SU1441473A1 - Switching device - Google Patents

Abstract

The invention can be used for contactless switching of a three-phase load. The purpose of the invention is to increase the reliability of work by reducing the number of contact elements. The three-phase bridge rectifier contains diodes 2-6 and a thyristor / T / 7. T 8 is bounded by a resistor 9. In addition, the switch turns on diodes 11 and 15. T 8 is disconnected (load 1 is disconnected) when the voltage of one, two and three phases. Moreover, after the restoration of the supply voltage, the automatic switching on of the load 1 does not occur, since capacitor 10 discharge. 1 il.

Description

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The invention relates to a pulse technique and can be used for contactless switching of a three-phase load.

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

The drawing shows a circuit diagram of the switch.

The switchboard contains a three-phase load 1, connected between phases A, B and C of the AC network and the input of a three-phase bridge rectifier, J5 l, containing diodes 2-6 and the first thyristor 7, included in one of the anode arm. The second thyristor is turned on at the output of the bridge mittel

8, referenced by the first resistor 20

9, the capacitor 10 is connected by the first plate to the cathode of the thyristor 7 through the first diode 11 and the second resistor 12 connected in series, and the second plate through the third 13 and fourth and 14 resistors to the cathode and the control electrode of the thyristor 8, respectively. The chain of series-connected second diode 15

and the fifth resistor 16 is connected to the thyristor 7 control electrode by a cathode terminal, and to the thyristor 7 anode through the closing contacts 17 of the start switch and to the anode of the third diode 18, the cathode of which is connected to the first capacitor plate 10 ,

The switch works as follows) |

When the contacts 17 are open, the type 7 resistors 7 and 8 are locked, and the capacitor 10 is charged to the peak value of the line voltage. The capacitor 10 is charged along the circuit: phase C (phase B) - load 1 - di-DZ od.2 (diode 4) - resistor 9 - resistor 13 - diode 11 - resistor 12 - load 1 - phase A, the current through load 1 is determined by the resistance of resistor 9, and the voltage -Q in it is almost zero, which corresponds to the switched off state of the switch.

To excite the load 1, it is necessary to close the contacts 17, At. Thus, the control electrode of the thyristor 7 through the resistor 16 and the diode 15 is connected to the anode of the thyristor 7, as a result of which the discharge circuit of the capacitor 10 is closed through the resistor 14 connected in series and the transition of the control electrode - cathode of the thyristor 8 (the discharge of the capacitor 10 through the third resistor 13), Pazp dnvv the current of the capacitor 10 unlocks the thyristor 8, which causes the flow of control current of the thyristor 7 through the circuit: phase C (phase b) - load 1 - diode 2 (diode 4), thyristor 8 - contacts 17 - diode 15 - resistor 16 - control ne the thyristor 7 - load 1 - phase A, the thyristor 7 is unlocked, and the thyristor 8 remains in a conducting state due to the flow of continuous rectified current through it. The load 1 is under the network voltage.

The disconnection of the load 1 is accomplished by opening the contacts 17. This breaks the power supply circuit of the control transition of the thyristor 7, as a result of which it closes, which causes the thyristor 8 to turn off.

The thyristor 8 is turned off (load 1 is disconnected) even if one, two and three phases disappear, and after the supply voltage is restored, despite the fact that contacts 17 are closed, automatic switching on of load 1 does not occur under network voltage. as the capacitor 10 is discharged, dp re-enable the switch it is necessary to open and re-close the contacts 17,

Claims (1)

Invention Formula A switch containing a three-phase load, connected between the phases of an AC network and the input of a three-phase bridge terminal, into one The first thyristor, the second thyristor, which is connected at the output of the Three-phase bridge rectifier and shunted by the first resistor, the capacitor connected by the first lining to the cathode of the first thyristor through the second resistor connected in series and the first diode connected in accordance with the first thyristor along the relation to the mains supply, and the second plate through the third and fourth resistors - to the cathode and control electrode of the second 31441473 of the thyristor, respectively, chained by the fact that, with ku from successively connected to a target. reliability of operation, the second diode and the fifth resistor, the third diode is inserted into it, the anode co-connected by the anode output is connected through the anode output the closing contacts of the starting switch from the series-connected to the anode of the first thyristor, and the second diode and the fifth resis- tic-cathode lead to the control pa, and the cathode is connected to the first around-electrode of the first thyristor, and the capacitor capacitance.