RU1798851C - Gear for protection of three-phase load against change of alternation and open phase - Google Patents

Abstract

Usage: relay protection of the load against incorrect phase rotation and out of phase operation. SUMMARY OF THE INVENTION: the device comprises a three-phase, half-wave rectifier with thyristors connected by anodes to phases A, B. C, while the control electrodes of the thyristors are connected respectively to the previous phases C, A and B, to phases A, B , With the thyristor anodes connected, the second rectifier, the thyristor control electrodes are connected to the subsequent phases B, C, A. If the phases of the power supply are not correctly alternated, the first thyristors will be locked and the second thyristors will be open even when the On button is pressed. the second magnetic starter will operate and, with its power contacts, feeds the correct phase rotation to the load. 1 ill.

Description

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The invention relates to electrical engineering, in particular to relay protection, and is intended to automatically supply to the load the correct phase rotation during arbitrary phase rotation of the supply network and protection against under-phase conditions.

The purpose of the invention is to increase the reliability of the power supply of the load and reduce the power consumption of the device by switching the load with only one switching element with an arbitrary alternation of phases of the supply network.

The drawing shows a diagram of a device for protecting a three-phase load from changing phase rotation and phase failure.

The device contains a three-phase one-half-wave rectifier with thyristors 1 - 3. connected anodes respectively to phases A, B and C.

thyristor control electrodes are connected respectively to the previous phases C, A and B through resistors 4-6. Between the output of the rectifier and the neutral wire, the NC contacts 7 of the Off button are sequentially connected, the thyristor 8, the control electrode of which is through the resistor 9 and the NC contacts 10 of the On button. connected to the anode, the winding of the magnetic starter 11, shunted by the auxiliary diode 12, and the opening contacts 13 of the second magnetic starter. Parallel to the first one, a second half-wave rectifier with thyristors 14-16 connected by anodes to the A.V.C phases, respectively, is connected to the phases of the network, and the control electrodes through resistors 17-19, respectively, to the subsequent phases B, C. A. Between the output of the rectifier and the neutral wire in series

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included are the second NC contacts 20 of the 0Tl button :, thyristor 21, the control electrode of which is through the resistor 22 and the second NC contacts 23 of the On button. connected to the anode, the winding of the second magnetic starter 24, shunted by the auxiliary diode 25, and the disconnect contacts 26 of the first magnetic starter. Through power contacts 27 of the first or power contacts 28 of the second magnetic starter, a direct or reverse phase sequence of the supply network is applied to the load, respectively.

The device operates as follows. .-. . . : ...-. : -: .....

With the correct alternation of the phases of the supply network, thyristors 1-3 of the first body will be opened, since the voltages of the previous phases, which are 120 ° ahead of the voltage on the anodes, are applied to their control electrodes through resistors 4-6. The thyristors 14-16 of the second rectifier will be closed, since the voltages of the subsequent phases, which are 120 ° behind the voltage on the anodes, are applied to their control electrodes through resistors 17-19. Thus, with the correct alternation of the phases of the supply network, a constant voltage will be present only at the output of the first rectifier, and pressing the On button. will lead to the opening of only the thyristor 21 and the current flowing around the winding 24. The second magnetic starter will trip, close its power contacts 26, swap phases A and B and apply the correct phase rotation to the load.

Resistors 4.5. 6,9,17,18,19,22 restrict the flow of control through the corresponding thyristor. The opening contacts 13 and 26 prevent the simultaneous operation of both starters and the occurrence of a short circuit on the load side. Auxiliary diodes 12 and 25 prevent overvoltage on the windings 11 and 24, respectively.

In the case of an out-of-phase mode, the output voltages of the first and second rectifiers appear current-free pauses due to the absence of voltage of one of the phases. When the On button is depressed (pins 10 and 23 are open), if such a voltage at the anode of the turned on thyristor 8 or 21 leads to its closure in the first pause and to deenergize the corresponding winding of the magnetic starter.

Similarly, the load is switched off when the button is pressed.

Off: when contacts 7 and 20 are opened, the voltage at the anode of thyristor 8 or 21 disappears, the thyristor, which was previously in this open state, is locked,

the corresponding magnetic starter is disconnected, the load is de-energized. Thus, the proposed device provides automatic feeding to the load of the correct phase rotation regardless of the phase rotation of the supply network and disconnects the load from the network in non-phase mode, and all switching is carried out by only one magnetic starter, which allows to increase

reliability of the power supply (since the supply network gets to the load through only one group of contacts) and halve the consumption of electric power from the network with the correct phase rotation (since current

Claims (1)

the winding of only one magnetic starter flows around.) Claims A device for protecting a three-phase load from changing phase rotation and phase failure, containing two three-phase single-half-wave rectifiers, an Off button, an On button, two switching thyristors, two magnetic starters, and the output of the first rectifier through the Off button. and the first switching thyristor is connected to the first terminal of the coil of the first magnetic starter, inactivated by the first diode, a control electrode the first switching thyristor is connected through a resistor and the contacts of the On button. with the anode of the said thyristor, the cathode of the second switching thyristor is connected to the first output of the coil of the second a magnetic starter mounted with a second diode, characterized in that, in order to increase the reliability of the power supply to the load and reduce the power consumption of the device by load switching with only one switching element during arbitrary alternation of phases of the supply network, thyristors are installed in the arms of the rectifiers, the anodes of which are connected to the terminals for connecting to the phase wires of the first, second and third phases of the network, while the control electrodes of each thyristor are in the first rectifier through the limiting resistors connected to the terminals for connection to the phase conductor of the previous phase, and in the second to the terminals for connection to the phase conductor of the subsequent phase of the supply network, while the output of the second rectified through the second contacts Off buttons connected to the anode of the second switching thyristor. the control electrode of which, via an additional resistor and second contacts of the On button. connected to its anode, the second terminal of the coil of the first magnetic starter through the opening block contact of the second magnetic starter, and the second terminal of the coil of the second magnetic starter through the block contact Stretch load The first magnetic starter is connected to the terminal for connection to the neutral conductor of the mains supply, while the power contacts of the first and second magnetic starters are reversely connected by their terminals and connected between the terminals to connect to the phase conductors of the mains and the load.