SU454600A1 - Device for switching transformer windings under load - Google Patents

Description

one

This invention relates to the field of electrical engineering.

A device for switching branches of transformer windings under load can be used in power supply schemes of industrial enterprises where voltage regulation is required — by switching gears of step-down transformers, for example, in power supply schemes of mine sites, workshops of industrial enterprises, residential settlements and cities.

Devices are known for non-switching branches of transformer windings under load with arc quenching when switching in oil or in vacuum.

In order to increase the reliability and time of switching, the proposed device is equipped with a T-shaped lever, the ends of the symmetric arms of which are connected to the moving contacts of vacuum switches, and the end of the third shoulder is connected to the switch, the contactor and the spring. In order to reduce overvoltages and simplify the device, it is equipped with a discharge.

FIG. I am funny depicted the proposed device; in fig. 2 - possible options for connecting the device to the transformer.

FIG. 1 shows one phase of a transformer 1 with windings. Vacuum chambers 2 and 3 are rigidly fixed on a vertical plane symmetrically with the help of insulators. The stationary contacts of the chambers (in Fig. 1 upper) are suspended by means of traction insulators 4 to the symmetrical ends of the T-shaped lever 5 fixedly mounted on the shaft 6, the ends of which are in bearings having a support 7.

When the pivoting lever 5 is deflected to the right or left, the shaft and the symmetrical ends of the lever rotate respectively, which are used to close or open the contacts of the vacuum chambers. To the bottom

T-arm 5 is attached to the right

a ha of contactor 8 to turn on camera 3,

and on the left is a spring 9. breaker contacts

camera 3 and closing contacts of camera 2.

Normally closed camera contact 2

connects to the + 5% branch of transformer 1, and the normally open contact of camera 3 to the -5% branch. The avalanche voltage detector 10 is connected via fuse 11 to the zero tap (0%) of the transformer and fixed contacts of chambers 2 and 3, to which high voltage is applied.

Pia FIG. 2 shows three possible ways of connecting the device to a transformer. Upper figure corresponds to regulation

voltage within ± 5%, bottom left

within 0% - (+ 5%), lower right - 0% - (- 5%).

The device works as follows.

Suppose that the device is controlled automatically by some parameter, for example, by the magnitude of the load current in the network supplied from the transformer to which the device is connected.

If the network load is small, the contactor 8 (see Fig. 1) is de-energized and the T-shaped lever 5 is tilted to the left by the action of spring 9, while the contact of the vacuum chamber 2 is in the closed position, and the contact of chamber 3 is in the open position.

The high voltage of the network through the chamber 2 is applied to the branch - 5%, which corresponds to a decrease in the voltage in the secondary winding of the transformer by 5%. The avalanche or valve discharger 10 is selected in such a way that the voltage that is generated in the circuit (branch + 5%, chamber 2, discharger 10, fuse 11, branch 0%, turns of the transformer) is not able to pierce the valve and short circuit . This position will be maintained until the amount of current in the monitored network increases to some value to which the automatic circuit is tuned.

As the current increases, the contactor 8 is triggered, the T-shaped lever 5 rotates, the contact of camera 2 is opened and the contact of camera 3 is closed, i.e. the voltage is removed from the + 5% branch and fed to the -5% branch, which corresponds to increase in voltage in the secondary winding of the transformer by 5%. During switching from one branch to another, a moment is created when the contact of chamber 2 is already open, and the contact of chamber 3 is not closed yet, i.e. the power circuit is broken

through vacuum chambers. At this moment, the phase voltage breaks through the discharge 10, through which the load current passes. When the contact of the camera 3 closes, it happens

shunting of the discharge voltage 10, the voltage applied to the discharge voltage, is reduced to the value of the circuit voltage (tap 0%, fuse 11, voltage discharge 10, chamber 3, branch -5%, turns of the transformer), and

the bit is closed.

The process of switching the device in the opposite direction is similar to that described. The presence of a small stroke between the contacts of the vacuum chambers, as well as the design of the apparatus itself, ensures the switching of contacts during a time not exceeding 0.03 sec. It is known that the drawback of vacuum chambers is the current cut-off and (as a result) the appearance of non-overvoltages. In this device, the overvoltage does not increase above the permissible norms and, in addition, contributes to the precise triggering of the arresters and the transmission of the load current through it at the moment of switching.

Subject invention

Claims (2)

1. A device for switching transformer windings under load, containing vacuum switches, a switching contactor and a spring, characterized in that, in order to increase reliability and reduce switching time, it is equipped with a T-shaped lever, the ends of the symmetric the shoulders of which are connected to the movable contacts of the vacuum switches, and the end of the third shoulder is connected to a switching contactor and a spring. 2. The device according to claim 1, characterized in that, in order to simplify the device and reducing overvoltages, it is supplied with a discharge.