SU1410178A1 - Apparatus for protecting three-phase user from phase failure - Google Patents

Abstract

The invention relates to electrical engineering, namely to control and protection systems for three-phase consumers. The purpose of the invention is to increase reliability by reducing the contact elements of the device. Contains magnetic starter 3, thyristor 5, capacitor 8, diodes 6, 19, 13, 14, three-phase half-wave rectifiers 11, 16, button "Stop 10, button" Start 12 and resistors 7, 15. With a brief disappearance of voltage in one from the phases, the thyristor 5 is closed. After a time, the thyristor is turned on and the magnetic starter 3 is again under voltage. If the time of the disappearance of the voltage in the phase exceeds the time at which the charge current of the capacitor 8 becomes less than the turn-on current of the thyristor 5, the thyristor will not be able to turn on and the magnetic starter 3 will be de-energized, contacts 2 open, de-energized consumer 1. 7 Il. S

Description

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The invention relates to electrical engineering, namely to control and protection systems for three-phase consumers.

The aim of the invention is to increase reliability by reducing the number of contact elements.

FIG. 1 shows the basic electrical circuit of the device proposed; in fig. 2 is a timing diagram of the voltages to the power signal during normal operation of the consumer; in fig. 3 is a time diagram of the current, the path w, it through the thyristor during normal operation of the consumer; in fig. 4 is a timing diagram of the voltage on the power rails during a short-term short circuit in phase C; in fig. 5 - time diagram of the current passing through the thyristor during a short-term short circuit in phase C (three-phase consumer is on); in fig. 6 is a timing diagram of the voltage on the power rails in the event of a long circuit or an open phase C; in fig. 7 is a time diagram of the current passing through the thyristor during a long circuit or an open phase C.

The device for protection of a three-phase consumer from a phase failure consists of a three-phase consumer 1 connected by means of power contacts 2 of the reacting organ (magnetic actuator) 3 to an input power supply 4, a thyristor 5, whose control electrode is through a chain consisting of series-connected second diode b, resistor 7, capacitor 8, first diode 9, is connected to the anode of the thyristor 5, the cathode of which is connected through series-connected disconnecting contact 10 of the Stop button and coil 3 of the magnetic actuator to hog wire. The output of the first half-wave three-phase rectifier 11 through the closing contact 12 of the Start button is connected to the thyristor cathode 5, and through diode 13 to the connection point of diode 9 and capacitor 8. The connection point of the capacitor 8 to the resistor 7 is through the third connected diode 14 and resistor 15 The current used to limit the discharge current of the capacitor 8 is connected to the cathode of the thyristor 5. The output of the second half-wave three-phase rectifier 16 is connected to the anode of the thyristor 5. The coil 3 of the magnetic starter is shunted by a diode 17.

The device for protection of a three-phase rectifier against phase failure works as follows.

When the input automat 4 is turned on and the start button, the voltage removed from the rectifier AND, is pressed through the contact 10 of the button, the stop is applied to the winding 3 of the magnetic starter. The reactive organ 3 is switched on by commuting its contacts to the three-phase supply circuit

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Consumer 1. When the contacts 12 of the Start button 12 are opened, the elements 9, 8, 7, 6 turn on the thyristor 5, ensuring the blocking of the magnetic starter 3 (Fig. 2 and 3). In case of short-term voltage disappearance in one of the phases caused by a short circuit in the adjacent network sections, for example, a short circuit of the consumer 19 connected through the fuse 18, the rectified voltage decreases to zero in the interval of 60 el. The hail Thyristor 5 is closed at this time (Fig. 4, 5). After a certain time has elapsed, the thyristor 5, due to the charging current of the capacitor 8, is turned on again and the reaction body 3 is again under voltage. If the time of the disappearance of the voltage in the phase exceeds the time at which the charge current of the capacitor 8 becomes less than the turn-on current of the thyristor 5, the thyristor can also be turned on by the reacting body 3 and its contacts are open, de-energizing consumer 1 (Fig. 6, 7).

Switching off the three-phase consumer is carried out in the usual way - by pressing the "Stop. When the three-phase consumer is switched on again, the diode 13 - contact 12 of the “Start-up - resistor 15 - diode 14” button of the capacitor 8 is discharged.

The time of the circuit insensitivity to short-circuits of one of the phases is determined by the capacitance of the capacitor 8 and the resistance of its circuit.

The high technical reliability of the proposed device is its advantage and advantage over its analogues. In addition, reducing the number of connecting conductors on the control buttons with remote control reduces wire consumption.

Claims (1)

Invention Formula A device for protection of a three-phase consumer against phase failure, containing the first three-phase half-wave rectifier, equipped with leads for connecting the magnetic starter on the consumer side to the power contacts, the output of the rectifier is connected to the thyristor anode, the first diode, the anode of which is connected to the output of the first rectifier, and the cathode through the capacitor to the first terminal of the first resistor, the second three-phase half-wave rectifier, equipped with leads for connection to the power contacts of the magnetic starter The power supply, the output of which is connected to the first output of the closing contact of the Start button, the Stop button with the disconnecting contact, the first output of which is connected to the cathode, 6m of the thyristor, and the second to the first output of the magnetic starter winding, the second output of which It is designed to be connected to the neutral wire of the network, characterized in that, in order to increase reliability by reducing the number of contact elements, a second resistor, a second, third, and fourth diode are additionally introduced into it, the second diode being connected to the cathode ene to the control electrode of the thyristor and an anode - a second terminal the first resistor, the first output of which is connected to the cathode of the third diode, the anode of which through the second resistor is connected to the second output of the closing contact of the Start button and the first output of the disconnecting contact of the Stop button, the fourth diode is connected by the anode to the cathode of the first diode, and the cathode to the three-phase output half-wave second rectifier. / I in C x YYYYYYYYY. And S with LAAAAAAAAA / cpi / e.Z f srig.Z t A b / YYYYYV H / KLLHH FI.4 VA / srig.6 and KIT / Y / Y g, 1ЛКЛ / Л / Л / e o 7