RO116141B1 - Method for power supply of low voltage consumers - Google Patents

Abstract

The invention relates to a method for power supply of low voltage consumers, by switching the 0.4 kV distribution systems to a higher voltage, up to maximum 1 kV which characterizes the maximum level of low voltage, with a view to improving the technical and economical efficiency and quality index of the electric power. The method consists in using a power transformer (1) with a transformation ratio corresponding to the new voltage of the distribution network, while maintaining the structural elements of the transformation station and of the low voltage electric network, a distribution box (2), phase conductors (3) and earth conductors (4), supplying the monophase consumers with 230 V by means of a monophase transformer (5), and the three-phase consumers with 400 V by means of a group of monophase transformers in a three-phase mounting or by means of a three-phase transformer.

Description

The invention relates to a method of supplying electricity to low voltage consumers, by passing the operation of the distribution networks of 0.4 kV at a higher voltage, up to the limit of 1 kV, which characterizes the maximum level of low voltage, in view improving technical-economic performance and electricity quality indicators.

For this purpose, the method of supplying consumers electricity from distribution networks, through overhead power lines or 0.4 kV cable is known. The electricity supply of the 0.4 kV distribution network is made from the medium voltage network (6-20) kV, through a transformer station of (620] kV / 0.4 kV.

This method of electricity distribution has the following disadvantages:

- limiting the lengths of use of 0.4 kV power lines to relatively small values (400-800 m);

- realization of a large number of transformer stations and medium voltage electrical lines, in order to obtain quality indicators of electricity and the economic functioning of the distribution network 0.4 kV;

- the impossibility of connecting new consumers or expanding the network, due to high voltage drops, exceeding the admitted voltage drop;

- high losses of power and active electricity, due to the n value; · limited section of conductors used, in particular, for aerial electric lines of 0,4 kV;

- the impossibility of achieving the safety sensitivity of fuse protection, given the low values of the single-phase short-circuit currents and the high values of the load currents.

The problem solved by the invention is that of carrying out a method of electricity distribution, by means of the electrical networks in the air or by cable of 0.4kV, by passing their operation to a higher voltage, obtaining technical-economic performances and indicators quality of electricity, superior to the existing method.

The method of supplying electricity to low voltage consumers consists in the use, for low voltage distribution electricity networks, of a voltage higher than the current of 0.4 kV, up to the upper limit of 1 kV, which characterizes the maximum low level. voltage, by using a power transformer with a transformation ratio corresponding to the new voltage of the distribution network, while keeping the other constructive elements of the transformer station and of the low-voltage electrical network.

Electricity supply to single-phase consumers, at 230 V operating voltage, is performed by means of single-phase transformers, and by three-phase consumers at 400 V operating voltage, it is achieved through a group of single-phase transformers in three-phase installation or a to a three-phase transformer.

The invention has the following advantages:

- it is simple, easy to execute, allowing the use of known materials and technologies;

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RO 116141 Bl

- requires lower investment and operating-maintenance costs, obtaining the necessary quality (voltage) indicators, compared to the method of constructing new 20 kV power lines and 20 / 0.4 kV transformer stations, for creation of new injection points in the 0.4 kV network;

- reduces the effective value of voltage drops in electrical lines; 50

- reduces the losses of power and active electricity in the power lines;

- allows to increase the value of the power transmitted on the electric lines for the same economic density of current;

- ensures the sensitivity of the protection of the electrical lines, by using fuses of lower nominal values. 55

The following is an example of an embodiment of the invention, for supplying single-phase and three-phase consumers from the distribution grid operating at a nominal voltage higher than the voltage of 0.4 kV, in relation to figures 1 ... 4, which represents :

- fig. 1, the single-wire diagram of the transformer station, of the distribution network and 60 of network connection, of a single-phase consumer;

- fig.2, the scheme for connection to the air distribution network, of several single-phase consumers;

- fig. 3, the connection diagram to the air distribution network of a three-phase consumer; 65

- Fig. 4, diagram of connection to the distribution network, of the single and three-phase consumers from an urban area.

The power supply of the distribution network, according to fig.1, is the transformer of the transformer station 1, made with a transformation ratio corresponding to the new voltage of the distribution network, which supplies in three-phase system, through 70 box or distribution panel 2, the electrical network represented by the phase 3 and the null 4 conductors.

The electricity supply to the consumers, according to the invention, is made according to the structure of the distribution network, air or cable and the type of consumers, single or three-phase. 75

The supply of a single-phase consumer or a group of single-phase consumers, from the air distribution network, is carried out according to Figs. 1 and 2, by means of a single-phase transformer, of low power 5, connected to the distribution network, through the fuse box G, and on the side of the secondary winding, the single-phase connection 7 is connected, which supplies the consumer or consumers 8 to 8o the operating voltage of 230 V.

The grounding installation 9 is carried out, jointly or separately, with the assurance of touch and pitch voltages, according to the norms, and 10 represents an intermediate pillar for the execution of individual connections to consumers.

The power supply of a three-phase consumer or an extended group of 85 single-phase consumers (fig.3), from an air distribution network 3 and 4, operating at a voltage higher than 0.4 kV, is performed using the same types of single-phase transformers in three-phase mounting or of a three-phase transformer

5, which have a nominal secondary voltage of 0.4 kV. The three-phase connection 7 supplies power

RO 116141 Bl consumer's general cleavage 8 at the voltage of 0.4 kV, the neutral of the coils of 0.4 kV is connected to the grounding of the network and the consumer 9.

In Fig. 4, an example of the supply of electricity from the cable distribution network 3, of single or three-phase consumers in an urban area is given. The three-phase transformers 5 given as an example in the figure are connected to the electrical distribution network in the cable, through the general wires 6, and through the column 7, the main wire 8 is connected to the operating voltage of 0.4 kV, which allows the power supply of consumers, household subscribers from a block of flats, shops, schools, etc.

The construction of new distribution networks or the transfer of existing 0.4 kV to a higher operating voltage can be achieved by maintaining the current structure for both the transformer stations, as well as for the overhead power lines or 0.4 kV cable.

The insulation level of low voltage insulators, TYIR twisted conductors in the construction of overhead power lines and ACYA (B) Y type cables in the construction of underground power lines, corresponds to a maximum service voltage of 1 kV, so these elements can be used. at voltages higher than that existing in the current distribution networks. Also, the technologies for the execution of the connections, columns, distribution boxes, etc., do not undergo changes, by using a voltage higher than the current of 0,4 kV, in the operation of the electrical distribution networks.

Claims (1)

Method of supplying electricity to low-voltage consumers, characterized by the fact that the operation of the distribution networks operating of 0.4 kV at a higher voltage, up to the limit of 1 kV that characterizes the maximum level of low voltage, is used. to a power transformer (1) with a transformation ratio corresponding to the new voltage of the distribution network, with the preservation of the constructive elements of the transformer station and of the low voltage electrical network, distribution box (2), phase conductors (3) and null (4), supplies the single-phase consumers to the 230 V operating voltage via a single-phase transformer (5) and the three-phase consumers to the 400 V operating voltage through a group of single-phase transformers in three-phase mounting or a three-phase transformer .