RU2237305C1 - Forced electromagnet - Google Patents

Abstract

FIELD: manufacture of electric apparatuses, possibly for forced turning on actuating electromagnetic devices of automatic system in oil production, power generation and other branches of industry, particularly in drive units of electromagnetic valves supplied from AC mains.

SUBSTANCE: forced electromagnet includes in addition first and second resistors, fourth capacitor and amplifier. First resistor and connected in series second resistor and fourth capacitor are connected in parallel with outlets of first rectifier. Inlet of amplifier is connected with second resistor and with fourth capacitor. In addition first outlet of first rectifier is connected with first inlet of switching unit; second resistor is connected with common outlet of amplifier; second inlet of switching unit is connected with outlet of amplifier.

EFFECT: increased duration of forcing pulse of electromagnet.

3 dwg

Description

The invention relates to electrical equipment and can be used to force the inclusion of actuating electromagnetic devices of automation systems in the oil, energy and other industries, in particular in actuators of electromagnetic valves, when powered by AC power.

It is known “Device for forcing an electromagnet” (AS USSR N 612290, H 01 F 7/18, published 06/25/78, Bulletin N 23). The device provides forced inclusion of an electromagnet when powered by AC power. The device comprises a transformer with high and low voltage windings, a starting thyristor, a control circuit of the starting thyristor.

The disadvantage of this device is the need to use a special transformer in the power circuit of the electromagnet, limiting the scope of use of such forcing devices.

It is known “Device for forcing an electromagnet” (AS USSR N 838764, H 01 F 7/18, published 06/15/81, Bulletin N 22). The device is designed to control electromagnetic drives in AC circuits. The device contains a controlled key - a mechanically activated contactor, two diodes, a main and an additional capacitor. The boost mode in the device is achieved due to the energy stored in the main capacitor, which is supplied to the electromagnet when the contactor is closed.

The advantage of the device is the simplicity of its circuit.

The disadvantages of the device include:

- large dimensions of the device, due to the need to use the main capacitor of large capacity with high operating voltage;

- the inability to control powerful electromagnetic drives due to the short duration and power of the boost pulse. Known: “Device for controlling an electromagnet” (AS USSR N 845183, H 01 F 7/18, published 07.07.81, bull. N25); “Device for controlling an electromagnet” (AS USSR, N 926730, H 01 F 7/18, published 07.05.82, bull. N 17); “Forced Electromagnet” (AS USSR, N 1141456, H 01 F 7/18, published 02.23.85., Bulletin. N 7). Devices are intended for forced switching on electromagnetic devices of automation systems.

The electromagnet is supplied with AC power in these devices by the voltage of a half-wave rectifier: either through a fully open transistor (in boost mode), or through the same, but partially open thyristor (in steady state). The partial opening mode of the thyristor is set by changing the phase of the alternating voltage at its control electrode.

The advantages of the devices include the simplicity of the circuit.

The disadvantage of the device is the low boost coefficient (the ratio of the power supplied to the electromagnet in the boost modes and keeping the electromagnet in working condition).

This circumstance limits the possibility of using phase-controlled forcing devices for powerful electromagnets.

Closest to the claimed is “Electromagnet with force” (RF Patent N 2037219, H 01 F 7/18, published 09.06.95., Bulletin N16).

The device is designed to control the electromagnetic drives of automation systems. The device comprises a capacitor connected in series with an electromagnet winding; optoelectronic switch of alternating current, made on the basis of a tariff optocoupler, mounted parallel to the capacitor; a resistor optocoupler acting as a delay circuit and connected in series with the input circuit of the thyristor optocoupler; a thyristor installed parallel to the resistor optocoupler and the input circuit of the thyristor optocoupler; elements of the power source of the input circuit of the thyristor optocoupler, resistor optocoupler, thyristor.

At the time of forced switching on of the electromagnetic drive, the thyristor optocoupler shunts the capacitor, thereby providing a large boost current. After a time determined by the delay circuit, the thyristor shunts the input of the opto-thyristor, as a result of which the latter is turned off and the device goes into a steady state, in which the electromagnetic drive is kept in operation due to the current flowing through the capacitor.

The advantages of the device include the simplicity of the circuit.

The disadvantage of this device is the short duration of the boost pulse. In this device, the duration of the boost pulse is determined by the inertia of the resistor optocoupler and does not exceed 0.1 s. The indicated boost pulse duration is not enough to control powerful electromagnets with a large stroke of the moving element (armature).

The task of the claimed device is to increase the duration of the boost pulse.

The task is achieved by the fact that the proposed electromagnet with boost, containing two input terminals for connecting to an AC network, the first and second rectifiers connected to the input terminals respectively through the first and second capacitors, a switching element whose outputs are connected parallel to the second capacitor, a zener diode and a third capacitor installed parallel to the outputs of the first rectifier, an electromagnet winding connected to the outputs of the second rectifier, characterized in that о the device includes: first and second resistors, fourth capacitor, amplifier.

Wherein:

- parallel to the outputs of the first rectifier, a first resistor is connected, a second resistor and a fourth capacitor are connected in series;

- the input of the amplifier is connected to a second resistor and a fourth capacitor. In addition, the first output of the first rectifier is connected to the first input of the switching element, and the second resistor to the common output of the amplifier, the second input of the switching element with the output of the amplifier.

The possibility of increasing the duration of the boost pulse is achieved by using a circuit consisting of the first and second resistors, the fourth capacitor and amplifier as part of the device. In this case, the fourth capacitor and the second resistor perform the function of a timing chain. The charge of the fourth capacitor through the second resistor is used to form a current pulse in the input circuit of the switching element. By changing the values of the fourth capacitor and the second resistor, it is possible to widely change the time constant of the RC chain and, accordingly, the duration of the boost pulse. The first resistor is used to discharge the fourth capacitor and, accordingly, bring the boost device circuit to its original state after a power failure. In this case, the use of an amplifier, on the one hand, makes it possible to charge the fourth capacitor with a current of small magnitude and thereby significantly expand the range of possible adjustment of the pulse duration, on the other hand, to pass enough current through the input circuit of the switching element to change its state in the boost mode.

In addition, the claimed device creates the opportunity to increase the efficiency of the electromagnet with force. This is achieved by using switching elements on the basis of an electromagnetic relay or an optoelectronic switch with symmetric thyristors, which make it possible to supply the electromagnet with a half-wave voltage.

Thus, the introduction of the first and second resistors, the fourth capacitor and amplifier into the device makes it possible to control the duration of the boost pulse over a wide range (from tenths of a second to several seconds)

Figure 1 shows a diagram of an electric electromagnet with boost, figure 2 shows a diagram of a switching element using an electromagnetic relay, figure 3 is a diagram of a circuit using an optoelectronic switch and symmetric thyristors,

The forced electromagnet in figure 1 contains two input terminals for connecting to an alternating current network 1, 2, an electromagnet winding 3, first 4 and second 5 rectifiers connected to the input terminals, respectively, through the first 6 and second 7 capacitors, a switching element 8, a zener diode 9 and third 10 and fourth 13 capacitors, first 11 and second 12 resistors, amplifier 14, amplifier elements, which include the third 15 and fourth 16 resistors, transistor 17.

Variants of circuits of the switching elements shown in Fig.2, 3, contain an electromagnetic relay 18, an optoelectronic switch 19, a symmetric tensor 20, fifth 21 and sixth 22 resistors.

The device operates as follows.

In the initial state, in the absence of voltage at the input terminals 1, 2, the outputs 3 and 4 of the switching element 8 are open, the input circuit of the second rectifier 5 used to power the winding of the electromagnet 3 is connected to the input terminals 1 and 2 through the second capacitor 7.

When applying an alternating voltage to the input terminals 1 and 2 of an electromagnet with a boost, it simultaneously arrives at:

- to the first rectifier 4 through the first capacitor 6;

- to the second rectifier 5 through the second capacitor 7

The value of the first capacitor 6 is selected from the condition of obtaining at the output of the first rectifier current and voltage necessary to control the operation of the switching element; the value of the second capacitor 7 is selected from the condition of reliable retention of the electromagnetic device in working condition, but insufficient to turn it on.

Under the action of the voltage at the output of the first rectifier 4, limited by the zener diode 9, the current of its charge flows through the fourth capacitor 13. The charge time of the fourth capacitor 13 is determined by the resistance values of the second resistor 12 and the resistance between the input and the common output of the amplifier. The voltage drop that occurs in this case at the second resistor 12 is fed to the input of the amplifier. As a result, the circuit output 1 of the first rectifier, the first 1 and second 2 inputs of the switching element, output 3 and the common output 2 of the amplifier 14, the output 2 of the first rectifier current flows. Under the action of this current, if its magnitude is sufficient to change the state of the switching element 8, its output terminals 3 and 4 are closed. The outputs of the switching element are closed either by the contacts of the electromagnetic relay or by symmetrical tariffs. In this case, the switching element 8 shunts the second capacitor 7, ensuring the flow through the input terminals 1 and 2 of the device, the second rectifier 5 and the winding of the electromagnet 3 of the boost current. The magnitude of the boost current is determined by the resistance of the winding of the electromagnet 3. As the fourth capacitor 13 charges, its charge current drops, the voltage at the input of amplifier 14 decreases. Accordingly, the control current between the first and second inputs of the switching element 8 also decreases. At a time when this current becomes insufficient for holding outputs 3 and 4 of the switching element 8 in the closed state, they open. Force mode ends. Through the input terminals 1 and 2 of the device, the second capacitor 7, the second rectifier 5, the winding of the electromagnet 3 flows the current holding the electromagnet in working condition. The value of the holding current is determined by the capacitance of the second capacitor 7. When the voltage at the input of the device is turned off, the current in the winding circuit of the electromagnet becomes zero, the actuating electromagnetic device returns to its original state. The fourth capacitor 13 is discharged in a circuit formed by the first 11 and second 12 resistors. After the discharge process is complete, the device is ready for a new inclusion of the electromagnet.

The current flow time of the forced inclusion of the electromagnet is determined by the charge time of the fourth capacitor 13; gain of the amplifier; the magnitude of the control current between the first and second inputs of the switching element, necessary to close its output terminals 3 and 4. There are various versions of the switching element and amplifier. In an example of a practical implementation of the device, switching elements are used, made according to the circuit with the electromagnetic relay 18 shown in FIG. 2, and according to the circuit with an optoelectronic switch 19 and symmetric transistors 20 at the output shown in FIG. 3. Considering that the control currents of the switching element for its various designs are different, it is possible to change the duration of the boost pulse by selecting the circuit of this element.

The inventive device was used to control a gas shutoff valve type SVMG with the following main characteristics:

- pressure of the working medium - 0.1 MPa;

- anchor stroke - 14 mm;

- bore diameter - 50 mm;

- power supplied to the valve at the moment of switching on - 135 W;

- the power consumed by the valve in steady state is less than 1 W.

The forced electromagnet was made using the following components:

- the electromagnet 3 is made of PEV-1 wire with a diameter of 0.16 mm, the number of turns is 6300, the resistance of the winding is 360 Ohms;

- the first 6 and second 7 capacitors - K73-17-400 V-0.47 uF,

- the first rectifier 6 - diode bridge RB 157;

- second rectifier 7 - diode bridge RS205;

- Zener diode 9 - Zener diode D814D;

- the third 10 and fourth 11 capacitors - K50-35-16V-10.0 microfarads;

- the first resistor 11 is a resistor C2-33-0.125-510 kOhm ± 5%;

- second resistor 12 - resistor C2-33H-0.125-100 kOhm ± 5%;

- amplifier 14 consisting of: transistor 17 - transistor KT 315, fourth resistor 15 - resistor C2-33H-0.125-10 kom ± 5%, fourth resistor 16 - resistor C2-33H-0.125-2 Ohm;

- a switching element 8 based on an optoelectronic switch and symmetric thyristors, consisting of: optoelectronic triac 19-AOU160A, fifth resistor 21-C2-33-0.25-510 ± 5%, sixth resistor 22-C2-33-0.25-1kom . ± 5%, symmetric thyristor 20 - triac ТС 106-10;

- a switching element based on electromagnetic relay 18 - relay IV12S-KT.

The inventive device provides the ability to change the boost time from 0.1 to 10 s.

Claims (1)

Forced electromagnet containing two input terminals for connecting to an alternating current network, first and second rectifiers connected to input terminals, respectively, through the first and second capacitors, a switching element, the outputs of which are connected in parallel to the second capacitor, a zener diode and a third capacitor installed parallel to the outputs of the first rectifier, an electromagnet winding connected to the outputs of the second rectifier, characterized in that the first and second resistors are introduced into the device, a fourth a capacitor, an amplifier, a first resistor is installed in parallel with the outputs of the first rectifier, a second resistor and a fourth capacitor are connected in series, the input of the amplifier is connected to a second resistor and a fourth capacitor, in addition, the first output of the first rectifier is connected to the first input of the switching element, and the second resistor to the common output of the amplifier, the second input of the switching element is connected to the output of the amplifier.

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