SU851609A1 - Three-phase load protection system - Google Patents

Description

The invention relates to electrical engineering, in particular to devices for the protection and control of three-phase rectifiers.

A device for protecting three-pha load, containing a rectifier connected in series with the thyristor, the power circuit of which is included in the coil of the Executive relay, and an electromagnetic apparatus [1].

The closest to the proposed technical means and the achieved result is a device 15 for protecting a three-phase load, containing a rectifier, thyristor, whose catalog is connected to the actuator relay coil with opening and closing contacts, and the control electrode is connected through a resistor to a rectifier connected to a three-phase voltage source , a starter with a block contact, the power contacts of which are connected between the source and the load, and the starter is connected in series with the starter winding New button [2].

The disadvantages of these devices is their low reliability. thirty

The purpose of the invention is to increase the reliability of the device.

This goal is achieved by the fact that the rectifier is connected to a three-phase voltage source between the power contacts of the starter and the load, and the contact block of the starter and the opening contact of the executive relay, the closing contact of which is connected parallel to the start button, are connected to the thyristor control circuit in series.

The drawing shows a schematic diagram of the proposed device,

The device comprises an input machine 1 of three-phase power supply, with one of the phases “of which power is taken to the stop button 2, connected in series with the start button 3 and the winding of the starter 4, having closing power contacts 5 and in the load circuit 6, and block contact 7, connected on the one hand with a resistor 8 connected between the anode of the thyristor 9 and the output of the three-phase rectifier 10, and on the other hand, with an open contact 1Ϊ of the executive relay 12, which is connected to the control electrode of the thyristor 9, the cathode of which is connected to the winding Executive relay 12, the closing contact 13 of which is connected in parallel with the start button 3.

The device operates as follows.

When you turn on the input power supply 1 and press the start button 3 to turn on the relay, which, closing its power contacts 5, turns on the three-phase load, and block contact 7 through a three-phase rectifier.

10, the resistor 8 and the closed opening contact 11 of the executive relay 12 opens the thyristor 9. Through the open thyristor 9, the executive relay 12 is turned on, which, by blocking the start button 3, with its closing contact 13. keeps the starter 4 in the closed state and, at the same time, breaking its opening contact

11, leaves thyristor 9 open.

In the absence of voltage at least on one of the load phases before or after the power contacts of the starter, the thyristor 9, passing through zero, closes and disconnects the executive relay 12, which with its make contact 13 de-energizes the starter 4, which at the same time completely disconnects the three-phase load, protecting her from developing an emergency.

Upon elimination of the malfunction, the device is started by pressing the start button 3 again. Further, the device operates in the above manner.

Thus, the proposed device provides reliable control and protection against the partial-fauna mode of various three-phase loads of almost any power.

Claims (2)

The invention relates to electrical engineering, namely, to devices for the protection and control of three-phase rectifiers. A device for protection of a three-phase load is known, containing a rectifier connected in series with a thyristor, in the power circuit of which the actuator winding is connected, and an electromagnetic device 1. The device for protection of a three-phase load containing the rectifier is closest to the technical means and the result achieved. the driver, the thyristor, whose TCfti is connected to the coil of the executive relay with the opening and closing contacts, and the control electrode through a resistor is connected to DC converter connected to a source of three-phase voltage wives 1st, with the starter block contact, the power contacts of which are connected between the source and the load, and in series with the winding of the actuator including The Chen actuating button 2. The disadvantages of these devices is their low reliability. The purpose of the invention is to increase the reliability of the device. This goal is achieved by the fact that the rectifier is connected to the three-phase voltage source between the power contacts of the actuator and the load, and the block contact of the actuator and the breaker contact of the executive relay, the closing contact of which is connected in parallel with the start button, are connected in series to the resistor. The drawing shows a schematic diagram of the device proposed. The device contains an input automat 1 of three-phase power supply, with one of the phases “—which power is taken to the stop button 2 connected in series with the start button 3 and the winding of the actuator 4 having the closing power contacts 5 and load circuit b, and a block contact 7, connected on one side with a resistor 8, connected between the anode of the thyristor 9 n and the output of a three-phase rectifier 10, and the other side with the opening contact 11 of the executive relay 12, which is connected Inonii with elektrszhom control thyristor 9, the cathode of which is connected to ovmotkv actuating relay 12 zamykayuschiys contact 13 which is connected in parallel trigger button 3. The device sledunadim manner. When the input power supply 1 is turned on and the start button 3 of the relay is turned on, which, by closing its power contacts 5, switches on the three-phase load, and the auxiliary contact 7 through the three-phase rectifier. 10, a resistor 8 and a closed open contact 11 of the executive relay 12 opens the thyristor 9. Through the open thyristor 9 turns on an executive relay 12 / which, by blocking the start button 3, closes the starter with its contact 13. by means of the contact 13. simultaneously the break contact 11 leaves the thyristor 9 open. In the absence of voltage at least at one of the load phases before or after the power contacts of the starter, the thyristor 9, the zero crossing closes and turns off the executive relay 12, which they closing contact 13 de-energizes the starter 4, which at the same time completely disconnects the three-phase load, protecting it from the development of an emergency. When troubleshooting, the device is started by re-pressing the start button. Subsequently, the device operates as described above. Thus, the proposed device provides ngshezhnoe management and protection against incomplete-phase mode of various three-phase load of almost any power. Claims A three-phase load protection center device containing a rectifier, a thyristor whose cathode is connected to an executive relay coil with open and close contacts, and the control electrode is connected via a resistor to a rectifier connected to a three-phase voltage source, a block contact starter contacts of which are included between the source and the load, with the start button in series with the actuator winding; distinguished by the fact that, in order to increase reliability, the rectifier connected to a three-phase voltage source between the actuator’s power contacts and the load, and a blocking contact of the actuator and a breaker contact of the executive relay, the closing contact of which is connected in parallel with the start button, are included in the thyristor control circuit, Resource information taken into account during the examination 1. Authors certificate USSR 369659, cl. H 02 H 7/09, 1969. 2. USSR author's certificate number 488279, cl. H 02 H 7/08, 1973.