SU1499472A1 - D.c. gate - Google Patents

Abstract

The invention is intended for the protective shutdown of consumers in coal mines. The purpose of the invention is to increase the speed and reliability of operation. The dc key contains thyristors 1, 5, capacitors 6, 7, chokes 9, 10, diodes 11, 12, 13, the first circuit 14 of charging. The introduction of the third thyristor 8 and its connection to the capacitor 7 through the choke 10, the introduction of the second circuit 17, charging the capacitor 7 and connecting the cathodes of diodes 12 and 13 to the anode and the cathode of the thyristor 1, respectively, shortens the recharging time of the capacitors 6, 7 and eliminates overvoltage on load 2. 1 Il.

Description

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31499472

The invention relates to a pulsed technique and can be used in schemes for the protective disconnection of consumers in the conditions of coal mines.

The purpose of the invention is to increase a / c effect by reducing the recharging time of capacitors and improving operating reliability by eliminating overvoltages on load.

The drawing shows the principal key diagram.

The dc switch contains the first thyristor 1., switched on sequentially with load 2 between poles 3 and 4 of the power supply, second thyristor 5, first capacitor 6 connected between the cathodes of thyristors 1 and 5, second capacitor 7, between the 20 anode of the thyristor 5 and the anode of the third thyristor 8, the first choke 9 connected between the anodes of the thyristors 1 and 8, the second choke 10 connected to the anode of the thyristor 5 and the cathode 25 of the thyristor 8, the first diode 11, shunt the load 2 in the reverse direction, the second diode 12, connected by a cathode to the thyristor node 1, and the anode with the cathodes of thyristor 1 and the third diode 13, 30 of which the anode is connected to the cathode of the thyristor 5, the first charge circuit 14 of the diode 15 connected in series and the third droplet 16 connected between the thyristor cathode 5.35 and pole 4 , and the second subtitle circuit 17, connected between the anode of the thyristor 5 and pole 4.

The key works as follows. In the initial state, the thyristors 1.540 and 8 are closed, the capacitor 6 is discharged, and the capacitor 7 is charged up to the voltage between poles 3 and 4 (the polarity of the voltage of the capacitor 7 in the original

state is shown in brackets). With non-45 excitation load 2

a control signal is supplied to the thyristor 1, resulting in a thyristor .1. on, and the capacitor 6 charges -. c through circuit 14. At that, diode 15 JQ prevents spontaneous locking of thyristor 1 at oscillatory nature of the process of charging the capacitor 6 and discharging this capacitor through the load 2.

If it is necessary to disconnect the load 2, a control pulse is applied to the thyristor 8. As a result of switching on the thyristor 8, a recharge occurs

the capacitor 7 through the thyristor 8 and the choke 10 to the voltage, the polarity of which is indicated on the drawing, without brackets. This continues the process of charging the capacitor 6 through the circuit 14 and the switched on thyristor 1, if the time interval between the moments of supplying control pulses to thyristors 1 and 8 was less than the charging time of the capacitor 6. The specified time interval can be anything, including small. After the process of recharging the capacitor 7 is completed, the thyristor 8 is closed through the thyristor 8 and the choke 10. Next, a control signal is supplied to the thyristor 5, which opens and provides recharging of the capacitor 7 to the voltage of the initial polarity indicated on the drawing in parentheses along the first circuit: 7-5-6-1-9-7i and simultaneously on the second circuit: 7 - 5 - 14 - source - 9 - 7. With a relatively large load current 2, an increase in the current in the primary circuit first leads to the opening of diode 13 as a result of the complete discharge of capacitor 6, i.e. to the formation of the third circuit of the recharge: 7-5-13-1-9-7 instead of the primary circuit, and then to the diode 12 after the current of the thyristor 1 reaches zero, i.e. to the formation of the fourth circuit recharge: 7 - 5 - 13-12-9-7 instead of the third circuit. In the case of a relatively small load current, an increase in the current in the primary circuit first leads to the opening of diode 12 after the current of the thyristor 1 reaches zero, i.e. to the formation of the fifth circuit: 7-5-6-12-9-7 instead of the first, and then to the opening of the diode 13 as a result of the complete discharge of the capacitor 6, i.e. to the formation of the fourth contour instead of p. It is also possible to form a fourth circuit instead of the first one in the case of simultaneous opening of diodes 13 and 12. During further recharging of the capacitor 7 simultaneously through the second and fourth circuits, the current in the fourth circuit starts to decrease and when it reaches the load current 2, the diode 12 is closed. After locking the diode 12, instead of the fourth circuit of recharging the capacitor 7, a sixth circuit is formed:

7-5-13-2- source - 9 - 7. At the time of the recharging of the capacitor 7 until the voltage indicated on the drawing in brackets, the thyristor 5 is closed, after which the key is ready for the next cycle of operation. After locking the thyristor 5 circuit 14 continues to flow current along the circuit 14-11-6-14 under the action of the energy stored in the inductance of the throttles 16, which leads to a partial charge of the capacitor 6 to a certain voltage polarity indicated on the drawing, and accelerates the process of preparing for the following off thyristor 1,

The capacitance of the capacitor 6 is chosen solely because of the need to compensate for the energy loss of the capacitor 7 when it is recharged and therefore substantially less than the capacitance of the capacitor 7. Due to this compensation of the energy loss, the recharging time of the capacitor 7 to the voltage shown in brackets is significantly reduced.

The diode 13 turns off the capacitor 6, from the circuit of the thyristor 1 at the moment of complete discharge of the capacitor 6 and thereby significantly reduces the natural frequency of the third and fourth circuits compared to the natural frequency of the first and fifth circuits. This ensures the fulfillment of mutually contradictory requirements for the speed of the key and the reliability of the switching of the thyristor 1: on the one hand, the process of compaction of the thyristor 1 along the first circuit is accelerated, and on the other, the maximum possible time for securing the locking properties of the thyristor 1 is provided.

Diode 12 eliminates overvoltage at load 2 and provides almost complete independence of the speed of the key from the parameters of load 2.

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Claims (1)

Invention Formula A DC switch containing the first thyristor connected in series with the cathode load between the poles of the power source, the second thyristor, the first capacitor included between the cathodes of the first and second thyristors, the second capacitor, the first output of which is connected to the anode of the second thyristor, the first and second chokes connected to the first terminals of the anodes of the first and second thyristors, respectively, the first diode, shunting the load in the opposite direction, the second and third diodes connected by anodes to the cathodes of the first and the second thyristor, respectively, the first charge circuit of the series-connected third throttles and the fourth diode, connected between the cathode of the second thyristor and the connection point of the load with the power supply pole, characterized in that, in order to improve performance and reliability in operation, a third thyristor was introduced, the cathode of which is connected to the second output of the second droplet, and the anode with the connection point of the second leads of the second capacitor and the first droplet, and the second charge circuit connected between the anode of the second tee the resistor and the point of connection of the load with the pole of the power source, and the cathodes of the second and third. These diodes are connected to the anode and cathode of the first thyristor, respectively.