is connected, shunted by a chain of two in series and according to V1 coupled diodes 11 and 12, through a transis. torus 13 key. The transistor 14 controlling the transistor 13 of the key, connecting the collector through the resistor 15 to the base of the transistor 13 of the key, the base through the resistor 16 to the connection point of the cathode group of the control rectifier 9 and emitter of the transistor 13 key, through the resistor 17 to the connection point of the anode The rectifier groups are 9 control and diode 12. Diode 18 is connected in a counter-parapel basis to the emitter junction of control transistor 14. Resistor 19 shunts the base - emitter junction of the transistor 13. The device works as follows. Since the circuit is symmetric, we consider its operation in one half-period for one of the phases. At the beginning of each half-cycle of the secondary current, recharge occurs through the rectifier 3 of the corresponding storage capacitor 4, and the triac 8 is closed. As soon as the voltage on the capacitor 4 exceeds the stabilization voltage level of the master zener diode 10, the control electrode current of the triac 8 starts to flow through the low-power control rectifier 9, which short-circuits the secondary winding of the current transformer to the measuring resistor

2. When the polarity of the secondary current is changed, the triac 8 is turned off and the above described process is repeated for another storage capacitor 4 charged to a voltage of opposite polarity. The current flows through the measuring resistor 2 regardless of the switching state of the triac 8, the voltage across the measuring resistor 2, which is proportional to the primary phase current, enters the input of the current control body 7, which in an emergency (overload, phase-to-phase or single-phase short circuit, phase failure ) gives the command to turn on the thyristor 5 according to a given program, as a result of which both capacitors 4, connected in series, are discharged to the coil 6 of the electromechanical actuator. Voltage monitoring on each of the two storage capacitors 4 is carried out using one Zener diode 10. In single-phase and three-phase modes, the monitoring of voltages on the capacitors in each half-cycle of the primary current is performed separately. In the positive half-period of the dead clockwise Zener diode 10 is connected to the storage capacitor 4 and the cathode group with a low-power control rectifier 9 through the open diode 1 2 and the open transistor 13 of the key. The steady state of the transistor 13 provides the transistor 14 for controlling the unlocking current flowing through the resistor 16, and the diode I is closed, In the negative half-cycle of the primary current, the master zener diode 0 controls the voltage level at the other storage capacitor 4, connected to the common point of the circuit through the open diode 11, while the diode 12 is closed. The transistor 13 of the switch is also closed because the transistor 14 of the bias current control node flowing through the open diode 18 and the bias resistor 17 is closed. The resistances of resistors 15 and 16 are equal to each other and are twice as high as the resistance of resistor 17. This relationship must be met in order to ensure proper functioning of the circuit in duach phase operation. In this work rekit (due to a phase shift of 180), the charging of both capacitors 4 takes place simultaneously. To control the voltage on the capacitors 4, a transistor switch was inserted in this mode, which is configured to take priority control of the voltage on the capacitor charged by negative half-wave current. Since the voltage ripple factor on the capacitors 4 is quite small, the adopted ratio of the resistances of the resistors 16 and 17 provides such a priority by locking the transistor 14 of the control unit, which causes the key transistor 13 to be locked. As soon as the triac 8 of the phase is turned on, where the current has a negative polarity, the transistor 14 opens, causing the key transistor 13 to be unlocked, and the zener diode 10 switches to voltage control on the second capacitor (rechargeable positive half-wave current), since the currents in the two-phase mode the phases are the same, and the loads in both half-perirs are symmetric, then both of the 8 sides are switched on almost simultaneously. In the proposed device (as compared to the prototype), the current transformers are symmetrically operated by using a single controlling Zener diode, while in the known device it is not possible to achieve full symmetry in the operation of current transformers due to the use of two Controlled Zener diodes, inevitably spread over technological levels voltage stabilization. Thus, the proposed device provides a reduction in the magnitude of the current error of the current transformers in the working zone of the primary currents and improves the reliability of the protection. The invention The device dp current protection against damage in an AC network, containing current transformers by the number of phases of the network, to the beginning of the secondary windings of which the first terminals of measuring resistors are connected, the second terminals of measuring resistors are interconnected and connected to the input of the current control body, the KOToJioro output is connected to the control electrode of the thyristor, whose cathode is directly, and the anode through the coil of the electromechanical actuator is connected respectively to the first and second the outputs of the power rectifier, each of these outputs are also connected to the first inputs of the first and second storage capacitors respectively, the second inputs of which are connected to each other and to the common point of the measuring resistors, the inputs of the power rectifier are connected to the ends of the secondary windings of current transformers, the triacs by the number the network phases, the cathodes of which are connected to the corresponding inputs of the power rectifier, and the anodes to the common point of the measuring resistors, the control rectifier, the inputs of which are connected to the corresponding Triac control triacs of the triacs, setting the zener diode, characterized in that, in order to increase the reliability of the device in operation, three diodes are additionally introduced, a transistor switch, a control transistor and three resistors, while the setting zener diode is connected to the first by its anode .the output of the rectifier control, the cathode to the second output of the specified rectifier through a junction collector emitter of a transistor switch, the first and second diodes are connected in series with each other and connected in parallel to the driver Zener diode, the connection point of the first and second diodes is connected to the anode of the third diode, the cathode of which is connected to the connection point of the first leads of the second and third resistors, as well as the base of the control transistor, the collector of the control transistor 5 12675226

pa through the first resistor and again outside the control rectifier, the base of the shunt resistor and the second wrench - to the connection point of the second resistor are connected to the first and resistor shunt output of the controller rectifier, while the resistance of the first and

No, the emitter of the control transistor-j of the second resistors is equal in size to the common measuring point, and the resistance of the third resistor resistors, the second connector is equal to half the resistance of the third resistor to the first at the output of the first resistor.