SU877640A1 - Device for arcless switching - Google Patents

Description

(54) DEVICE FOR WITHOUT ARC SWITCH

I

This invention relates to electric AC apparatus with arc-free commutation.

A device for arc-free switching is known, comprising a circuit connected in parallel to the contacts of two oppositely connected thyristors, the control electrodes of which are connected via a flexible conductor to the movable contact jumpers 1.

A disadvantage of this device is the construction complexity.

The closest to the proposed technical means and the achieved result is a device of arc-free switching, containing a parallel connected circuit of two oppositely connected thyristors, the control electrodes of which are connected to the secondary windings of the current transformer, the primary winding of which | | 1a is in series with the contacts 2

A disadvantage of this device is reduced reliability due to the low voltage on the thyristors at the initial moment of switching, which makes it difficult to unlock them and can lead to sparking at the contacts, and increased control voltage, which requires special protection.

The purpose of the invention is to increase reliability.

The goal is achieved by the fact that each secondary winding is made of two parts with a different wire cross section, with parts with a large cross section connected in series according to the thyristor circuit.

The drawing shows a diagram of the device.

- Consistently with load 1, contacts 2 and the primary winding of current transformer 3 are included. Parallel to pins 2, a circuit of thyristors 4 and 5 connected in parallel is connected. The secondary windings of transformer 3 of current JS each of two parts 6, 7 and 8, 9. Parts 6 and 8 are power, made of large cross-section and connected in series with a thyristor circuit 4 and 5. Parts 7, 9 of the control, are made with a smaller cross-section wire and through diodes 10 and I, connected to the control electrodes of the thyristors 4 and 5.,

Claims (2)

When the contacts are closed, the sum of the voltages 6 and 8 is applied to the thyristors, and X control electrodes - b, 7 and 8, 9. Before opening the thyristors in the control circuits, current flows depending on the resistance of the control circuit. After the anode voltage reaches the switching voltage, the thyristors open, and a part of the load current flows through them, under the action of which the magnetizing current turns decrease, and the voltage and control current sharply decrease. The current through the thyristors with closed coigates does not exceed 4-6% of the contact current. When the contacts open, their current decreases, causing a decrease in the magnetic flux in the core of the transformer. In the windings of the transformer, an emf is induced, causing an increase in the voltage, and hence the current in the thyristor circuit. An increase in this current accelerates the reduction of the magnetizing amperages and magnetic flux. The process develops an avalanche to disappear magnetic flux. The device can be made as an independent product and be used in conjunction with contact switching devices. An inventive device for arc-free switching, comprising a circuit connected in parallel to the contacts of two anti-parallel connected thyristors, the control electrodes of which are connected to the secondary windings of a current transformer, the primary winding of which is connected in series with the contacts, characterized in that The secondary winding is made of two parts with a different wire cross section, with the parts with a large cross section connected in series according to the thyristor circuit. Sources of information taken into account in the examination 1. USSR author's certificate number 514365, cl. H 01 H 9/54, 1976. 2. USSR author's certificate number 335728, cl. H 01 H 9/54, 1972.