Device for controlling three-phase switch built around triacs

FIELD: phase-failure protection of three-phase loads.

SUBSTANCE: proposed control device for three-phase switch built around triacs connected to supply mains phase leads has diode group assembled of two diodes integrated by cathodes and thyristor, all connected through anodes to output terminals of switch, thyristor gate electrode being connected to control unit built around optocoupler whose photothyristor is connected through first limiting resistor to thyristor anode and light-emitting diode anode is connected through anode to cathodes of diode group and its cathode, to neutral bus through variable resistor and second limiting resistor; first and second control buttons; three phase optocouplers whose photothyristors are connected through respective limiting resistors to bridge amplifier output and input is designed for connecting to control junction of respective triac; light-emitting diodes of phase optocouplers are cumulatively interconnected in series, shorted out by second control button, and connected through anode of first light-emitting diode to cathodes of diode group and to first lead of first trigger control button connected by its second lead to cathode of diode whose anode is connected to one of supply mains phase leads, and cathode of third light-emitting diode is connected through load resistor to neutral bus.

EFFECT: reduced heat loss, enhanced reliability of device.

1 cl, 1 dwg

 

The invention relates to electrical engineering and can be popolove to protect three-phase loads from unbalanced mode.

Closest to the proposed to the technical essence and the achieved effect is device control three-phase switch on the triacs (I) (prototype),containing the first group of three United anodes of diodes connected cathode to the respective phases of the network, the second group from the United cathodes of the two diodes and thyristors, connected anode to the output terminals of the switch, and the control electrode of the thyristor is connected to the control unit, made optocoupler, photothyristor which through a current limiting resistor connected to the anode of the thyristor, and led through AC and restrictive resistors connected between the common points of the two valve groups, to which is connected the chain of series-connected trigger of thyristor control electrode which is connected to the first output of the first trigger button control, load resistor, three-phase optoisolators, photothyristor each of which is connected through a current limiting resistor to the output of the bridge rectifier, the input of which is connected to the control transition of the corresponding triac, a second control button, and the second output is erway control buttons connected to the positive terminal of one of the bridge rectifiers through the additional resistor, the second control button bypasses the chain of LEDs of three-phase optoisolators.

The disadvantage of this device is the complexity of the rectifier supplying the input circuits of optocouplers, implemented in the form of a three-phase bridge, the availability of starting a thyristor, which leads to excessive thermal losses on the hedging resistors, reduces reliability.

The aim of the invention is to reduce heat losses, the elimination of the phase control circuits optocoupler trigger thyristor, which increased the reliability of the device.

This goal is achieved by the fact that in the device for controlling a three-phase switch on the triacs connected to the phases of the network that contains the group of gates from the United cathodes of the two diodes and thyristors, connected anode to the output terminals of the switch, and the control electrode of the thyristor is connected to the control unit, made optocoupler, photothyristor through which the first limiting resistor connected to the anode of the thyristor, and the led connected anode to the cathodes of the groups of valves, cathode - to the first output of the variable resistor connected to the second output with the first output of the second limiting resistor, the first and second buttons; three phase optocoupler, photothyristor each of which is connected through the corresponding bounding resist the R to the output of the bridge rectifier, the input is designed for connection to control transition of the corresponding triac, and the LEDs phase optoisolators are connected in series according shunted by a second control button and connected the cathode of the led of the third phase of the optocoupler, through a load resistor to the second output of the second limiting resistor, is put the diode anode connected to one of the phases of the network, and the cathode through the first control button to the cathodes of the group of gates and the anode of the led of the first phase of the optocoupler, the second terminal of the second limiting resistor connected to the zero bus.

The essence of the proposed technical solution is to change the schema of the rectifier supply input circuits of optocouplers, in the exception of the schema trigger thyristor, which allowed to reduce thermal losses in the resistors to increase the reliability of the device.

The drawing shows a schematic diagram of a device. Device to control a three-phase switch on the triacs 1 connected to the network phases a, b, C, contains a group of valves from the United cathodes of the two diodes 2 and SCR 3, connected anode to the source terminals 4-6 switch, and a control electrode of the thyristor 3 is connected and the control unit is made on the optocoupler 7, photothyristor through which the first restrictive cramps the tor 8 is connected to the anode of the thyristor, and it led anode connected to the cathode of a group of valves, cathode via the variable resistor 9 limiting resistor 10 to the zero bus: the first 11 and second 12 button controls, three phase optocoupler 13, photothyristor each of which is connected through a suitable limiting resistor 14 to the output of the bridge rectifier 15, the inlet of which is connected to the control transition of the corresponding triac 1 and the LEDs phase optoisolators 13 are connected in series according shunted by a second control button 12 and connected to the anode of the first led to the cathodes of the group of gates and the first output of the first trigger button control 11, is connected to the second output to the cathode of diode 16 connected anode to one of the phases of the network (A), the cathode of the third led through a load resistor 17 to the zero bus.

The device operates as follows.

In the initial state in the presence of mains voltage three-phase half-wave rectifier formed by two diodes 2 and the thyristor 3, is connected to the output terminals 4-6 switch, and therefore there is no current consumption control unit, the input circuit of phase optoisolators 13 is also de-energized, the triacs 1 are closed.

By short-term pressing of the button 11, the phase And through the diode 16, the button 11 is connected to the input circuits of optocouplers 7 and Asnah optocoupler 13, through which begin to leak currents to the input circuit of the optocoupler 7, controlling the level of the supply voltage through a variable resistor 9 and the second limiting resistor 10 to a zero wire, and to the input circuits of phase optoisolators 13 through a load resistor 17 to the ground wire. Unlocked the photothyristors optocoupler 13, leading to the inclusion of triacs 1 and, consequently, the appearance of a voltage on the anodes of the valves 2,3; at normal mains voltage to turn on photothyristor 7, respectively, of the thyristor 3 and the inputs optocouplers applied three-phase half-wave voltage supporting device is in an enabled state after releasing the button 11. At the precipice of one of the phases of the mains supply or the damage type "break" any of the triacs 1 (e.g., in phase) three-phase half-wave rectifier goes into the mode dvuhpilonnogo straightening with the failure of the rectified voltage is within 60 e. to zero, which leads to the extinction of LEDs phase optoisolators 13 and the locking triacs 1 at the moment of equality of the potentials of the phases b and A.

If necessary, disable the switch button 12, which leads to shunting of LEDs phase optoisolators 13, the locking triacs at the moment of transition currents in phases through zero, and the switch is disabled.

In comparison with the prototype (1) avennue device to control a three-phase switch on the triacs different half voltage, applied to the input circuits of optocouplers and, therefore, twice lower heat losses in the resistors, limiting their current, and connecting the first control buttons 11 to the cathodes of the group of gates 2 through the diode 16 gave the opportunity to remove from the device trigger the thyristor.

Sources of information:

RF patent №2178227, CL N 02 N 7/10, 2000, "Device for controlling a three-phase switch on the triacs".

Device to control a three-phase switch on the triacs connected to the phases of the network that contains the group of gates from the United cathodes of the two diodes and thyristors, connected anode to the output terminals of the switch, and the control electrode of the thyristor is connected to the control unit, made optocoupler, photothyristor through which the first limiting resistor connected to the anode of the thyristor, and the led connected anode to the cathodes of the group of valves, cathode - to the first output of the variable resistor connected to the second output with the first output of the second limiting resistor, the first and second control buttons, three phase optocoupler, photothyristor each of which is connected through the corresponding a current limiting resistor to the corresponding output of the bridge rectifier, the input of which is connected to the control transition corresponding simeto is a, moreover, the LEDs phase optoisolators are connected in series according shunted by a second control button and connected the cathode of the led of the third phase of the optocoupler, through a load resistor to the second output of the second limiting resistor, characterized in that it introduced the diode anode connected to one of the phases of the network, and the cathode through the first control button to the cathodes of the group of gates and the anode of the led of the first phase of the optocoupler, the second terminal of the second limiting resistor connected to the zero bus.



 

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