RU2489764C2 - Electromagnetic current sensor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: electromagnetic current sensor has a magnetic conductor with a control coil, an armature, a main current winding, a fixed contact and a movable contact. The novelty is that the movable contact is connected to the fixed contact and one of the ends of the armature of the current sensor through a disconnection spring and the axis of rotation of the armature is located at the centre of the body of the armature.

EFFECT: high reliability and faster operation.

3 dwg

Description

The invention relates to electrical engineering, in particular to protective switching equipment, and is intended to protect electrical equipment of public transport from short circuit currents and overloads.

Electromagnetic current sensors that turn off when the magnetic flux changes in the magnetic circuit of the current sensor are known from the following sources:

1. A.I. Golubev. High-speed circuit breakers. - M.-L.: Energy, 1964, pp. 23-29;

2. Patent RU No. 57963, 2006

The first source in Fig. 4 p. 25 shows a circuit breaker with an electromagnetic current sensor connected to the circuit breaker contacts through a mechanical latch. The disadvantage of this device is the increase in the trip time of the circuit breaker due to the additional time spent on the sequential movement of the latch elements.

Fig. 5 p. 27 of the same source shows a switch with a holding electromagnetic latch. The disadvantage of this device is the slowdown when the circuit breaker is disconnected due to additional kinematic connections.

According to the second source, the switch contains an electromagnetic current sensor device. This sensor contains a magnetic circuit, an armature, a turn of the main current. When the armature moves, the pusher associated with it pushes the latch of the movable contact. The movable contact under the action of the efforts of the contact pressing spring opens with the fixed contact. From the moment the armature of the current sensor begins to move, some time should pass until the pusher connected firmly with it moves close to the latch. From the moment you hit the latch, the process of releasing the contact node begins, which takes some more time.

Thus, the disadvantage of the presented device is the presence of additional kinematic connections, which increase the trip time of the circuit breaker.

The invention solves the problem of creating a simple in design and reliable in operation electromagnetic current sensor.

The technical result, which is created by the invention, is to increase the speed when the electromagnetic switch disconnects the current switching device.

The essence of the invention lies in the fact that the movable contact is connected to the fixed contact through the disconnection spring, and the axis of rotation of the armature is located in the center of the body of the armature. The connection of the movable contact with the armature of the current sensor through the tripping spring without additional kinematic connections ensures the speed of circuit breaker tripping. Placing the axis of rotation of the armature in the center of the body of this armature reduces the moment of inertia and increases the working area of contacting the armature with the magnetic circuit, which helps to reduce the dimensions of the device while maintaining the technical parameters of the switch. The smaller dimensions and mass of the moving parts of the current sensor also contribute to increased performance when the circuit breaker is turned off.

The invention is illustrated by an example implementation. 1 schematically shows a patentable electromagnetic current sensor in the on position; figure 2 is the same for emergency shutdown, figure 3 is the same for operational shutdown.

The electromagnetic current sensor contains a magnetic circuit 1 with a control coil 2, an armature 3, a main current coil 4, mounted on one of the magnetic core rods 1, a fixed contact 5 and a movable contact 6. An anchor 3 is mounted on a fixed axis 7. One end of the armature 3 is connected to movable contact 6 through the spring 8 shutdown (it is also the spring of contact pressing). A movable contact is mounted on the axis 9 with the possibility of rotation around it.

The closure of contacts 5 and 6 occurs due to the drive of the switch, the device of which is not shown in the figures (this may be an electromagnetic, induction-dynamic, pneumatic or other drive).

When a short circuit current flows, the main current loop 4 induces a magnetic flux in the sensor magnetic circuit 1 (Fig. 2) and the current sensor armature 3 is attracted to the magnetic circuit 1 due to the magnetic field created by the main current coil 4. In this case, the movement of the armature 3 is transmitted through the disconnection spring 8 to the movable contact 6, which immediately opens with the fixed contact 5, turning around axis 9. The switch is ready for re-inclusion.

When the circuit breaker is tripped, it is necessary to apply a current to the control coil 2 (Fig. 3), the direction of which will coincide with the direction of the main current in coil 4 (the directions of magnetic fluxes are shown in figures 2 and 3 by arrows). In this case, the magnetic flux in the magnetic circuit 1 will increase and the armature 3 of the current sensor, rotating around axis 7, will be attracted to the magnetic circuit 1, which in turn will lead to the opening of contacts 5 and 6.

Thus, thanks to this design of the electromagnetic current sensor, the speed of the switching device has been achieved, and the electromagnetic current sensor itself is made simple in design with smaller overall dimensions.

Claims (1)

An electromagnetic current sensor comprising a magnetic circuit with a control coil, an armature, a main current loop, a fixed contact and a movable contact, characterized in that the movable contact is connected through a trip spring to a fixed contact and one of the ends of the current sensor armature, and the axis of rotation of the armature is located in the center body anchors.

Images