6(10)/0.4 kV compact indoor transformer substations

The composition of the package transformer substations is determined by the customer and design decisions and in the general case consists of a HVN (high voltage device), power transformers (one, two, etc.), low voltage switchgear - a set of cabinets upon request.

In addition, the following are supplied complete: connecting devices on the high voltage side, connecting devices or busbar ducts on the low voltage side, as well as busbar ducts for connecting sections of RUNN busbars (see Fig. 1).

Upon request we can supply: lifting trolleys for removing switches, spare parts and accessories, etc.

A single-transformer CTS consists of an input device on the high voltage side, a power transformer, casings to protect the power transformer terminals, and a switchgear on the low voltage side (see Fig. 2).

A two-transformer CTS has two input devices on the high voltage side (HVN), two power transformers with protective casings and a switchgear on the low voltage side (LVS). In addition, a substation can have up to two emergency inputs (DGS or other emergency power sources).

CTS uses three-phase two-winding power transformers of domestic and foreign production, the design and operation of which is given in the technical description and operating instructions for a specific type of transformer. Upon request, the transformer can be equipped with an autonomous forced ventilation control system integrated into the general substation automated control system.

CTS can have a single-row or double-row arrangement. With a double-row (multi-row) arrangement of a two-transformer package substation, sectional bus bridges are used for electrical connection of sections of a low voltage switchgear (LVSD) (see Fig. 3). Upon request, CTS can be manufactured in other configurations (for example, with a separate transformer).

The components of the CTS, depending on the seismicity of the location area on the MSK-64 scale, are manufactured in the following versions: non-seismic resistant (up to 6 points inclusive), seismic resistant (on request from 6 points to 9 points inclusive).

Parameter name	Parameter value
Power transformer power, kVA	25; 40; 63; 100; 160; 250; 400; 630; 1000; 1250; 1600; 2000; 2500; 3150; 4000
Rated voltage on the HV side, kV	6; 10
Highest operating voltage on the HV side, kV	7,2; 12
Thermal resistance current for 1 s on the HV side, kA	25
Electrodynamic resistance current on the HV side, kA	51
Insulation resistance of input circuits on the HV side, Mohm, not less	100
Rated voltage on the LV side, kV	0,4; 0,69
AC frequency of main circuits, Hz	50±1,25; 60±1,25
Rated voltage of auxiliary circuits, V	24, 110; 220
Electrodynamic resistance current on the LV side, kA	25; 50; 70; 130; 150; 178
Thermal resistance current for 1 s on the LV side, kA	10; 25; 30; 65; 75; 89
Rated current of busbars of a LVSD, kA	0,40; 0,63; 1,00; 1,25; 1,60; 2,00; 2,50; 3200; 4,00, 5,00, 6,30
Rated current of distribution buses of a LVSD, A	630; 1000; 1600; 2000; 3200
Type of grounding system of a LVSD	TN-C; TN-S; TN-C-S
Degree of protection of package transformer substation components	IP21; IP31; IP41; IP54

Low voltage switchgear (LVSD) is designed for receiving and distributing three-phase alternating current electricity with a frequency of 50 Hz, voltage 690/380/220 V, in networks with a solidly grounded neutral, as well as for controlling electrical equipment and protecting it from short circuits and overloads.

The LVSD consists of a set of cabinets for various purposes, in which power switching devices, measuring instruments, control, protection, automation and alarm devices are installed, as well as installation of power and auxiliary circuits.

The switchgear is divided into separately transportable sections of complete factory readiness, prepared for installation at the installation site (see Fig. 4, 5).

Each LVSD cabinet is based on a frame, either welded or prefabricated. The frame is rigid, non-deformable and impact-resistant, with high dynamic resistance, which allows the implementation of LVSD up to 6300 A. Welded frame parts are made of bent steel profiles 2.5-3 mm thick and coated with powder paint. Prefabricated frame parts are made of galvanized steel bent profiles 2.5 mm thick. The profiles of the prefabricated frame are connected with corner clamps, providing a strong and reliable structure. The shell is made of sheet steel coated with powder paint RAL 7035, light grey.

The cabinets in LVSD are separated from each other by metal partitions, which increase service safety and reduce the consequences of short circuits. The cabinet busbars are located in a separate compartment located under the cabinet roof; non-insulated copper busbars are used (or insulated upon request). The LVSD cabinet consists of modular elements and allows the installation of switchgear switchboards of any configuration in stationary and retractable panel designs with various options for separating functional units in accordance with GOST R 51321.1-2000 (IEC 60439-1).

The cable and busbars can be supplied at the top or bottom of the cabinet. Upon request, LVSD cabinets are equipped with gland entries for cables, as well as gland panels on the bottom or top (see Fig. 6).

Operational maintenance of a double-sided cabinet is carried out from the front; access to the busbar and cable assemblies is provided from the rear side of the cabinet. Also, current transformers are installed at the rear to organize protection circuits and electricity metering. With a one-sided LVSD design, maintenance and access is provided only from the facade.

Automatic switches of stationary, plug-in or drawout versions are used as power protective switching equipment in LVSD cabinets. In the case of using stationary switches, disconnectors are additionally installed to ensure a visible break. It is possible to manufacture LVSD with input and sectional load switches and microprocessor protection units. Automatic switches of withdrawable and plug-in types ensure their quick replacement and adjustment without de-energizing the section or cabinet.

To equip LVSD with power switching devices (see Fig. 7), automatic switches of the types UAN, UAS, UCB, UPB (manufactured by JSC CHEAZ), as well as other manufacturers, are used.

LVSD cabinets, according to their functional purpose, can be of the following types: input, sectional, distribution, electricity metering, relay, cable, cabinets with installation of capacitor reactive power compensation, etc. The type and number of cabinets is determined by the customer.

1. Cabinets for input of working (emergency power) and partitioning

Input cabinet - designed for connecting power inputs and transmitting electricity to sections of outgoing lines.

Automatic backup power switch cabinets (ASB) are designed to restore power supply to consumers by automatically connecting a backup power source when the worker is disconnected, as well as returning to the main power supply circuit when the main power source is restored.

The sectional switch cabinet provides sectioning of busbars.

There is a slot in the door of the compartment for the withdrawable circuit breaker, which allows the following operations to be performed when the compartment door is closed:

• control the circuit breaker (using the mechanical switch on and off buttons),
• visually monitor the state of the switch “on-off” and its position “connected-control-disconnected”,
• cock the switch drive using the manual cocking handle,
• set and change the settings of the semiconductor release,
• set the switch to the “control” position and to the “disconnected” position.

The compartment of the input or sectioning switch control panel on the front side houses the equipment determined by the ATS circuit, as well as additional devices for metering electricity and monitoring network parameters. Appropriate control and measuring instruments are installed on the compartment door. If there is a microprocessor relay protection unit in the control panel, it is installed on the cabinet door, with its display displayed on the front side of the door. Also on the door of the control panel there is the following alarm system: circuit breaker status, protection activation and automatic transfer switch. An example of a sectional switch cabinet with separation markings for different bus sections is shown in Fig. 9.

2. Cabinets with installation of capacitor reactive power compensation

 Cabinets with installation of capacitor reactive power compensation can be either separately located or built into the LVSD panel. Protective switches for the installation of capacitor reactive power compensation can be part of the outgoing line cabinet, or directly in the cabinet with the installation of capacitor reactive power compensation (see Fig. 11). Automatic regulation of the parameters of the reactive component of the network is carried out by a Novar type controller with the possibility of integration (on request) into the automated control system of the package transformer substation or at the upper level.

3. Linear cabinets

The low-voltage linear cabinet is designed to connect and protect outgoing lines; can be used with cable cabinets if necessary.

Linear cabinets are equipped with functional power distribution units (PDB) and control units. Distribution blocks are designed to protect cable lines, electric motors and other consumers. Control units are used to control reversible and non-reversible electric motors, valves, process equipment, lighting, etc. It is possible to connect telecommunication circuits, which increases the convenience and safety of the equipment. Upon request, a circuit for other functional purposes can be implemented in the block. Lighting equipment is located on the front panels.

Depending on the type of installation, line cabinets can be manufactured with stationary or withdrawable modules. Cabinets with stationary modules are made on the basis of a prefabricated or welded frame, cabinets with withdrawable modules are manufactured only on the basis of a prefabricated frame made of galvanized profiles.

A cabinet with stationary modules is characterized by a rigid, fixed installation of stationary modules, which are circuit boards with equipment placed on them. Switching devices are installed in stationary, plug-in or withdrawable versions.

The configuration of the stationary module is determined by the adopted form of partitioning. Each block can be located in its own individual cell with controls located on the door (see Fig. 12, 13). When placing the blocks behind a common cabinet door, operational control of the blocks is possible with the door open or remotely (see Fig. 14). To power stationary modules, distribution outlets of copper busbars are installed in the cabinet with stationary modules, to which the terminals of switching devices are connected by wire or copper busbar.

A low-voltage linear modular cabinet with withdrawable modules houses withdrawable modules of various types with stationary circuit breakers installed in them (see Fig. 15). Withdrawable modules (RM), installed in a cabinet with withdrawable modules, provide convenient and safe equipment maintenance. The compactness of the retractable mechanism allows you to install the maximum possible amount of equipment in one module without compromising ease of use. The retractable mechanism ensures ease of movement of the module, and reliable structural elements of the mechanism ensure operation of the product without breakage or jamming. Removable (withdrawable) modules within cabinets with withdrawable modules can be moved to various positions, even if the electrical circuits to which they are connected are energized. The load must be disconnected. All unified modules have special locks that prevent incorrect actions by personnel. The retractable module (RM) can occupy the following fixed positions: attached (working), control (test), disconnected (with blocking from rolling out) and separated (non-working).

The connection of retractable units to vertical power buses and auxiliary circuits is carried out through special adapters. The adapter has plug-in contacts for connecting the power circuits of the retractable unit to the vertical busbars, and also has holes for the output of the wiring harness of auxiliary circuits.

 Examples of cabinets with withdrawable modules for double-sided and single-sided service - see Fig. 16 and 17.

4. Electricity metering cabinets

Metering cabinets (MC) are designed for installation of meters for technical or commercial electricity metering of outgoing lines (complete with sealable test boxes). Control cables are entered into metering cabinets from above or below as required by the customer (see Fig. 18). Upon request, additional equipment can be installed in the MC: loading resistors, interface splitters, backup power devices, etc.

If necessary, meters with test boxes can be installed on the rear doors of the cabinet from the inside, in the area where the corresponding feeder is located.

Automatic transfer of reserve (ATS) can be carried out using various power supply schemes.

Two inputs to a common bus system

In this circuit there are two inputs: 1 main and reserve. Both inputs are connected to one section, to which the load is also connected. In normal mode, only the main input is operated, and in the event of a malfunction of the main input, the ATS control circuit turns off the main input and then power is supplied from the backup input.

Two working inputs with sectioning

This circuit assumes power from two inputs, each of which is connected to a separate section. The connection of two sections is carried out using a sectional switch. In the event of a power loss at one of the inputs, the ATS control circuit sends a signal to turn it on and, thereby, connects the section that has “lost” power to the working input section.

Two working inputs with sectioning + input from diesel power plants

In this circuit, power is provided in the same way as in the “two working inputs with sectioning” circuit. The main difference of the circuit is the presence of a third input from the diesel power station to one of the sections of the LVSD buses. In the event of a power loss at both inputs, the diesel power plant is switched on. The input from the diesel power station is disconnected when voltage appears at one of the inputs of the LVSD bus sections.

All power supply circuits have a blocking for switching on the section switch to the emergency input from the diesel power plant in the event of a short circuit on the low voltage side. Upon request, a guaranteed power source is included in the power supply circuit for control and alarm circuits.

On the front doors of the package transformer substations cabinets there is an LED signaling of the state of switches, protection activation, and fault signaling.

The elemental basis for organizing ATS can be:

• diagram of electromechanical relays;
• programmable intelligent relay type Logo (“Siemens”), Zelio (“Schneider Electric”);
• PLC controller type S7 1200 (“Siemens”) or others;
• microprocessor relay protection unit type BEMP (manufactured by JSC "ChEAZ"), BMRZ (OOO "NTC Mekhanotronika"), etc. (see Fig. 19).

ATS circuits have various designs, differing in the following characteristics:

• by control circuit voltage;
• by time delay at ATS;
• by type of management;
• in terms of the scope of monitoring the characteristics of voltages, currents and other parameters;
• by type of remote control of actuators;
• according to the communication protocol used with the upper control level, etc.

When implementing ATS on microprocessor devices, the necessary software is installed at CHEAZ JSC and supplied as part of the microcontroller.

PTS can be manufactured adapted for operation in automated process control systems and automated control systems, with telemetering, remote control of inputs and linear feeders, constant monitoring of specified parameters and data transmission to the upper level. Also, upon request, temperature control of contact connections in a given volume can be organized (only for busbars, for input switches or for all switching devices, etc.), for an example see Fig. 20.