SU1501210A1 - Arrangement for protecting three-phase consumers from supply asymmetry - Google Patents

Abstract

The invention relates to electrical engineering and is intended for use in relay protection systems and automatic power supplies for three-phase consumers. The purpose of the invention is to increase the reliability of protection by preventing the power supply to the consumer when the supply network is asymmetrical, ensuring stability against short-term deviations of the power supply mode and adjusting the protection operation setpoint over a wide range. In the normal mode of the mains supply, at the output of the three-phase half-wave rectifier 1 connected to the network by terminals 2, 3, 4, a constant voltage is generated, and in the star's neutral, formed by the ballast elements 13, 14, 15, the voltage is zero. When the start button 6 is pressed, the actuator 7 is switched on, which becomes self-locking via the auxiliary contact 8 and is held in the actuated state after releasing the start button 6. Thyristor 11 is locked. The Executive body 7 power contacts 22 connects consumers to the mains. The consumers are disconnected by pressing the "Stop" button 5, while the executive body 7 de-energizes and opens the power contacts 22. With the asymmetry of the supply voltage in the star neutral formed by the elements 13, 14, 15, the bias voltage of the neutral is formed, which through the diode 10 charges the capacitor 16. When the set voltage on the capacitor 16 is reached, the thyristor 11 is triggered, shunting the control winding of the actuator 7, which is turned off, the blocking contact 8 and the power contacts 22 open. aets from the mains. In case of pressing the "Start" button 6 with unacceptable mains supply asymmetry, the executive body 7 remains in the off state, since its winding is shunted with an open thyristor 11. 1 Il.

Description

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There is a pressing of the button 5 Stop, while the executive body 7 de-energizes and softens; the power contacts 22. With the asymmetry of the supply voltage in the neutral of the star, formed by elements 13, 14, 15, the bias voltage of the neutral is formed, which through diode 10 It charges the capacitor 16. When the required voltage is reached at the capacitor 16, the thyristor 11 is activated,

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shunt control winding of the actuator 7, which is turned off, the interlocking contact 8 and the power contacts 22 open. The consumer is disconnected from the mains. In case of pressing the Start button 6 with unacceptable mains supply asymmetry, the executive unit 7 remains in the off state, since its winding is shunted by an open thyristor 11. 1 Il.

The invention relates to electrical engineering and is intended for use in relay protection and automation systems for power supply to three-phase consumers.

The purpose of the invention is to increase the reliability of protection by preventing the power supply to the consumer when the supply network is asymmetrical, ensuring stability against short-term power outages and adjusting the protection operation setpoint over a wide range.

The drawing shows a diagram of the device.

The device for protection of three-phase consumers from asymmetrical power supply modes contains a three-phase half-wave rectifier 1 with output pins 2, 3, 4 for connecting to the supply mains phases, a 5 Stop button with a damper and a Start button 6 with closing contacts, an actuator 7 with a closing unit -contact 8, two diodes 9, 10, thyristor 11, first resistor 12, three ballasts 13, 14, 15, two capacitors 16, 17 and pin 18 for connection to the zero point of the supply network. The first pin of the D contact of the button 5 Stop is connected to the first pins of the closing contact of the 6 Start button and the closing block 8 of the actuator 7, the control winding of which is shunted by the first diode 9. The control electrode of the thyristor 11 is connected to the first output of the first resistor 12, the ballast elements 13, 14, 15 are connected to the first terminals with terminals 2, 3, A for connecting to the mains phases and the second terminals to the first terminal of the second diode 10, the second terminal

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through which the first capacitor 16 is connected to the terminal 18 for connection to the zero point of the supply network. The second capacitor 17 is connected to the first output of the thyristor 11. The device has three resistors 19, 20, 21. The first output of the first diode 9, the second output of the thyristor 11, the second output of the second capacitor 17 and the first outputs of the third 20 and fourth 21 resistors are connected to pin 18 to connect to the zero point of the mains. The second output of the opening contact of the button 5 Stop through the second resistor 19 is connected to the output of the three-phase half-wave rectifier 1, and the second output of the closing contact of the button 6 Start is connected to the second output of the closing contact 8 of the actuator 7, to the second output of the first diode 9 and to the first thyristor terminal 11. The second terminal of the first resistor 12 is connected to the second terminal of the second diode 10, the first terminal of which is connected to the second terminal of the third resistor 20. The control electrode of the thyristor 11 is connected to the second terminal of the fourth the resistor 21, the first diode is connected in opposite direction, and the thyristor 11 according to the polarity of the three-phase half-wave rectifier 1.

The actuator 7 can be made in the form of a magnetic starter with power contacts 22 included in the supply lines of the consumer phases, and the ballast elements 13, 14, 15 in the form of capacitors or resistors.

The device works as follows.

In the normal mode of the mains supply, the output voltage of the rectifier 1 is formed by a constant voltage determined by the voltage of the network, while in the star's neutral, formed by balo, elliptical elements 13, 1А, 15, the voltage is zero. When the Start button 6 is pressed, the actuator 7 is turned on, which becomes self-blocking via the auxiliary contact 8 and is kept in the actuated state after releasing the Start button 6 The thyristor 11 is locked. The executive body 7 with its power contacts 22 connects consumers to the mains. The consumers are disconnected by pressing the 5 button. At the same time, the executive unit 7 de-energizes and opens the power contacts 22.

With the asymmetry of the supply voltage in the star's neutral, formed by the ballast elements 13, 14 and 15, the neutral bias voltage is generated, which is rectified by the diode 10. The capacitor 16 is charged. When the set voltage on the capacitor 16 is reached, the thyristor 11 triggers a shunt control the winding is (input) of the actuator 7, which is turned off, the blocking contact opening 8 and the power contacts in the consumer power supply circuit. The latter is disconnected from the mains.

In case of pressing the Start button 6 with unacceptable mains supply asymmetry, the executive unit 7 remains in the off state, since its winding is shunted by the thyristor 11, i.e. When using the device, the possibility of forcibly holding the consumer in the incomplete phase power mode is prevented by pressing the Start button. The stability of the protection against short-term deviations from the normal power supply mode is ensured by selecting the constant time of the charge circuit of the capacitor 16.

Claims (1)

Adjustment of the setpoint of operation (sensitivity) of the protection is carried out by a resistor 20, in this case protection can be provided in the asymmetry range from 5% to break of one or two phases of the network Device to protect three-phase consumers from asymmetrical 0 five 0 five 0 five 0 five Pittny modes, containing a three-phase half-wave rectifier with input terminals for connection) 1 and to the supply mains phases, the Stop button C disconnecting and the Start button with closing contacts, the actuator with the closing block contact, two diodes, a thyristor, the first resistor, three a ballast element, two capacitors and a terminal for connection to the zero point of the supply network, the first output of the opening contact of the Stop button is connected to the first terminals of the closing contact of the Start button and the closing contact block About the organ, the control winding of which is shunted by the first diode, the control electrode of the thyristor is connected to the first end of the first resistor, the ballast elements are connected to the power supply phases and the second leads to the first output of the second diode, the second output of which The first capacitor is connected to an output for connecting to the zero point of the supply network, and the second capacitor is connected to the first output of the first capacitor of the thyristor, characterized in that, in order to increase the reliability of protection By preventing the power supply to the consumer when the supply network is asymmetrical, providing resistance to short-term deviations of the power supply mode and adjusting the protection setting setpoint in a wide range, three resistors are inserted in the device, the first output of the first diode, the second output of the thyristor, the second output of the second capacitor and the first outputs the third and fourth resistors are connected to the pin for connecting to the zero point of the mains; the second output of the opening contact of the Stop button is connected via the second resistor with the output of a three-phase half-wave rectifier, and the second output of the closing contact of the Start button - with the second output of the closing block contact of the actuator, with the intrusion output of the first diode and with the first output of the thyristor, the second output of the first resistor is connected to the transient-output of the second diode, the first output which is connected to the second output of the third 715012108 a control resistor, the control electrode is connected in opposite direction, and the thyristor of the thyristor is connected to the second output terminal according to the polarity of the three-phase one of the fourth resistor, the first half-period rectifier.