Ring distribution board - 3 differences from the disconnector cabinet

The ring distribution board (RDB) is an improved version of the cabinet with a line disconnector. Unlike a traditional disconnector, which serves only to visually break the circuit, the ring distribution board performs the functions of full protection and switching of distribution networks.

This equipment appeared on the market relatively recently, but has already taken an important place in power distribution systems. The main reason for its popularity is the growing number of industrial enterprises and municipal infrastructure facilities that require reliable and functional equipment.

Picture of a ring distribution board

1. What is a ring distribution board

The ring distribution board is an intermediate link between a simple disconnect cabinet and complex distribution devices. It combines switching, protection and isolation functions.

The main difference is the ability to handle load currents. The ring distribution board is equipped with load switches that allow switching off operating currents. Fuses are used to protect against short circuits. This makes the equipment more functional compared to a conventional disconnect cabinet.

The disconnector cabinet performs only the function of isolating a section of the network during repair work. In turn, the ring distribution board provides not only insulation, but also operational control of electricity flows, as well as protection of equipment from emergency conditions.

2. Key differences from the disconnector cabinet

The first difference is functionality. The disconnect cabinet is intended to create a visible circuit break only. The ring distribution board is capable of switching operating currents and disconnecting short circuits.

The second difference is equipment. In the disconnector cabinet, protection is provided only by fuses. The ring distribution board is equipped with load switches, fuses and additional protection devices.

The third difference is the scope. Disconnect cabinets are used primarily on linear branches. The ring distribution board is used at nodes of distribution networks, at substations and industrial facilities.

3. Main Applications

Ring distribution board is used in various sectors of the electrical power industry:

at electrical stations and substations of various voltages;

in power distribution systems of industrial enterprises;

for starting large high-voltage motors;

in urban and agricultural distribution networks;

at renewable energy facilities.

This equipment is successfully used both in harsh climates and in regions with high humidity, which confirms its versatility and adaptability to various operating conditions.

The equipment can be installed both indoors and in special container versions for outdoor installation. This provides flexibility when designing new facilities and upgrading existing ones. Thanks to its wide operating temperature range and resistance to external influences, the ring distribution panel remains a reliable solution for any type of installation, from remote substations to urban distribution networks.

4. Design options: air and gas insulation

There are two main design types of ring distribution board.

The first option uses air insulation. All live parts are connected by copper busbars, and switching is performed by a load switch. This design is characterized by ease of maintenance and availability of repairs. However, it requires more space to accommodate.

The second option is a completely sealed gas-insulated tank. All equipment is placed in a closed volume filled with SF6 gas. Sealed versions are characterized by compact dimensions and high reliability. They are resistant to external influences and are suitable for installation in confined spaces.

5. How to choose the right version

The choice of a specific type of equipment is determined by several factors:

operating conditions and climatic features of the region;

available space for installation;

requirements for reliability and uninterrupted power supply;

budget and operating costs.

In addition, service availability and spare parts availability must be considered, which affects the long-term operational efficiency of the equipment.

The air insulated ring distribution board is preferred for applications where space is available and ease of maintenance is required. Hermetic gas-insulated versions are chosen for urban substations and facilities with high requirements for compactness.

Equipment of both types is successfully used in distribution networks with voltages up to 35 kV. The ring distribution board remains a popular solution for modernization and construction of new power generation facilities.

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