Complete switchgears (KRU): types, characteristics, purpose

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

This article will contain information about complete switchgears. Their technical characteristics, types and purpose will be given.

Scope of application

Complete switchgears (KRU) are devices consisting of switchboards, which include:

• devices for starting and controlling electrical receivers;
• safety devices;
• current measuring devices;

As well as other additional components assembled and ready to go.

The main purpose is to receive and further distribute electricity in three-phase networks with an operating frequency of 50 Hz and a voltage of over 1000 V.

Complete switchgears (KRU) are divided into two types: outdoor and indoor installation. For indoor installation, they are placed in buildings or indoors. Such devices are assembled with a busbar system. When used for operating voltages over 35 kV, air insulation is used; in networks of 110 kV, SF6 is used as insulation.

Howas a rule, modern switchgear use high-voltage vacuum circuit breakers as a protection and switching device, but there are more outdated installations in which oil circuit breakers are installed.

KRU RN 6 distribution cabinets are made for outdoor installation and are divided into two types according to execution: rolling out, in which all parts and assemblies are fixed on a special shield, and stationary, where all parts and assemblies are installed for a long service life.

External installation

Complete switchgears for outdoor installation must be prepared for installation, so the foundation is laid first. The cells are moved packed before all devices are installed. After that, the trolleys are unpacked and rolled out of the case, in which the switching equipment is installed. Install the cells according to the layout plan. Installation begins with the extreme. After making sure that the cabinet is installed correctly, install the next one. The important thing is that the cells should not be at an angle.

And for the installation of overhead lines on the roof, brackets are installed. It is also necessary to install local lighting near each cell. High-voltage cable lines are fixed to the switchgear terminals in the rear door of the cabinet with the help of terminations. After that, complete outdoor switchgears are ready for operation.

Design

Completeswitchgear (KRU) for a voltage of 6/10 kV must ensure the normal functioning of all elements installed in it. Switchgear outwardly looks like large steel cells, inside which switching, protective and auxiliary devices are mounted. The external cover of the cell is made of steel sheets, this is done to increase the strength of the structure and protect against short-circuit current damage to other devices located nearby.

Distribution cabinets KRU RN 6 are equipped with special local heating, thanks to which current measuring devices work normally in winter.

Specifications and switching capacity

Complete switchgear (KRU) 10 kV has the following nominal data:

• network operating voltage - 6, 10, 35, 110 kV;
• industrial network operating frequency - 50 Hz;
• working current - 630 A;
• cutoff current - 12, 5, 20, 25, 35, 40 kA;
• isolation - air;
• breaker type – vacuum;
• type of transformer current - TOLK-6;
• type of power transformer – ТМ-25;
• drive type - electric.

Switching stability of the switchgear is determined based on the parameters of the equipment that is built into the device of switches with a drive installed on it. The switchgear, which is installed on the switchgear, must operate normally at rated loads and withstand test cycles at high tripping currents, which are set in the technical specifications of the internaldevices.

Retractable element and degree of protection

The withdrawable element, on which the switching equipment is installed, can be transferred both manually and mechanically. At the same time, such a trolley must pass the path on even surfaces, as it has a rather large mass.

All switchgear cabinets should be easy to use and designed for comfortable installation, repair and replacement of parts. In most switchgear cabinets, when the sliding trolley is being rolled out of the cubicle into the working position, the openings to the fixed disconnecting contacts of the main circuit are locked with special shutters.

Depending on the type of application, there are different types of installations. The switchgear must comply with the requirements of electrical and mechanical strength of the structure, insulation and resistance to aggressive operating conditions. KRU Accommodation Categories:

• U3 - designed to work in rooms with natural air circulation;
• U4 - designed for rooms with artificial climatic conditions.

The design of the switchgear must ensure stability against vibrations that occur during the switching on and off of high-voltage circuit breakers, as well as when the installation is moved. At the same time, all devices must work properly, and relay protection should not work during operation at nominal values.

KRU can be manufactured for different climatic conditions using local heating or cooling.

Operation

During the operation of the switchgear, it is necessary to timely arrange technical inspection and maintenance of the equipment located in the cell, as well as troubleshoot.

The equipment is monitored by electricians on duty or by personnel who operate the installation. According to modern safety requirements, one person is not allowed to work with electrical installations, therefore, at least two people are required when working with switchgear.

Workers who repair the installation must be trained and have a clearance group of at least IV, and must also know about the equipment located in the switchgear and represent the work of individual parts of electrical mechanisms.

Installation with operating voltage up to 35 kV

The BM-4 high voltage switchgear is used to transmit electricity in three-phase current networks with an industrial frequency of 50 Hz and an operating voltage of 35 kV.

KRU cell is a structure sheathed with galvanized steel, the sheets of which are connected by a welded or riveted method. High-voltage circuit breakers, voltage transformers, switching equipment, measuring instruments and a disconnector are installed inside.

Such KRU are designed for two-way service. When installed in small-sized structures, a modified switchgear with one-way service is produced. To maintain the temperature regime in the cells there are blinds. Also, to relieve excess pressure that may appear inin case of emergency operation modes or short circuit currents, break valves are installed on the roof of the cell.

K-63 brand device

KRU brand K-63 is made of a metal case, rigidly fixed on supports, inside which is all the protective, switching and transformer equipment. Complete switchgears of the KRU K-63 type, like the others, are designed for the transmission and distribution of electric current in three-phase networks, with an industrial frequency of 50 Hz and an operating voltage of 6 kV.

KRU K-63 feature is that it can be used as a transformer device. The main switching devices of K-63 are modern high-voltage BB/TEL circuit breakers using electromechanical relays or microprocessor protections.

K-63 cells are designed for indoor installation, and the transformer can be located outdoors. K-63 is assembled with a single busbar system, electricity to which is supplied through high-voltage input cells to the switchgear located on the roof.

Device brand K-594: advantages

Complete switchgear switchgears of grade K-594, like all of the above installations, are used in networks with a voltage of 6-10 kV and an operating frequency of 50 Hz.

As a rule, KRU K-594 are used at transformer substations, power plants, agricultural facilities and railwaytransport. The complete switchgear KRU-594, the price of which depends on the supplier and the region of purchase, is excellent for connecting high-voltage motors and other electrical machines. The main advantages of KRU are:

• all electromechanisms are assembled in one cell and completed at the factory;
• KRU increases the safety of the installation itself, as well as the operating personnel;
• all the most complex elements are installed on a roll-out trolley, which reduces the complexity of equipment maintenance work;
• KRU cells are not bulky, so they significantly save space in the room.

Complete switchgears (KRU) of the K-594 series have technical characteristics that may change in the event of an increase or decrease in the calculated nominal indicators of consumers to which the KRU will be connected.

Conclusion

KRU is a reliable way to connect consumers, as it has high reliability and ease of use, as well as ease of maintenance and repair. They have earned their popularity in the world market as reliable power transmission equipment.