Compact outdoor transformer substations in concrete shells from 25 to 2500 kVA for a voltage of up to 10 kV

Parameter name	Parameter value
Power transformer capacity	25; 40; 63; 100; 160; 250; 400	630; 1000	1600	2500
Nominal voltage on HV side, kV	6; 10
Highest operating voltage, kV	7,2; 12
Nominal voltage on LV side, kV	0,23; 0,4; 0,42; 0,69
Short-time withstand current during 1 seconds on HV side, kA	12,5; 16; 20
Short-time withstand current during 1 second on LV side, kA	10	20	30	40
Peak withstand current on the HV side, kA	51
Peak withstand current on the LV side, kA	25	50	70	100
Insulation level according to GOST 1516.1:
- with oil transformer - with dry type transformer and with non-combustible liquid dielectrics	Standard insulation Lightweight insulation

Insulation strength of main and auxiliary circuits on the HVD side complies with the requirements of GOST 1516.1.

Parameters and characteristics of CTS enclosures are determined by the customer and the manufacturer.

CTS is operated and has the following parameters of resistance to external environmental factor.

Nominal values of climatic factors of external environment according to GOST 15150 and GOST 15543.1, whereby:

• altitude above sea level shall not exceed 1000 m;
• explosion- and flame-proof environment, containing no conductive and abrasive dust, containing no conductive or chemically active gases, vapors and precipitation destroying insulation and metals (the  I and II type of atmosphere according to GOST 15150);
• ambient air temperature for  CTS - from minus 40 to +40 °C;
• relative humidity of ambient air is up to 80 %.

The design of the CTS enclosure complies with CП 20.13330.2011 and withstands:

• wind pressure shall not be less than 0,3 kPa;
• weight of snow cover on 1 m² of horizontal roof surface shall not be less than 3,2 kPa with a reliability factor of 1,0;
• equally distributed slab loading shall not be less than 2,0 kPa.

Enclosure designs provide protection of internal premises from precipitation intensity up to 3 mm/min.

At the customer's request, it is possible to manufacture a construction block-box with seismic resistance up to 9 points according to СП 14.13330.2011. In this case, the equipment used to complete CTS shall comply with the requirements for seismic resistance specified in the project documentation.

Class of structural fire hazard C0 according to СП 112.13330.2012.

Class of functional fire safety Ф.5.1 according to СП 112.13330.2012.

Design reliability factor is 0.9 for IV class of buildings and structures in accordance with the “Rules of taking into account the degree of responsibility of buildings and structures in the design of structures”.

CTS are not designed for operation in mobile, mine and other installations.

CTS provide:

• performance of the installed high-voltage equipment;
• protection, automation and control of high-voltage equipment, supply and output connections;
• distance control and monitoring of high-voltage equipment;
• performance of the installed LVSD
• protection, automation and control of LVSD, supply and output connections;
• distance control and monitoring of LVSD;
• functioning of supervisory, safety and dispatch connection systems;
• compatibility of supervisory data transmission protocols in accordance with the recommendations of ГОСТ Р МЭК 60870-5-101, ГОСТ Р МЭК 60870-5-104.

The requirements of compatibility of design solutions are ensured by the use of commercially available equipment with standard and unified connection and fastening units, which allows for quick configuration, installation, adjustment and commissioning of CTS.

High-voltage cells of the identical type have the same overall and installation dimensions.

The withdrawable elements (if any) of cells of the identical type are interchangeable.

The design of the LVSD ensures interchangeability of identical withdrawable devices without additional adjustment.

CTS fulfill the requirements for reliability and durability in accordance with GOST 20.39.312.

The operating mode of CTS is twenty-four hours a day. All cabinets are permanently under voltage.

The probability of failure-free operation (for CTS power transformers) for the operating time of 8800 hours shall not be less than 0,995.

Average MTBF shall not be less than 18000 hours.

Average recovery time with a set of spare units is no more than 5 hours.

Installed service life of CTS shall not be less than 25 years (provided that the equipment is maintained or replaced in accordance with the operating instructions for CTS and their components).

The LVSD cabinets shall be capable of withstanding:

• over 1000 door openings and closings;
• the number of switching operations - shutdowns, as well as the number of switching operations from the repair position to the operating one, and from the operating position to the repair one (for LVSD with withdrawable devices) as specified by the relevant standards for switching devices.

Maintenance of the installed equipment and its repair is performed using a set of spare parts from its composition.

CTS block-boxes fulfill the requirements of GOST 22853 applicable to permanently installed facilities.

Reliability of the block-box construction complies with the requirements of СП 20.13330.2011.

The concrete enclosure of the CTS building consists of an ABB and, at the customer's request, an UBC.

Dimensions of ABB и UBC

External dimensions of ABB, mm:
- width	2500, 3000*
- length	5000, 5500, 6000, 6500, 7000, 7500 (only with width 2500)
- height	2570, 2870*, 3070*
External dimensions of UBC, mm
- width	2500, 3000
- length	5000, 5500, 6000, 6500, 7000, 7500 (only with width 2500)
- height	1520 (internal 1400), 1820 (internal 1700)
* - size (width x height) 3000 x 2870 mm has 1 degree of oversize, 3000 x 3070 mm has 2 degrees of oversize for loading on railway transport.

The ABB is a concrete structure with a monolithic slab and walls.

The UBC is a concrete structure of rectangular shape.

The concrete enclosure is made of high-strength concrete. The concrete compression class is B35 (450 kg/cm²). Concrete frost resistance grade is F300.

The design of the CTS in terms of mechanical strength ensures normal operating and transportation conditions without any residual deformation or damage that would prevent normal operation of the CTS.

All ferrous metal parts have a protective coating against corrosion.

CTS parts have a light gray lacquer coating. At the customer's request it is allowed to paint separate assemblies (doors, decorative elements) in other colors and apply distinctive marks in accordance with the customer's standards. The quality of painted surfaces should not be lower than IV class of coatings according to GOST 9.032.

The design of CTS provides the possibility of connection:

• overhead lines;
• cable lines;
• both cable and overhead lines.

CTS, performed with overhead bushings, are equipped with overvoltage suppressors and have a version of bushings of category A or B according to GOST 9920.

CTS are delivered fully assembled or transport units, prepared for assembly at the site of installation without disassembly of switching devices, check the reliability of bolted connections and accuracy of internal connections. The design of the component parts of CTS (transportation units) ensures their matchability.

Doors in CTS are hinged at least 95º and have locks and handles. The handles can be removable or combined with a key or latch. Canopies are provided over the doors.

CTS transportation units and cabinet sections have structural elements for lifting and moving during installation. The slinging points are indicated on the transportation blocks.

The design of the CTS provides for installation on a level surface, as well as attachment to the ABB by welding to embedded parts.

Cable bushings are unified and provide the possibility of free passage through the enclosing structures of the block-box and the connection of external cable lines with ensuring the tightness of the bushing.

The design of CTS can be made in two variants:

• single-module CTS, which is a concrete structure with equipment and power transformer placed inside;
• multi-module CTS , which is a concrete structure of two or more block-modules, with equipment and power transformers placed inside. Modules should be installed closely together. The connection between the modules on the HV and LV sides is performed by cable.

 CTS is divided into power transformer compartment, high-voltage devices compartment (HVD) and low-voltage switchgear devices compartment (LVSD). The compartments are separated by a partition made of non-combustible materials with fire resistance in accordance with the Electrical Installation Regulations.

The ABB CTS has doors for maintenance and installation of power transformer compartments, HVD and LVSD, and openings in the slab are provided for:

• cable in and out;
• transformer oil collection;
• access of service personnel to the UBC.

CTS are supplied with installed power transformers.

The design of the CTS provides the possibility of replacing the power transformer without dismantling the LVSD and the CTS building structures. It has a built-in or attached structural element for installation and removal of the power transformer.

The height of the CTS B room shall not be less than the height of the high-voltage cells, counting from busbar bushings, jumpers or external parts of cabinets, plus 0.8 m to the ceiling.

A lower premises height is allowed if it ensures the convenience and safety of replacement, repair and adjustment of high-voltage equipment, busbar bushings and jumpers.

If there is an overhead entry, the distance from the lowest point of the entry wire to the lowest point of the building foundation shall be at least 4,5 meters.

CTS have in accordance with clause 4.2.94 of the Electrical Installation Regulations:

• in the case of the length of the CTS building up to 7 m is one exit;
• in the case of the length of the CTS  building from 7 to 60 m are two exits at its ends, it is allowed to make exits at a distance of up to 7 m to its ends.

Exits can be made outside, to the stair shaft, or to another production premises of category G or D, as well as to other compartments of  CTS separated from this fire door of II degree of fire resistance.

Doors from the compartments of the CTS shall open in the direction of other rooms or to the outside and shall have self-latching locks that can be opened without a key from the inside. This requirement does not apply to CTS of urban and rural networks with voltage of 10 kV and below.

The slab of the oil-filled power transformer compartment has openings for draining transformer oil into oil receivers, oil inlets and oil collectors in accordance with the requirements of the Electrical Installation Regulations. The volume of oil receiver is designed for simultaneous reception of 100% of the volume of oil poured into the transformer. The oil collectors are of closed type. Oil receivers, oil drains and oil collectors are removed and transported separately during transportation. The slab of the oil transformer compartment has a 2% slope towards the oil receiver.

The construction of the block-box excludes the possibility of free penetration inside through walls, doors, slab, roof and is made of the following structural elements:

• concrete enclosure with monolithic slab and walls, providing stiffness of the block box;
• the main and auxiliary equipment can be installed and wired using embedded parts;
• door units with locking devices;
• cable ducts providing separate wiring of power and signal circuits in accordance with the Electrical Installation Regulations;
• cable glands providing hermetic entry of power and signal cable circuits into cable ducts of premises.

The design of the CTS block box provides:

• preservation of specified thermophysical parameters of premises according to СП 60.13330.2012;
• unhindered access of personnel and repair facilities to the installed equipment, parts and units requiring maintenance and repair, as well as the safe conduct of repair work;
• the necessary processability during manufacturing and assembly at the factory, transportation, installation and operation;
• minimum weight of building structures based on the use of new efficient materials;
• optimal reliability and aesthetics of building structures.