SU900326A1 - Electroinduction device - Google Patents

Description

The invention relates to electrical engineering, in particular, to high-voltage power transformers and reactors subjected to thunderstorm overvoltages. A radio transformer is known which contains a fixed winding and a capacitive screen located between the primary and secondary windings. The protective winding and capacitive screen allow capacitive currents between windings and between windings and screens to be minimized. For radio devices, the reduction of stray capacitive current is of practical importance. However, such protection is acceptable only for radio transformers that are not connected directly to long-haul transmission lines, from which thunderstorm surges occur. Also known is a transformer containing a high voltage coil winding (HV), electric field leveling elements in the winding insulation with a cooling channel between the high voltage winding and electric field leveling elements. The floor leveling element contains cylindrical electrodes — elements axially mounted along the entire height of the winding. Each element is a cylinder of electrically insulating material, covered with metal foil and insulated from above. The foil layer of each element is galvanically connected by a jumper to the opposite winding overhang. The jumpers are located in the oil channel between the elements and the winding 2. The following shortcomings are characteristic of such a transformer: the presence of bridges between the elements and the inter-ball junctions, the need for their soldering, between adjacent elements there is a voltage equal to the voltage of several coils, insulation at the same time, it has a thickness of several millimeters on the elements, the elements occupy a large volume and reduce the occupancy by active conductors; in the insulation layer immediately adjacent to the elements, there is an increased local electrical intensity. The technology of making the floor leveling element is time consuming. The aim of the invention is to reduce the radial size of the inter-winding insulation by reducing the intensity of the electrical field of the insulation. This is achieved by the fact that in the proposed device the elements of the electric field leveling are made in the form of a single-layer cylindrical winding located concentrically to the windings of high voltage and low voltage (HH) one end of which is galvanically connected to the adjacent end of high winding voltage. The layer of coils wound concentrically with the winding ensures the minimum voltage between adjacent elements (voltage of one coil) thickness of the elements with insulation is equal, respectively, to the radial size of one wire and insulation on it, which can be minimal, jumpers are excluded simplified; the tension in the inter-winding insulation adjacent to the alignment elements decreases (the voltage is distributed evenly along the turns). A trench on the cylindrical surface of the coil layers allows direct winding insulation, such as paper, to be applied to it. FIG. 1 shows the proposed device; in fig. 2 - the same, in conjunction with a known device; in fig. 3 — known device intended for leveling the distribution of pulsed overvoltages inside the winding itself, the cross section (its application and effect does not depend on the elements of the leveling of the electrical tension in the inter-winding insulation); in fig. C - the proposed device for the case of intertwining windings in the coils of the winding, the winding consists of several parts; Fig. 5-13 of the winding pattern in the portions of the winding shown in Fig. ; 9 6 in FIG. And - the scheme of action on the winding VN of the wave of overvoltages; in fig. 15 - the same, the main coils of the HV winding are excluded; in fig. 16 is a graph explaining the physical effect obtained. FIG. 1 coil winding HV consists of working turns 1-100. Layer 1 of turns 1-100 forms the elements of the leveling of the electric field in the inter-winding insulation. Between layer 1 and the high-voltage winding is an oil channel 2, between the layer 1 and the low-voltage winding is interwinding insulation 3. Layer 1 eliminates the influence of protrusions and depressions on the high-voltage winding surfaces that form at the cross-section transitions from a large cross-section wire, for example, transposed and subdivided wires, widely used in high-power power transformers. In the absence of layer 1, the winding irregularities and corners of the coils create pockets of increased electrical strength in insulation 3, which does not allow reducing its radial size and reducing the weight and energy losses in the transformer. Layer 1 creates a flat surface to fit the winding insulation 3, eliminates hot spots in the insulation. One end of layer 1 is galvanically connected to the end of the high-voltage winding, the other end is free. The number of turns in layer 1 corresponds to the number of turns in the HV winding, the voltage difference between the opposite turns of layer 1 and the extreme turns of the HV winding is insignificant. So between coil 8 winding and coil 5 layer voltage is equal to three coil EMF, i.e. 8-5 3. If the winding is of a very high voltage, it also contains a device for equalizing the distribution of the overvoltages within the winding itself, for example a device (Fig. 2). Device 4 is a layer of coils 5 (Fig. H) I wound concentrically winding HV, containing capacitor plates of foil, laminated between each other, forming a mutual electrical capacitance and insulated capacitor paper. In the cross section of the coil, it can be seen that layers of foil 7 and insulation 8 are wound on the cardboard strip 6. As coil 5 is removed from the line output

winding the number of foil layers is reduced to form the required electrical capacitance along the device (there is no galvanic connection between the foil sections). When acting on the winding of lightning overvoltages, device 4 ensures uniform distribution of overvoltages inside the HV winding, and layer 1 ensures the leveling of the tension in the inter-winding insulation 3.

FIG. C shows a winding having an intertwining of turns in coils (interlacing of coils 9-17 in each part of the coils (in Fig.). Alignment of the overvoltage distribution within the winding itself is done here by means of the indicated interlacing of coils.

The physical effect is that the coil layer 1 has an overvoltage distribution the same as in the winding (Figs. 14, 15, 16).

FIG. 14 shows a diagram of the action on the winding HV of the overvoltage wave 18, while the same pulse voltages occur in the HV winding and on layer 1, the voltage 19 between the HV winding and layer 1 is practically absent (the graph in Fig. 16). In this case, the coils of layer 1 have almost the same potentials with the corresponding coils 1-100 of the HV winding without the presence of bridges between them.

To clarify the fact that this positive physical effect is a consequence of a combination of features, in FIG. 15, the main turns of the high voltage winding are excluded and the same overvoltage wave is applied) 8. In this case, in layer 1, significant overvoltages 20 (Fig. 16) occur at its idle end 100. Separate layer 1 has overvoltages as with an isolated neutral. The layer in the proposed winding has overvoltages such as in the main windings of the winding (as applied to the test circuit in Fig. 14, the layer behaves like a grounded end). Position 21 marked all grounded nodes of the transformer.

In layer 1 of turns 1-100, the operating current is absent, the free end is not grounded, however, the potencies of this end (when grounding X HV winding) also has a practically zero value. This is due to the fact that in turns 1-100 the same emf is induced as in turns I-IOO.

The number of turns in the layer, as a rule, is equal to the number of main turns of the winding, but a difference of several turns is permissible.

Claims (2)

1. The patent of Great Britain N 743145, cl. 38/2 /, 1959. 2.Patent UK V 850645, cl. 38/2 /, I960. 9 VN Participate YU // 12 / J /-" 15 sixteen Zwcivu Znacmu 3 parts . Jvacmu NN  parts  parts 17 f nacmeii Figure 5 I. I .1 f.l I I. ih f t in in 18 B 18 8RVM, MNS 16