The complete transformer substation is one of the projects ennomotive has received to compete in the ‘Most Innovative Project 2018‘ contest.
The complete transformer substation (CTS) is used to receive, distribute and convert three-phase AC power of a certain frequency in those systems where the neutral of the transformer is dead-earthed on the low voltage side. It is intended for power supply of housing and communal, infrastructure, industrial objects, and also cottage settlements and areas with individual buildings in networks with the isolated neutral on the party of 6(10) kV and the dead-grounded neutral on the party of 0,4 kV.
The standard design consists of the following components:
- Cabinet of high-voltage fuses. This compartment includes high-voltage arresters and fuses, a high-voltage switching device, as well as bushing insulators and a current line.
- Power transformer, which is installed in a separate section. As a rule, the description of the basic standard complete transformer substation is given above. In this article, I would like to focus and pay attention to the metal structure of the substation.
CTS of this design is supplied in the form of module compartments. Each module has the ability to rearrange and add new modules to an existing configuration, which allows you to change the scheme of CTS during operation. CTS has the ability to connect to cable and airlines.
The configuration of the CTS depends on:
- transformer capacity (250-1600 kVA);
- number of transformers;
- configurations of the section of the low voltage (LV) (low voltage switchgear);
- configuration of the high voltage compartment (schemes: deadlock, transit, taking into account the high side of the voltage).
CTS contains a transformer compartment, high and low voltage compartments, which are separated by metal partitions and have separate doors for maintenance. Transformer compartment provides installation in it of a power transformer with both dry and oil insulation of windings with the required power.
For ventilation, as well as cooling installed inside the equipment, the structure has openings and blinds. In some cases, the CTS can be equipped with an axial exhaust fan.
Technical requirements for substations of this type suggest that they can be operated only in such conditions:
- non-explosive environment, which does not contain aggressive and conductive dust, wet vapors;
- the installation site is no more than 1 km above sea level.
The frame of CTS is made by bending sheet blanks into a special metal profile with a thickness of 3 mm, and all the outer walls are made of sheet metal with a thickness of 2 mm. The roof is made of sheet blanks with a thickness of 1.5 mm. In this design, there are no stamped elements, such as blinds on the side walls for air circulation. Coating of all parts is made with powder paints of RAL type. The criteria of service life, moisture resistance, fire safety, and structural strength were applied in the calculation of the substation metal structure.
The configuration of component parts-modules allows the following:
- the implementation of any circuit in 10 kV and 0.4 kV electrical networks.
- an increase in the speed of production due to the unification of modules and their docking with each other.
- the possibility in the future, replacement modules (for network development).
- an improvement in transportation services and in loading and unloading.
- a permanent reserve of CTS components.
- a minimum production time.
- the possibility of delivery by rail or road (maximum width of the transport module 2400 mm) assembled or disassembled, as well as the ability to collect on-site.
- an easy installation, as well as the possibility of additional service of installation supervision.
Of course, it should be noted that the cost of such a design is higher compared to the all-welded construction. Empirically found that the coating of all-welded metal in severe adverse weather conditions (heavy rains, heavy snowfalls) cannot withstand a very long time and the design begins to be covered with rust. The modular design allows sandblasting or shot blasting (if necessary), galvanizing or powder coating of each individual part or individual assembly units, as well as good processing of the welding parts.
A separate feature of this design is that there is no need to keep large areas for storage of frames because each assembly unit can be manufactured and packed separately in a box if necessary and sent to the warehouse, which will not take up much space. An important point in the production of such structures is that you can go to mass production and there is no need to develop a separate solution for different customers each time, so there is a line of already product.
In conclusion, it should be said that the modular design is assembled using riveting nuts and hardware. Riveting nuts provide positioning of Assembly units and help to maintain the order of Assembly of the structure. Such modular substations are already used by companies from Dnepropetrovsk (EDS-Engineering) and Zaporozhye (Electroresurs) in Ukraine. The developed design is my own development and all the technical documentation for the creation of such a modular metal structure is available.
Written by: Maksym Gaievskyi (Design Engineer)
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