SU1695407A1 - Device for heating test of transformers - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to expand the scope. The device contains a single-phase transformer 1, an autotransformer 2 connected to the secondary winding of the transformer 1, two-wire line 3, diodes 4-7, thyristors 8-9, resistors 10-13, capacitors 14-15. The inclusion of the autotransformer 2 in the secondary winding of the transformer 1 reduces the power consumption by returning the energy of the autotransformer to the primary winding of the transformer 1.1 sludge. 44

Description

The invention relates to electrical engineering, in particular to devices for testing transformers.

The purpose of the invention is to expand the scope.

The drawing shows a diagram of the proposed device.

The device contains a single-phase transformer 1, an autotransformer 2, a two-wire line 3, diodes 4-7, thyristors 8-9, resistors 10-13, capacitors 14-15.

The device works as follows.

Changing the load current of transformer 1 is carried out by changing the secondary voltage of the autotransformer 2. Increasing the secondary voltage of the autotransformer 2 leads to an increase in current in the primary and secondary windings of transformer 1, reducing the secondary voltage of the autotransformer 2 leads to a decrease in currents in both windings of the transformer 1 under study.

Thus, it is possible to change the load on transformer 1 from idle to any overload, up to a short circuit. Moreover, the transition of the autotransformer to the energy consumer mode from the network via line 3 is excluded. Diodes 4.5 and thyristors 8.9 do not pass the reverse current. In this case, the thyristors 8, 9 perform the role of a periodic key, closing for the time of the first and opening during the second half period of alternating current.

During the first half period, the thyristor 8 is closed (the key is open), since the diode 6 is closed and there is no reverse voltage on the control electrode. During the second half-period, when a small direct anode voltage appears, the thyristor 8 opens through resistor 12 and open diode 6 and remains open until the alternating current through it decreases to zero. After that, the voltage on the thyristor becomes reverse, and it is locked.

Similarly, the closing and opening of the thyristor 9 occurs, but in the other half-periods, i.e. thyristor 9 is closed while thyristor 8 is open.

During the first (positive) half-cycle, the secondary current of the auto-transformer 2 passes from the clamp and through the open diode 4, the wire of the line 3, the primary winding of the transformer 1 under investigation, the second wire of the line 3, the open thyristor 9 to the terminal b of the vehicle

of the formatter. In this case, the reverse current (from the network to the autotransformer via line 3) cannot pass, the key 8 is open, the diode 4 does not pass the current of the reverse direction.

Similarly, during the second (negative) half-period, the secondary current of the autotransformer 2 passes from terminal b through open diode 5, wire from line 3, primary winding of transformer 1, second wire from line 3, open thyristor 8 to terminal a (key 9 is open).

Shunt resistors 10, 11 are connected between the cathode and the control electrode of the non-lockable thyristors 8.9. The thyristor control electrode circuits include capacitors 14.15 to open the thyristors at the lowest forward anode voltage. Resistors 12, 13 limit the forward current of the control electrode.

Turning on the autotransformer 2 instead of the load resistor allows a significant reduction in the power consumption during testing. Energy is consumed from the network, it is necessary only to cover losses in the transformer windings, since the energy of the autotransformer 2 returns to the primary winding of transformer 1. In this case, the tests are carried out at rated voltages and rated currents of the primary and secondary windings of the transformer under study. Energy losses in transformers at nominal operation are typically around 2%. In the proposed device, taking into account the loss in the autotransformer at the nominal mode of operation, the total loss is 4-5%. Therefore, when testing using the proposed device, the power consumption is reduced by a factor of 20-25 compared with the existing method of transformer direct load.

The device can be used to test single-phase transformers and autotransformers, as well as three-phase transformers. When testing three-phase transformers, it is necessary to turn on each phase of the secondary winding of the tested transformer according to the proposed scheme.

Claims (1)

Invention Formula A device for testing the heating of transformers, in which the secondary winding of the transformer under investigation is connected to the primary winding, is distinguished by This is due to the fact that, in order to expand the phase-shifting device, the application areas included, a parallel transformer autotransformer and a formatter are inserted parallel to the secondary winding of the test subject.