SU99154A1 - Device for automatic regulation of the voltage in the AC circuit - Google Patents

Description

The subject of the invention is a device for automatically regulating a voltage in an alternating current circuit upon a change in load, consisting of two successively decreasing transformers with unequal transformation ratios. One of the transformers has a DC magnetizing winding to automatically change the overall transformation ratio of the device with a change in load current due to the redistribution of the primary voltage between transformers.

In the known devices of this type of submagnetics, the winding is located on a transformer having a lower transformation ratio, and in order to increase the secondary voltage, its impedance during the control process must increase (in order to transfer most of the primary voltage to this transformer). Therefore, in such devices, the magnetizing current is maximum at idle and decreases in the course of voltage regulation, which is why, in addition to common voltage drops in copper and device scattering reactivity, there is an Enge and an additional internal voltage drop that limits the range of regulation tension

A distinctive feature of the proposed O-o device is the completion of an auxiliary transformer, the load, its DC winding bias, with a greater transformation ratio than the main one. Since, in order to increase the secondary voltage, it is necessary to increase the magnetizing current, the bias winding of the auxiliary transformer is on according to a scheme that provides an increase in the magnetizing current with increasing load.

A device made in this way allows the internal voltage drop (decreasing with increasing magnetization) to be reduced in transformers, in order to increase the range of voltage regulation and use the device not only with active but also inductive loads.

In the case of using the device in a three-phase system according to the invention, in order to ensure symmetry of the AC voltage curve, 11ed.1, the main transformer EXT-EYER with the pin core core and the windings of this transformer are connected according to the zigzag scheme.

FIG. 1, 2 and 3 are the electrical circuits of the device made in accordance with the invention when it is used in single phase and three phase systems.

FIG. 1 shows a schematic of a device for single phase pricing. The device consists of two transformers connected in series with both primary and secondary sides. Transformer transformation ratios are different, and the transformation ratio K of the auxiliary (adjusting) transformer TV is greater than the transformation ratio K of the main transformer TO.

Auxiliary transformer for a single-phase circuit is made with an W-shaped core to ensure the symmetry of the voltage curve is provided with an O / 7 direct current iodomagnetic winding fed through a rectifier B from the transformer T, connected in series to the wire cutting on the secondary side.

In the absence of a load on the secondary side of the transformers, a constant magnetization is completely absent, and the applied voltage Uj is distributed in proportion to the complex resistances of the magnetizing circuits of the TV and TO transformers:

 and / Z where and / and Z is the primary voltage and impedance of the transformer TV; U / and the same for transformer TO.

As the load from the secondary side of the transformers increases in proportion to the load current, the permanently-bias current of the auxiliary transformer increases. Wherein . the impedance of the magnetizing circuit of the auxiliary transformer Z decreases, resulting in the redistribution of the primary voltage applied to the primary windings of the transformers TB and TO and their ratio changes.

Due to the difference in the transformation ratios of the individual transformers (L-adjusting and K-main), the secondary voltage Us, which is the sum of the secondary voltages LJ / and the ultrasonic of the individual transformers, also changes with increasing load.

The total transformation ratio Ktotal of the device will change with a change in I between its limiting values by the transformation coefficients of the individual transformers K and

 QC (1 + e)

G total // // S

Since an increase in the total secondary voltage is associated with a decrease in the impedance Z of the magnetizing circuit of the auxiliary transformer, i.e., with the reduction of the additional internal voltage drop, the device has large control capabilities and the control range does not depend much on the power factor.

FIG. 2 shows a diagram of a device for a three-phase circuit.

The control transformer is made up of three single-phase transformers with a W-shaped core, the AC half windings of which are connected in series.

FIG. 3 shows a diagram of a device for a three-phase network with an adjustment transformer having a five-core magnetic circuit.

To equalize the operating conditions of all three phases of an alternating current, the direction of a constant flow in the middle three rods is the same and opposite to the direction of the constant flow in the two extreme rods. The symmetry of the secondary voltage curve in this case is created by the opposite direction of the current in the ac windings of the alternating current (the half windings are connected oppositely), for which the primary windings of the auxiliary transformer are connected in a zigzag circuit.

Subject invention

Claims (2)

1. An apparatus for automatically regulating a voltage in an alternating current circuit consisting of two successively lowering transformers connected with different transformation ratios and a direct current biasing winding on one of the transformers for automatically changing the overall transformation ratio ycT of a variable with load current due to the redistribution of the primary voltage between transformers, characterized in that, in order to increase the range of regulation An auxiliary transformer arranged to bblschim transformation coefficient than the base, and its winding is enabled by a bias circuit providing a bias current increase with increasing load. 2. An apparatus according to claim 1, composed of three-phase transformers for use in a three-phase system, characterized in that, in order to ensure the symmetry of the AC voltage curve, the auxiliary transformer has a five-core core and windings of this transformer are connected in a zigzag pattern. be FIG 2 7 " (th 7 © .4