RU2255392C2 - Device for forced control of reversing electromagnetic contactor - Google Patents

Abstract

FIELD: low-voltage circuit-opening devices for low-voltage switchgear and control gear, and control stations.

SUBSTANCE: proposed device characterized in elimination of electric arc and overvoltage in the course of switching its contacts and in electromagnetic compatibility with electronic and microprocessor units of low-voltage switchgear and control gear has first and second power terminals, STOP, START 1, and START 2 control buttons, auxiliary make and break contacts, starting windings of FORWARD and REVERSE contactors, four-diode bridge rectifier, overvoltage limiters, and current-limiting component.

EFFECT: enhanced reliability and speed of contactor.

1 cl, 5 dwg

Description

The present invention relates to low-voltage apparatus engineering and can be used in low-voltage complete devices (GCC) and control stations using reversible electromagnetic contactors.

A device [1] for controlling a reversible electromagnetic contactor (starter) is used to start, reverse, stop an asynchronous squirrel-cage induction motor, in which it is controlled from the same alternating current network from which the electric motor itself is powered, i.e. The reversing contactor is made with AC electromagnets. The disadvantage of this control device is the relatively low operational reliability, determined mainly by the low operational reliability characteristic of AC electromagnets (loss and breakage of short-circuited turns, fluffing of poles of charged magnetic systems).

In various industries with increased requirements for the reliability of the operation of electrical equipment, electromagnetic devices with direct or direct current control are used. Moreover, the control circuit [2] is identical with the case of engine control using alternating current electromagnets [1]. The control circuit of the reversing electromagnetic contactor contains (Fig. 1) the first 1 and second 2 power terminals for connecting a power supply of constant voltage (constant, rectified, pulsating), the contact of the Stop control button, indicated by the number 3 and connected by one terminal to terminal 1 and the other with a parallel electrical circuit, which includes the forward contactor winding 4 connected in series, the auxiliary contact 5 of the back contactor, contact 6 of the start 1 control button and winding 7 “Back” contactor, auxiliary NC contact 8 of the “Forward” contactor, contact 9 of the “Start 2” control button, making contacts 10, 11 of the auxiliary circuits of the “Forward” and “Back” contactors are connected in parallel, respectively, to the contacts of the “Start 1” and "control buttons Start 2 ". In this case, the free ends of the windings 4 and 7 of the Forward and Back contactors are connected to the second power terminal 2.

The disadvantages of reversing contactors made using DC electromagnets are the increased power consumed by the electromagnets, the consumption of winding copper, electrical steel, the wear of the contact of the Stop button and the overvoltage that occurs when it opens.

The closest in technical essence to the claimed device forcing control of a reversing electromagnetic contactor is a device (figure 2) for controlling a reversing electromagnetic contactor [3], which can be connected to a constant, rectified voltage source. It contains the first 1 and second 2 terminals for connecting the power source, NC contact 3 of the Stop control button, connected between the first power terminal 1 and one end of a parallel circuit composed of series-wound starting winding 4.1 of the Forward contactor, NC contact 5 of the auxiliary the circuit of the “Back” contactor, the making contact 6 of the “Start 1” control button and the starting winding 7.1 of the “Back” contactor, the making contact 8 of the Forward contactor, the making contact 9 of the “Start 2” control button, and other ends ohms connected to the second terminal 2 of the power supply, the closing contacts 10 and 11 of the auxiliary circuits of the contactors "Forward" and "Back", connected by the first terminals to the common connection point of the contacts 3, 6, 9 of the control buttons "Stop", "Start 1", "Start 2 ", and by the second terminals, respectively, to the common point of connection of the make contact 9 of the Start 2 control button with the normally open contact 8 of the auxiliary circuit of the Forward contactor and to the common point of connection of the make contact 6 of the control button" Start 1 "with the normally open contact 5 of the auxiliary circuit contact RA, current-limiting element 12, made in the form of a series connection of the holding windings 4.2 and 7.2 of the Forward and Back contactors, connected according to the starting windings 4.1 and 7.1 of the Forward and Back contactors, respectively, and connected between the common the connecting point of the make contact 6 of the Start 1 control button with the normally open contact 5 of the auxiliary circuit of the Back contactor and between the common connection point of the make contact 9 of the Start 2 control button with the normally open contact 8 of the auxiliary contact circuit and "Next".

The device (figure 2) provides a significant reduction in the power consumed by the electromagnets, the consumption of winding copper and electrical steel. However, there are switching overvoltages that occur in the control circuit, and the demagnetizing effect of the current in the holding windings during the switching process. To start the engine "Forward", contact 6 of the "Start 1" button closes. The current consumed by the device from the power source flows from terminal 1 through the closed contact 3 of the Stop control button, closed contact 6 of the Start 1 control button and flows in two parallel circuits: closed contact 5 of the auxiliary contactor circuit “Back”, starting winding 4.1 forward contactor and current limiting element 12, closed contact 8 of the auxiliary circuit of the forward contactor, starting winding 7.1 of the back contactor. In this case, most of the current consumed from the source flows through the starting winding 4.1 of the Forward contactor. When the current in the winding 4.1 increases to the operating current, the electromagnetic force P _em becomes more opposing R _mx , and the moving forward contactor system "Forward" begins to move from its initial position δ _n (Fig. 3). When the movable system reaches position δ _1, contact 8 opens. Part of the electromagnetic energy stored in the current-limiting element 12 and the starting winding 7.1 is released in the electric arc arising on the open contact 8, which reduces its wear resistance, and partially in the form of electric overvoltages on the current-limiting element 12, contact 8 and winding 7.1. This can cause a breakdown of the insulation of the windings, and is also unacceptable according to the conditions of joint operation of electromagnetic, electronic and microprocessor units in the low-voltage switchgear. Moreover, as can be seen from figure 2, the current flowing through the current-limiting element 12, at this stage creates a demagnetizing magnetic flux in the magnetic system of the contactor "Forward" and, as a result, increases its response time, the duration of the inrush current, causing additional winding heating 4.1. In position δ _{2 of the} movable system, the main contacts of the Forward contactor are closed, and in position δ ₃ - contact 10 of its auxiliary circuit. In this case, the current-limiting element 12 is short-circuited by contacts 6 and 10, through which the demagnetizing current starts to flow again, under the action of the electromotive force of the mutual induction of the windings 4.1 and 4.2. When the contact 6 of the “Start 1” control button is opened (in Fig. 3 this corresponds to the position δ _{4 of the} “Forward” contactor moving system), the current-limiting element 12 and the winding 4.1 are connected in series between the power terminals 1 and 2. The currents in the inductive elements 4.1 and 12 are different in magnitude and direction, which causes bursts of electrical overvoltages on them. In the steady state, the current consumed by the device from the power source is determined by its voltage and the total resistance of the winding 4.1 of the current-limiting element 12, which ensures the normal holding of the moving system in the actuated position of the forward contactor. The winding data of the holding windings 4.2 and 7.2 is calculated in such a way that their MDS is insufficient to ensure the operation of the Forward and Back contactors. When the engine is turned off by opening contact 3 of the Stop control button, an electric arc and overvoltage also occur on winding 4.1 and current-limiting element 12. The same processes occur in the device when the Back motor is turned on by closing contact 9 of the Start 2 control button.

The technical result of the invention is to increase reliability by increasing the service life of the forced control device of a reversing electromagnetic contactor, eliminating the electric arc, overvoltage when changing the switching state of its contacts, electromagnetic compatibility with electronic and microprocessor units of the switchgear, and increasing the speed of the contactor.

The technical result is achieved by the fact that in the forced control device of the reversing electromagnetic contactor, containing the first and second terminals for connecting the alternating voltage power supply, the opening contact of the Stop control button is connected between the first power terminal and one end of the parallel circuit, consisting of a starting circuit connected in series windings of the Forward contactor, the opening contact of the auxiliary circuit of the Back contactor, the closing contact of the Start 1 control button, and the fast winding of the contactor “Back”, the opening contact of the auxiliary circuit of the contactor “Forward”, the closing contact of the control button “Start 2”, and the other end connected to the second power terminal, the closing contacts of the auxiliary circuits of the contactors “Forward” and “Back” connected by the first terminals to the common point of connection of the contacts of the control buttons "Stop", "Start 1", "Start 2", and the second terminals, respectively, to the common point of connection of the opening contact of the control button "Start 2" with the opening contact of the auxiliary circuit on the Forward factor and to the common point of connection of the NC contact of the Start 1 control button with the NC contact of the auxiliary circuit of the Back contactor, a current-limiting element, an additional four-diode bridge rectifier and surge suppressors connected in parallel to the starting windings of the Forward and Contact contactors are additionally introduced Back ", the input diagonal of the four-diode bridge rectifier is connected between the common point of connection of the make contact of the control button" Start 1 "with the make contact auxiliary second circuit contactor "Back" and the common connection point of the switching contact the control button "Start 2" NC contact of the contactor auxiliary circuit "NEXT" and the output of its diagonal is connected a current-limiting element.

The essence of the invention lies in the fact that the additional introduction of two surge arresters, which are connected in parallel to the starting windings of the Forward and Back contactors, and a four-diode bridge rectifier, connected with its input diagonal between the common connection point of the make contact of the Start 1 control button with the opening contact of the auxiliary circuit of the contactor "Back" and the common point of connection of the closing contact of the control button "Start 2" with the opening contact of the auxiliary circuit of the contactor "Forward" and the output of its diagonal is connected a current-limiting element eliminates overvoltage windings and electric arc to break contact device and thereby provides increased durability and electromagnetic compatibility with electronic and microprocessor blocks CLE, an increase in performance when the contactor is activated.

Figure 4 shows the electrical circuit of the proposed device forcing control of a reversible electromagnetic contactor, in which a diode is used as a surge suppressor, connected to the first power terminal by a cathode, to which a positive potential of the power source is supplied.

Figure 5 shows the electrical circuit of the proposed device forcing control by a reversing electromagnetic contactor, in which a circuit composed of diode and zener diode is used in series as an overvoltage limiter. A diode is connected by a cathode to a second power terminal, to which a positive potential of the power source is applied.

The proposed device for forced control of a reversible electromagnetic contactor contains the first 1 and second 2 terminals for connecting the power supply with alternating voltage, the opening contact 3 of the Stop control button, connected between the first power terminal 1 and one end of a parallel circuit composed of serially connected starting winding 4.1 of the contactor "Forward", NC 5 of the auxiliary circuit of the contactor "Back", NO 6 of the control button "Start 1" and the start winding 7.1 contact torus "Back", opening contact 8 of the auxiliary circuit of the contactor "Forward", making contact 9 of the control button "Start 2", and the other end connected to the second terminal 2 power, making contacts 10 and 11 of the auxiliary circuits of the contactors "Forward" and "Back" connected by the first terminals 10.1 and 11.1 to the common connection point of the contacts 3, 6, 9 of the control buttons "Stop", "Start 1", "Start 2", and the second terminals 10.2, 11.2 - respectively, to the common connection point of the make contact 9 of the control button "Start 2" with NC contact 8 of the auxiliary circuit pi of the Forward contactor and to the common point of connection of the make contact 6 of the Start 1 control button with the make contact 5 of the auxiliary circuit of the Back contactor, current-limiting element 12 made in the form of a series connection of the holding windings 4.2 and 7.2 of the Forward and Back "connected according to the starting windings of the Forward and Back contactors, a four-diode bridge rectifier 13 and two surge arresters 14 and 15. Moreover, the surge suppressor 14 in the form of a diode is connected in parallel to the starting voltage Otke 4.1 Contactor "Next", and surge arresters 15 - to the starting coil contactor 7.1 "Back" cathodes to terminal 1 to the positive supply potential. The input diagonal 13.1-13.2 of the four-diode bridge rectifier is connected between the common connection point of the make contact 6 of the Start 1 control button with the normally open contact 5 of the auxiliary circuit of the Back contactor and the common connection point of the make contact 9 of the control button "Start 2" with the make contact 8 of the auxiliary the contactor circuit "Forward", and a current-limiting element 12 is connected to its output diagonal 13.3-13.4.

The proposed device forcing control by a reversing electromagnetic contactor (figure 4) works as follows. To start the motor in the direction of rotation "Forward" by pressing the control button "Start 1", contact 6. closes 6. From the power terminal 1 through the closed contact 6 flows the current consumed by the device, most of which flows through contact 5 and the start winding 4.1 of the forward contactor, the smaller - through the terminal 13.1 of the rectifier 13, the holding windings 4.2, 7.2 connected in series, the terminal 13.2 of the rectifier 13, the closed contact 8, the starting winding 7.1 of the "Back" contactor. The total MDS of the windings included in accordance with the larger contactor "Forward", and it provides an electromagnetic force P _em (figure 3), greater than the opposing force P _MX contactor. The moving system of the Forward contactor is set in motion, while the Back contactor remains stationary. When the movable contactor system "Forward" reaches the position δ ₁ (Fig. 3), its contact 8 opens without an electric arc, since the currents in the windings 7.1, 7.2, 4.2 have the ability to close through the surge protector 15 and the rectifier bridge diodes 13, keeping the direction, and this also eliminates overvoltage on these elements of the device. In position δ _{3 of the} moving system of the Forward contactor, its contact 10 closes, however, the operation mode of the circuit elements remains unchanged. The control button "Start 1" can be released, which will lead to the opening of its contact 6 and the serial connection of the rectifier bridge 13 with the current-limiting element 12 with the starting winding 4.1. In this case, the surge suppressor 14 provides a path for the current flow of the winding 4.1. When the currents in the current-limiting element 12 and the winding 4.1 become equal, the diode surge suppressor 14 is closed. The total winding windings of windings 4.1 and 4.2 ensure reliable retention of the Forward moving contactor system in the actuated position at low power consumed by its electromagnet from the power source. The mobile system of the contactor "Back" remains in the position δ _n , since the MDS of its holding winding 7.2 is less than the MDS response. Turning off the engine by pressing the Stop button is not accompanied by the appearance of an electric arc on pin 3, since the diode of the surge suppressor 14 and all the diodes of the bridge rectifier 13 are almost instantly unlocked, providing a path for the flow of winding currents. This also eliminates the occurrence of switching overvoltages in the device. The operation of the device of FIG. 5 is generally similar to the case described above; the difference lies only in the direction of the flow of currents in the windings 4.1, 7.1 and switching elements.

As surge arresters, a resistor-capacitive circuit, a varistor, etc. can also be used.

Thus, the use of the proposed technical solution provides increased reliability by increasing the service life, speed when triggered and its electromagnetic compatibility with electronic and microprocessor systems NKU.

Sources of information

1. Starters electromagnetic PM12 series. TU 16-89 IGFR.644236.033 TU (p. 135, Fig. 22).

2. Starters electromagnetic PML series. TU 16-91 IHEV.644131.001 TU (p. 120, Fig. 16).

3. RF patent №2118866. The control device is a reversible electromagnetic contactor. Publ. 09/10/98. Bull. No. 25 (prototype).

Claims (1)

A forced control device for a reversible electromagnetic contactor, containing the first and second terminals for connecting an alternating voltage power supply, the opening contact of the Stop control button connected between the first power terminal and one end of the parallel circuit, consisting of the forward contactor starting winding connected in series, opening the contact of the auxiliary circuit of the contactor “Back”, the closing contact of the control button “Start 1” and the starting winding of the contactor “Back” , the opening contact of the auxiliary circuit of the Forward contactor, the closing contact of the Start 2 control button, and the other end connected to the second power terminal, the closing contacts of the auxiliary circuits of the Forward and Back contactors, connected by the first terminals to the common connection point of the button contacts Stop, Start 1, Start 2, and the second terminals, respectively, to the common point of connection of the make contact of the Start 2 control button with the break contact of the auxiliary circuit of the Forward contactor e ”and to the common point of connection of the make contact of the“ Start 1 ”control button with the break contact of the auxiliary circuit of the“ Back ”contactor, a current-limiting element, characterized in that a four-diode bridge rectifier and surge arresters are connected in parallel, connected in parallel to the starting windings of the“ Forward ”contactors and “Back”, the input diagonal of the four-diode bridge rectifier is connected between the common point of connection of the make contact of the control button “Start 1” with the make contact m auxiliary circuit contactor "Back" and the common connection point of the switching contact "Start 2" with the auxiliary circuit normally closed contact of the contactor control button "Next", and in its output diagonal connected current limiting element.

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