SU942176A1 - Three-rhase device for switching-over taps in the neutral of power transformer - Google Patents

Description

(THREE-PHASE DEVICE OF SWITCHING OF BRANCHES IN NEUTRAL POWER TRANSFORMER

one

This invention relates to electronic. roenergy, in particular to the regulation of transformers under load in neutral.

The known switching device for switching the taps in the neutral of a power transformer, the circuit of which contains a resistor, to the terminals of which are connected the power contacts of the switchable three branches. Yu

The disadvantage of this device is the presence of switching contacts, the negative qualities of which (arising during switching arc, burning) reduce the reliability of the device.

The closest in technical essence to the present invention is a switching device, the circuit of which contains power contacts, resistors and thyristor blocks according to the number of phases of the transformer, and intended to be installed on transformers with any winding connection circuit f2.

However, the known device has a complex structure. In addition, thyristors are expensive elements.

The fact that the bulk of regulated transformers of class kV is manufactured with regulation in neutral indicates that it is unnecessary to use such universal switching devices as mentioned above, and outlines the promising possibility of creating simplified devices intended for regulation only in neutral.

The purpose of the invention is to simplify the design and reduce the cost of the switching device.

This goal is achieved by the fact that in a three-phase thyristor tap changer in the neutral of a power transformer, the circuit of which contains power contacts

switchable leads of three phases, a resistor and a thyristor unit, switchable power contacts of the three phases are connected to one pole of the thyristor block through a resistor and two auxiliary contacts, and to the other pole - through six auxiliary contacts.

The drawing shows a diagram of a thyristor device for switching leads in the neutral of a power transformer.

The switching device circuit contains a resistor 1, to the terminals of which are connected power contacts 2-7, switchable branches 8-13, three phases and a thyristor unit 1A with one of its poles, using auxiliary contacts 15 and 16 connected to resistor 1, and the other pole using auxiliary contacts 17-22. connected to the terminals of the power contacts 2-7 The device operates as follows.

In one fixed position, contacts 2,, 6 are closed, which ensure the connection of transformer windings into a star. Switching to another stationary position is carried out in such a sequence. Contacts 15-17 are closed and the thyristor unit 14 is turned on, at which time a circulating current occurs between the taps 8 and 9.

Then contact 3 closes. The closure of the latter occurs without the formation of an arc, which could arise from contact vibrations at the moment of closure or a consequence of electrical breakdown of the space between the contacts when the contacts approach each other. flows through the contact, control from the thyristor unit is removed.

Contacts 15 and 17 are opened, contacts 16 and 18 are closed, the control of the thyristor unit 14 is turned on. At this moment a circuit is created parallel to pin 2 and it is opened without an arc. Then, control from the thyristor unit is removed, the thyristors are locked, and the circulating current circuit between the taps 8 and 9 is interrupted.

The star of the transformer windings at this transitional moment is formed by connecting the taps 10 and 12 of the phases B and C via contacts 4 and 6 and the tap 9 of Phase A through a resistor and pin 3.

After the switching of the contacts of phase A is completed in the same way, switching of the taps of phase B occurs. In this case, contacts 4, 5, 20, 19, 15, 16 and block 14 of the thyristors, then phases C operate (contacts 16, 15, 6, 7, 22 21 and block 14 thyristors).

The second stationary position of the contactor is such that when contacts 3, 5 and 7 are closed, in many cases there is a need to perform arc-free switching only of the contact to be disconnected, and to turn on the current by the mechanical contact itself (contact wear when switched on is usually much less than when off (.

In this case, the sequence of actions of the contacts and the thyristor block of a friend. Constructive device IB in this case is easier. I Currently, the cost of the thyristor blocks is 40-60% of the cost of the entire switching device. On this basis, the advantage of the proposed solution, which makes it possible to reduce I threefold the number of thyristor blocks in a three-phase switching device, becomes obvious.

Claims (2)

1. Dramomirov T., Khubanov V. Stopal of a voltage regulator. Sophie, Technique, 1971, p. 56-58. 2. USSR author's certificate number 418139, cl. H 01 F 29/04, 196351 J s ;. fe Jl 5s Jl  eleven