GB2097191A - Power electric circuit switching device - Google Patents

Abstract

On an insulating baseboard 1 having a central opening there are located contact devices 2 arranged in a circle thereon. A rotational electromechanical drive 46 is provided to rotate a selector 39, and an electromagnet 35 is mounted for reciprocating its hollow armature 37 to act on a selected lever or levers 14 to operate (respective) contacts 2. Each lever 14 also drives a respective pin 21 upward and due to a respective coil 30 having been energised a catch 23 is rotated by a spring 25 into a position to engage a roller 22 and retain the pin 21 which also operates auxiliary contact unit 28. When a coil 30 is deenergised its armature is driven by a biasing spring to rock the catch 23 away from the roller 22 and allow a spring 29 to drive the pin 21 and move the lever 14 to open the contacts of the respective device 2. <IMAGE>

Description

SPECIFICATION Electric circuit switching device The present invention relates to a remote control of electric energy consumers, and more specifically is concerned with an apparatus for switching electric circuits.

The invention can be used in apparatus for exerting control over a plurality of electric energy consumers, for instance, group of electric motors in various industries, and in particular in coal mines.

The main object of the invention is to provide a device for switching power circuits, which due to the improved construction of an electromagnetic drive enables a more rapid selective disconnection of the circuit under control.

Another object of the invention is to simplify the construction of the device and the manufacture thereof.

Still another object of the invention is to provide an apparatus for switching power circuits, which takes shorter time for finding a contact of the corresponding circuit.

A further object of the invention is to provide protection of said device against collapse of control.

According to the invention there is provided a device for switching electric circuits, comprising a group of main contacts, a rotational electromechanical drive having a driving shaft and being adapted for rotating the driving shaft through a predetermined angle; auxiliary contacts for switching local control circuits of the device, an electromagnetic drive having an electromagnet for closing contacts and electromagnets for opening contacts, a hollow armature of the electromagnet for closing contacts, mounted on the driving shaft for movement therealong and rotation therewith, an armature of each electromagnet for opening contacts, mounted to reciprocate for opening contacts, a contactor secured on the armature of the electromagnet for closing contacts and having at least one projection to actuate the main contacts with the aid of mechanisms adapted for separately operating contacts and provided with contact fixing devices, each of which fixing devices being connected with one of the armatures of the electromagnets for opening contacts, and auxiliary contacts for switching local control circuits of the device.

Such construction of the device provides for a rapid emergency disconnection of any of the power circuit under control in the case of failure either in the control circuit or in the electromagnet for opening contacts, whereby providing for a protection against a control failure and improving operating characteristics of the device. In addition, the height of the device is decreased by 20%.

It is useful to construct the proposed apparatus so that some of the auxiliary contact pairs be connected with the electromagnets for breaking contacts so as to operate the latter when said electromagnets operate.

Such embodiment of the invention makes it possible to omit the intermediate relays since the electromagnets for breaking contacts, connected with the auxiliary contacts, are similar to these relays as regard their functions.

It is convenient that the electromagnets for breaking contacts be constructed as a zerovoltage release for actuating fixing devices when the coils of these electromagnets are deenergized.

It is expedient that some of the auxiliary contacts connected with the electromagnets for opening contacts be placed in the control circuit of the rotational electromechanical drive.

It is also advisabie that the coils of the electromagnets for opening contacts have spark-resistant characteristics.

It is also expedient that the main and auxiliary contacts, the mechanisms for separately closing contacts and the contact fixing devices be mounted on plug-in modules arranged on a common base plate so that each said module incorporates at least one main contact, at least one auxiliary contact, and the respective mechanisms for separately closing contacts, and a contact fixing device for fixing the contact in position.

Such construction of the apparatus facilitates the manufacture and operation thereof /replacing units, maintenance, adjusting/. In addition, it allows manufacturing various modifications of the device for controlling different number of electric drives, and working on different rated currents, and provides for a high level of unification of all possible modifications.

In the case of controlling three-phase circuits it is useful that each said module incorporate three main contacts and a device for fixing position of contacts be connected, through the mechanism for separately closing contact pairs, with a cross arm connecting movable contact members of the main contacts.

Brief Description of the Drawings Figure 1 shows a power circuit switching device of the invention in a de-energized position; Figure 2 is a top view of the proposed device shown in section along line A-A in Fig.

1; Figure 3 is a fixing device for fixing position of contact, the contact is fixed in its closed position; Figure 4 represents a control circuit of power supply circuits with the use of the proposed apparatus; Figure 5 is a cross-sectional view of a modification of the proposed apparatus; Figure 6 shows a plug-in module having an electromagnet for opening contacts; In a preferred embodiment of the invention the proposed device for switching power electric circuits comprises four panels each made in the form of a disk. The upper insulating panel 1 (Fig. 1) has stationary contact members uniformily distributed in a circle thereon.

In this modification as main contacts 2 use is made of vacuum arc-extinction chambers. The number of the contacts 2 is determined by the number of the circuits under control. This modification of the proposed device is adapted to exercise control over 1 5 singlephase power circuits. The movable contact members of the contacts are connected through flexible conductors 4 to bus bars 5 and 6 which are connected therebetween through jumpers 7 (Fig. 2).

The bus bars are connected with pin jacks 8 (Fig. 1) intended for connecting the device to a supply circuit. Terminals of the stationary contact members 9 of the contacts are also made in the form of pin jacks 1 0. The bus bars 5 and 6 are secured to an intermediate insulating panel 11 on the under side of which are mounted mechanisms 1 2 to operate contacts. The number of these mechanisms corresponds to the number of the contacts 2.

Each mechanism 1 2 comprises a frame 1 3 wherein is disposed a lever 14 mounted on an axle 15 and fitted with pressure rollers 1 6.

The lever 14 is connected, through a bush 1 7 and a pin 18, with a movable contact member 3.

Mounted on the top side of the intermediate panel 11 are contact fixing device 1 9 adapted to fix said contacts in position. The lock 1 9 is a cylindrical body 20 having a spring-loaded rod 21 fitted with a roller 22, and a catch 23 mounted on an axle 24 in an opening of the frame 20 and provided with a return spring.

For the purpose of reducing friction the roller 22 may be replaced with a ball bearing.

For the same purpose the catch 23 is also provided with a ball bearing 26. The rod 21 has a pressure plate 27 being mounted on the outside portion thereof and adapted to operate a micro-switch 28 mounted on the upper insulating panel 1 and used as auxiliary contacts (first group of the auxiliary contacts).

There is also provided a spring 29 of the contact fixing device 19, which spring 29 is adapted to actuate the movable contact members 3 of the contact 2. Each fixing device 1 9 is connected with an electromagnet 30 adapted for opening contacts (Fig. 3) by actuating the fixing device 29 by means of a rod 31 provided with a spring 32 and coupled with the armature of the electromagnet 30.

Each electromagnet 30 incorporates a microswitch 33 serving as auxiliary contacts (second group of the auxiliary contacts) and interacting with a rod 34. In Fig. 1 said electromagnet is shown in a deenergized position.

The working position of the elements of the contact fixing device 1 9 with the contacts in closed position is shown in Fig. 3.

In the above embodiment the electromagnets of the apparatus are constructed in the form of a zero-voltage release. They may also be otherwise constructed, for example in the form of an independent release (not shown).

On the insulating panel 11 there is mounted an electromagnet 35 of a solenoid type adapted for closing contacts. Due to the presence of the fixing device 1 9 the coil 36 of the electromagnet 35 is designed for a shorttime operation and therefore has a small size.

The armature of the electromagnet 35 is made in the form of a hollow cylinder having at its one butt-end a slot 38 and a contactor 39 rigidly mounted thereon.

The contactor 39 is provided with projections 40 to actuate the levers 14. The number of the projection depends on the number of circuits being simultaneously switched and on the type thereof (multiphase, single-phase, d.c. circuits). In the above embodiment of the device adapted for use in single-phase circuits the contactor 39 has one projection. The armature 37 is provided with a return spring 41. The driving shaft 42 is disposed in the openings provided in the contactor 39, and in the frame and armature of the electromagnet 35, and is mounted in ball bearings 43 provided in the upper insulating panel 1 and the lower panel 44. The driving shaft 42 is coupled with the armature 37 by means of a pin 45 passing through the slot 38 provided in the armature 37.Such construction enables rotation of the contactor 39 together with the shaft 42 and reciprocating motion of said contactor 39 together with the armature 37 when the electromagnet 35 operates.

The device for switching power circuits includes a rotational electromechanical drive 46 providing for rotation of the driving shaft 42 through a predetermined angle the value of which is determined by the location of the contact to be actuated (vacuum chamber on the panel 1). In this modification of the device the drive 46 includes an electric motor 47 provided with a reduction gear whose shaft is coupled, through a half-coupling 48, with a setting device 49 adapted to set the angle of rotation of the driving shaft 42, corresponding to the position of the contact to be operated.

The setting device 49 is made in the form of an arm 50 interacting, through rollers 51 mounted thereon, with a limit switch as 52 located in a circle within a frame 53. The number of the rollers 51 is determined by the number of simultaneously operated contacts required to complete a given control circuit.

The arm 50 of the setting device is attached to the half-coupling 54 mounted in ball bearings 55 and rigidly coupled with the driving shaft 42. The setting device is secured on an upper metal panel 56 and is coupled with the driving shaft 42 with the aid of a key 57. The panels 1, 11, 44, and 56 are connected with each other with the aid of three pins 58 located symmetrically in a circle about the centre thereof. The device is further provided with a cylinder having a thread and being adapted for securing the device within a housing of an electrical apparatus and providing for the connection of the pin jacks 8 and 10 with the contact pins of the counter panel (not shown). Mating the pin jacks with the contact pins is accomplished with the aid of guide pins 60.

The device is provided with a connector axsembly 61 for connecting it with control circuits.

Fig. 4 illustrates, as an example of one of the applications of the proposed device, a diagram of exercising control over power circuits with the use of the proposed device. For the sake of simplicity the diagram includes only six circuits.

Shown in Fig. 4 are push buttons "START" 62-67, coils 68-73 of the electromagnets 30 for opening contacts, a transformer 74, push buttons "STOP", diodes 81-86, resistors 87-92, supplementary contacts 93-98 of the contact-opening electromagnets, supplementary contacts 99-104 of the microswitches 28 of the switching mechanisms 42, opening contacts 105-110 of the limit switches, making contacts 111-116 of the limit switches, a rectifier bridge 117, and a button "COMMON STOP". Elements of the power supply unit are not shown in the diagram.

In the above control circuit the coils of the electromagnets 30 are connected in parallel with the transformer winding, with the coil parameters being selected so that the current flowing through the coil does not cause the electromagnet to operate. To cause this electromagnet to operate the coil must be shunted by a diode located on the console (81-86).

According to an alternative embodiment of the invention the proposed device for switching power electric circuits comprises a frame 11 9 (Fig. 5) in the form of a drum formed by an upper and lower discs 120, 1 21 interconnected therebetween with the aid of rods 120.

Plug-in modules 1 23 are uniformly arranged in a circle within the frame 11 9. The movable elements of each said module are connected with a lever 1 24 directed towards the axis of the frame 11 9 and having a roller 125 mounted on its end.

In the central portion of the device is located a contact-making solenoid electromagnet 1 26 comprising a frame 127, a coil 1 28 and an armature 1 29 provided with a return spring 1 30. The frame 1 27 of the electromagnet is attached together with a flange 131 to the upper disc 120.

Rigidly connected with the armature 129 is a contactor 1 32 actuating, through the rollers 125, the levers 124 of the modules 123.

Depending on the number of modules simultaneously switched into circuit the contactor 1 32 may have one or more projections 1 33.

In this modification of the proposed device the contactor 1 32 has only one projection. A driving shaft 1 34 of the device is mounted in ball bearings 135, 1 36 disposed in the flanges 131 and 137 and is passed through the aperture in the frame 1 27 and the armature 129.

The shaft 1 34 is coupled with the armature 129 by means of a pin 1 38 passed through a slot 1 39 provided in the armature. Each plugin module 123 (Fig. 6) is made in the form of a frame comprising an upper base plate 140 and a lower base plate 141 connected with each other with the aid of rods 142. On the outer side of and inside the frame are located switching members and driving mechanisms thereof. The device shown in Fig. 5 is designed for controlling three-phase a.c. circuits and therefore the module includes three main contacts.

As main contacts 2 use is made of arcextinction chambers. The contacts are fastened on the upper base 140 of the module.

Contact terminals of the contacts 2 are made in the form of female connectors 143 and 1 44. The movable contact members of the contacts 2 are connected therebetween with the aid of an insulating cross-arm 145 which is provided with a roller 1 46 introduced into a guide bush 147.

Connected with the roller 146 is the lever 1 24 of a starting drive of the vacuum chambers. This connection is effected through an axle 148. The lever 124 is mounted on a support 1 50 for rotation about the axis thereof by means of an axle 149.

The module is provided with a fixing device 1 9 whose construction is similar to that shown in Figs. 1 and 3, and described above.

The fixing device 1 9 is fastened to the lower base plate 141 of the module. The lower end of the rod of the fixing device is pivoted through an axle 151 (Fig. 7) to the lever 124.

The device shown in Fig. 5 is also provided with a rotational electromechanical drive 46 incorporating the electric motor 47 and the setting device 49, the cylinder with the thread 59 and other elements shown in Figs. 1, 3 as herein described.

The proposed device operates in the follow manner.

By pressing down the push buttons "START" 62-67, for instance 62, the coil 68 (coils 68-73) of the electromagnet 30 is energized with the current flowing through the circuit made up of the transformer 74 secondary, coil 68, push button 62, push button "STOP" 75 (group of the push buttons "STOP" 75-80), diode 81 (group of the diodes 81-86), coil 68, and the secondary of the transformer 74, which causes the electro magnet to operate and to attract its armature, thereby preparing the lock to be raised. Due to the presence of the resistor 87 (resistors 87-92) which shunts the push button 62, the electromagnet 30 remains energized after realesing the push button 62, that is this electromagnet is changed over to a self-holding mode.Instead of the resistors 87-92 use may be made of the blocking contacts of the power circuit, which may also permit operation in a self-holding mode. When the tripping electromagnet operates it actuates the microswitch 33 to thereby close its supplementary contacts 93 (from the second group of the functional contacts 93-98) whereby the electromotor 47 is energized, with the current flowing through the circuit made up of the secondary of the transformer 74, contacts 93, supplementary opening contact 99 (microswitch 28) from the first group of the functional contacts 99-104, opening contact 105 of the limit switch 52 (from the functional group of the contacts 105-110), electric motor 47, and the secondary of the transformer 74.

The motor starts rotating and rotates the driving shaft 42. When the roller 51 reaches the limit switch 52 corresponding to the operated push button and predetermined contacts, the limit switch is operated so that its contacts 105 open to switch off the electric motor 47, while the closing contacts 111 (from the functional group of the contacts 111-11 of of the same limit switch simultaneously connect the coil 36 of the electromagnet 35 in parallel with the secondary winding of the transformer through the bridge rectifier 11 7.

In this case the electric motor stops, the electromagnet 35 operates and the contact 39 connected therewith actuates the lever 14 to thereby operate the thus selected contact, in which case at the end of the travel path the supplementary contact 99 (microswitch 28) is opened to deenergize the coil 36 of the electromagnet 35.

From that instant on the device is ready for finding and operating other contacts in a way similar to that described above. Having been operated each contact is fixed in its actual position by the contact fixing device 1 9. Fixing the contact positions is effected by that the projection 40 of the fixing device presses upon the end of the lever 14 which in turn causes the rod 21 connected thereto to raise and to thereby compress the spring 29 and release the catch 23 which in response rotates about its axis under the action of the spring 25 and locks the rod 21 in its position (Fig.

2).

Opening the required contacts is done by pressing the respective push button "STOP" (75-80), and thereby breaking the supply circuit of the coil (68-73) of one of the electromagnets 30, in which case the latter is deenergized and under the action of its return spring 32 presses with its armature through the rod 31 upon the catch 23 of the fixing device 19, which releases the rod 21, This rod under the action of the spring 29 actuates the lever 14 (Fig. 1) thereby opening the required contact. Simultaneously with the opening of the required contact there opens one of the auxiliary contacts as a result of which the required circuit is prepared for the next possible switching. At the same time one of the auxiliary contacts from the group of the contacts 99-104 (microswitches 28) is closed, thereby also prepearing the required circuit for the next switching.After the push button "STOP" is released the electromagnet 30 does not operate again due to the presence in the circuit of a resistor (87-92), that is the control circuit is broken.

In the case of emergency switching-off of all the consumers under control it is necessary to press the push button "COMMON STOP" which will break the supply circuit of all the coils of the breaking electromagnets thereby opening all the main contacts and de-energizing the circuits of the electric motor 47 and the coil 36 of the electromagnet 35.

A zero-voltage protection of all the groups of power contacts is accomplished in a similar way: in the case of voltage collapse or drop all they are opened by the coils 68-73 of the electromagnets 30. It should be noted that the control circuits with the coils 68-73 are non-sparking due to the use of individual high-resistivity secondary windings of the transformer 74, and parallel connection of the coils 68-73 and adequate selection of their resistance and inductance.

These circuits due to the presence of the diodes 81-86 located on the remote control console are capable of self-controlling like a control circuit. In the case of short-circuiting or breakage, or increase on the resistance of the circuit the electromagnets 30 are disconnected and if they are disconnected they cannot be energized by pressing the push buttons 62-67.

The above circuits may also be non-sparking-proof and without control of their completeness (not shown in Fig. 4). The application of the proposed device is economically efficient.

Estimations has shown that operating the proposed device in the explosion-proof control stations makes it possible to considerably reduce a specific amount of metal, labour consumption, size and cost of control stations and similar apparatus. In this case the size and the cost are reduced due to the following favorable factors: (1) the proposed device occupies by volume approximately 3 times less space as compared with a comparative group of contactors, which also allows the consumption of materials and labour required for the construction of the housing for the apparatus; (2) there is no need of using control units (with intermediate relay) which are still in use.

Each contactor requires only one unit; estimated amount of steel and copper that can be saved constitutes respectively 1 ton and 0.02 ton per one control station of the explosionproof construction.

The application of the proposed device incorporating plug-in modules (Fig. 6) will allow the manufacture of the devices designed for various rated currents and different number of the electric power consumers under control to be simplified.

Considerable economic advantages of the proposed device lies in that it enables easy replacement of individual modules under operating conditions, each of which modules is a complete electrical device provided with power contacts and control elements.

It is also to be noted that the proposed device when in use will contribute in electric energy saving since holding contacts in closed position does not required that the contact closing coils be continuously energized as in the case with contactors. In addition, the device uses only one contact closing coil for a group of circuits under control, which coil is energized during only a rather short period of time.

Claims (8)

1. A device for switching electric circuits, comprising main contacts arranged in a circle; a rotational electromechanical drive having a driving shaft and adapted to rotate the latter to through a predetermined angle; auxiliary contacts for connecting local control circuits of the device; an electromagnetic drive having an electromagnet for closing contacts and electromagnets for opening contacts; a hollow armature of the electromagnet for closing contacts, mounted on the driving shaft for movement along the axis thereof and rotation therewith; an armature of each electromagnet for opening contacts, reciprocating while opening the contacts; a contactor secured on the armature of the electromagnet for closing contacts and provided with at least one projection to operate the main contacts through mechanisms of separately closing contacts provided with contact fixing devices each connected with the armature of one of the electromagnets for opening contacts; auxiliary contacts for connecting local control circuits of the device.

2. A device according to claim 1, wherein part of auxiliary contacts are connected with electromagnets for opening contacts to operate the latter when said electromagnets operate.

3. A device according to any claim 1 or 2, wherein the electromagnets for opening contacts are constructed in the form of zerovoltage releases to actuate the fixing devices when the coils of these electromagnets are deenergized.

4. A device according to any of claims 2, 3 wherein part of the auxiliary contacts connected with the electromagnets for opening contacts are placed in a control circuit of the rotational electromechanical drive.

5. A device accoding to one of any of claims 1, 2, 3, and 4, wherein the electromagnets for opening contacts are provided with sparking-proof coils.

A device according to one of any of claims 1, 2, 3, and 4, wherein the electromagnets for opening contacts are provided with sparking-proof coils.

6. A device according to claim 1, wherein the main and auxiliary contacts, the mechanisms for separately closing the contacts, and the contact position fixing devices are all mounted on a plug-in modules secured on a common base, each said module incorporates at least one main contact and a corresponding mechanism of separately closing contacts and a contact fixing device.

7. A device according to claim 6, wherein for switching three-phase circuits each plug-in module incorporates three main contacts, and a contact fixing device is connected, through the mechanism for separately closing contacts, with a cross-arm connecting the movable contact members of the main contacts.

8. A device for switching electric circuits substantially as herein described with reference to the accompanying drawings.