RU112493U1 - ELECTROMAGNETIC DRIVE - Google Patents

Abstract

An electromagnetic drive containing an electromagnet coil, a rectifier diode bridge, a contact, characterized in that the first and second opening contacts are introduced, a current limiter for the electromagnet coil, and in the diagonal of the rectifier diode bridge connected to the electromagnet coil, in one of the arms forming this diagonal, the first NC contact is connected in series with the diode, and in the other arm adjacent to the specified shoulder of this diagonal, the current limiter of the electromagnet coil is connected in series with the diode, shunted by the second NC contact.

Description

The utility model relates to electrical engineering, in particular, to electromagnetic drives of switching devices, such as vacuum contactors or circuit breakers, using electromagnetic drives, consuming high currents when turned on, and consuming low currents when holding them for a long time, or using mechanical latches.

Known electromagnetic drive (B.E. Kotz. "Forced DC electromagnets. Energy", 1973, p. 9, Fig. 2, circuit 3), in which the electromagnet coil and ballast are connected in series to a constant voltage power supply a resistor shunted by a bipolar transistor, in the base circuit of which there is a timer in the form of an RC circuit. When the drive is turned on, the electromagnet coil connects directly to the power source through the transistor that opened by an operational signal and develops the maximum electromagnet force. After the timer setting time, longer than the drive on time, the transistor closes and the source voltage is applied to the electromagnet coil, limited by the voltage drop across the ballast resistor; this mode corresponds to the drive position that has been switched on for a long time. The drive shuts off when the supply voltage is removed.

The main drawback of the drive is the large unproductive consumption of electricity on the resistor and its heating, which requires effective cooling, the use of a powerful transistor.

A device is known for the forced electromagnetic drive of the switching apparatus (patent RU 2195732 C2, IPC H01F 7/18, H01H 47/32, published. December 22, 2002), which contains an electromagnet coil, a diode shunting this coil, a transistor, a timer, a rectangular pulse generator, contact switch and on / off switch. When the electromagnetic drive is turned on, the switching contact opens the transistor and the electromagnet coil is connected to a constant or rectified voltage source; at the end of turning on the electromagnetic drive, the switch connects the base of the transistor to the square-wave generator and the minimum current flows through the coil of the electromagnet, holding the armature of the electromagnet in the pulled position, and the electromagnetic drive in the on position.

The disadvantage of an electromagnetic drive is a complex control circuit with a powerful transistor, timer and a rectangular pulse generator on microcircuits, which also leads to a decrease in the reliability of the drive.

The closest analogue (prototype) to the proposed technical solution is the electromagnetic drive of the circuit breakers (patent RU 2074438 C1, IPC Н01Н 33/42, Н01Н 33/66, Н01Н 33/59, published February 27, 1997), which contains an electromagnet coil, a rectifier diode bridge , contact in the form of an electronic key. Vacuum interrupter chambers (VDK) are switched on by an electromagnetic drive from an alternating voltage source through a rectifier diode bridge using an electronic key. In the on position, the electromagnetic drive is fixed by a mechanical latch, knocked down by a tripping electromagnet when the drive and switch are turned off.

A significant drawback of the electromagnetic drive is the use of a mechanical latch and a tripping electromagnet, which not only complicates the design and increases the dimensions of the electromagnetic drive, but also makes it less reliable and durable in use.

The technical task of the utility model is the creation of an electromagnetic drive that allows you to use the switching devices from the VDK for large rated and shock currents, requiring high traction forces of the electromagnet, and keeping the electromagnetic drive in the on position with minimal energy consumption.

The technical result of the utility model is to simplify the circuit of the electromagnetic drive as much as possible, increase its reliability, and expand its functionality, since switching devices with high-voltage electric motors are switched on for high rated and shock currents, which require high traction forces of the electromagnet, and the electromagnetic drive is kept in the on position with minimal energy consumption .

The problem is solved due to the fact that the first and second breaking contacts, the current limiter of the electromagnet coil are introduced into an electromagnetic drive containing an electromagnet coil, a rectifier diode bridge, a contact. In the diagonal of the rectifier diode bridge connected to the coil of the electromagnet, in one of the arms forming this diagonal in series with the diode, the first opening contact is connected. In the other arm adjacent to the indicated arm of this diagonal, a current limiter of the electromagnet coil, shunted by the second NC contact, is connected in series with the diode.

The proposed technical solution is illustrated by drawings and diagrams, where:

figure 1 presents the electrical circuit of the electromagnetic drive (in the off position) with a zener diode as a current limiter of the coil of an electromagnet;

figure 2 shows the use of a nonlinear resistor as a current limiter of the coil of an electromagnet;

figure 3 shows a linear resistor as a current limiter of the coil;

figure 4 presents a diagram of the voltage applied to the coil of the electromagnet: on the left - when the electromagnetic drive is turned on, on the right - in a long holding mode;

figure 5 presents a diagram of the current in the coil of the electromagnet: on the left - when the electromagnetic drive is turned on, on the right - in a long holding mode.

The device (figure 1) contains:

1 - source of alternating voltage;

2 - coil of an electromagnet;

3, 4, 5, 6 - diodes,

7 - current limiter of the coil of an electromagnet;

8 - the first NC contact;

9 - second NC contact;

10 - contact.

In figure 4 (right), the shaded region corresponds to the voltage applied to the coil of the electromagnet 2 in continuous operation after opening the first 8 and second 9 opening contacts.

In figure 4 is indicated:

U _m - the amplitude value of the voltage of the source of alternating voltage 7;

U ₁ - voltage of the current limiter of the coil of the electromagnet 7, corresponding to a zener diode or non-linear resistor;

t ₀ is the closing moment of the switching contact 10;

t ₃ , t ₄ - the beginning and end of the voltage pulse on the coil of the electromagnet.

Figure 5 is indicated:

t ₀ is the closing moment of the switching contact 10;

t ₁ - moment of stop of the armature of the electromagnet;

t ₂ - the moment of opening of the first 8 and second 9 opening contacts;

i ₁ , i ₂ - the minimum and maximum value of the current of the coil of the electromagnet 2.

In the device (Fig. 1), a rectifier bridge formed by diodes 3, 4, 5, and 6 is connected to an alternating voltage source 1. One diagonal of the rectifier bridge is connected to an alternating voltage source 7 through terminal 10. Another diagonal of the rectifier bridge is connected to an electromagnet coil 2 One a pair of adjacent shoulders of this diagonal - with diodes 3 and 4 - shunt the coil of electromagnet 2. Another pair of adjacent shoulders of this diagonal is formed by diodes 5 and 6.

In the arm of the rectifier diode bridge with diode 5, the first NC contact 8 is connected in series, and in the adjacent arm, with diode 6, the current limiter of the electromagnet coil 7 is connected in series, shunted by the second NC contact 9. Diodes 3 and 4 perform the function of bypassing the electromagnet coil in electromagnetic holding mode drive in the on position.

The device operates as follows.

When an operational command is issued to turn on the electromagnetic drive - closing contact 10 - through the diodes 3, 4, 5 and 6 of the rectifier diode bridge and the first 8 and second 9, the NC contacts to the electromagnet coil pass fully rectified half-waves. In this case, the electromagnet develops a maximum traction force exceeding the total force of the disconnecting springs and preloading the contacts of the vacuum arcing chambers (VDK), turning on the electromagnetic drive and the switching device. A few milliseconds after the armature of the electromagnet stops - time t ₁ (Fig. 5) - the first 8 and second 9 disconnect contacts are disconnected - at time t ₂ . After that, cut off half-waves of the voltage of the AC voltage source 1, additionally limited by the voltage drop at the current limiter of the coil of the electromagnet 7, begin to be applied to the coil of electromagnet 2. In this case, the current passes through the coil of the magnet through diode 6, the current limiter of the coil of electromagnet 7 and diode 4. When changing polarity voltage to the coil of electromagnet 2 is not supplied. In this long periodic steady-state mode at negative half-waves, the current in the coil of the electromagnet decreases approximately exponentially through diodes 3 and 4 to the minimum value of i ₁ . At the next positive half-wave, the current rises again to the maximum value of i ₂ . The minimum current i ₁ provides the necessary magnetic flux, and consequently, the holding force of the armature of the electromagnet in the pulled position and the switching apparatus in the on position, overcoming the forces of the disconnecting and preload springs in devices with VDC.

The electromagnetic drive is switched off by operative opening of contact 10. In this case, at the initial stage of the movement of the armature of the electromagnet, the first 8 and second 9 opening contacts are closed, preparing the circuit of the electromagnetic drive for the next inclusion.

The first NC contact 8 and the current limiter of the coil of the electromagnet 7 with the second NC contact 9 can be located anywhere in the rectifier diode bridge, but must be mutually in the adjacent shoulders of the diagonal of this bridge connected to the magnet coil.

One of the advantages of the proposed electromagnetic drive is the facilitated contact switching due to pauses in the power supply circuit of the electromagnet coil during negative half-waves.

When using a nonlinear resistor as a current limiter for the coil of an electromagnet 7 (Fig. 2) with a voltage-independent voltage characteristic in the operating range, the nature of the voltage curve will be similar to the zener diode shown (Fig. 1). When using a linear resistor (figure 3), the voltage curve on the coil of the electromagnet 2 will correspond to the full half-waves of the source of alternating periodic voltage, but a limited voltage drop across the resistor. The nature of the current curve will be the same for all types of current limiters of the coil of the electromagnet 7.

The proposed utility model expands the functionality of the electromagnetic drives of switching devices with VDK, because it not only implements the ability to turn on such devices at high rated and shock currents, requiring high traction forces of the electromagnet, but also allows you to keep the electromagnetic drive in the on position with minimal energy consumption.

The electromagnetic drives of switching devices with VDK for medium voltage and rated currents up to (1000 ÷ 1600) A must develop great efforts - (800 ÷ 1200) N - when turning on at the moment of closing the VDK contacts with a large working working gap remaining in the drive’s electromagnet. This requirement is ensured by the use of a rectifier diode bridge, which gives maximum use of the power of an alternating periodic voltage source, in particular, an industrial frequency source. When holding the electromagnetic drive in the on position, the working gap in the electromagnet is minimal or equal to zero, and a small magnetization current of the electromagnet is required to keep the drive in the on position. The utility model makes it possible to use part of the rectifier diode bridge in the holding mode by using additional simple and reliable elements: one current limiter of the electromagnet coil in the form of a zener diode or a linear or non-linear resistor and two NC contacts operating in light mode. At the same time, the scheme of the electromagnetic drive and its entire design are greatly simplified.

The best results of the proposed device will be at the maximum time constant of the coil of the electromagnet, several times longer than the half-period of the supply alternating periodic voltage, which, as a rule, is performed in the coils of electromagnetic drives of switching devices powered by a voltage of industrial frequency 50 Hz, in which the time constant exceeds (30 ÷ 40) ms.

The proposed device has been successfully tested on vacuum contactors and circuit breakers for 10 kV and 1000A and with an effort to compress the VDK contacts to 1200 N.

Sources of information taken into account when preparing the application:

1. - B.E. Kotz. “Forced DC electromagnets.” “Energy”, 1973, p. 9, fig. 2, scheme 3

2. - Patent RU 2195732 C2, IPC: H01F 7/18, H01H 47/32, published. 12/22/2002.

3. - Patent RU 2074438 C1, IPC: Н01Н 33/42, Н01Н 33/66, Н01Н 33/59, published on 02.27.97.

Claims (1)

An electromagnetic drive comprising an electromagnet coil, a rectifier diode bridge, a contact, characterized in that the first and second NC contacts are introduced, an electromagnet coil current limiter, moreover, in the diagonal of the rectifier diode bridge connected to the electromagnet coil, in one of the arms forming this diagonal, the first opening contact is connected in series with the diode, and in the other arm adjacent to the indicated shoulder of this diagonal, the current limiter of the electromagnet coil is connected in series with the diode, shun with a second NC contact.