An enclosed busbar is a busbar system composed of a metal plate as a protective shell, conductive bars, insulating materials, and related accessories. It includes phase-separated enclosed busbars, common-box enclosed busbars, and cable busbars, widely used in power plants, substations, and industrial and civil power lines.

Composition of enclosed busbars: mainly composed of three parts: busbar conductors, supporting insulators, and protective shielding shells. Both the conductors and the shell adopt an aluminum tube structure. In addition, the enclosed busbar uses a slightly positive pressure device to prevent dew condensation and moisture on the insulators, improving the safety and reliability of operation.

What are the characteristics of enclosed busbars? Let's take a look together.

The conductors and shells of phase-separated enclosed busbars are welded from rolled aluminum plates and have the following characteristics::

1. Reduce grounding faults, avoid interphase short circuits, and isolate phase-closed busbars. Due to the shell protection, external moisture, dust, and grounding faults caused by external objects can be eliminated. Phase closure can also be used to prevent interphase short circuits.

2. Eliminate steel structures - the phase-separated enclosed busbar uses a shell shield to solve the problem of steel structure induction.

3. Reduce interphase short-circuit electromotive force. Due to the dual shielding technology of the eddy current and circulating current on the shell, the short-circuit electromotive force experienced by the interphase conductors is greatly reduced.

4. Improve the safety and reliability of operation. The basin-type insulators in this plant are made of SMC pressing. After the busbar is enclosed, it prevents dew condensation on the insulators. At the same time, hydrogen measurement and temperature measurement devices are used. Their measurement signals can be displayed locally or transmitted to the DCS system to improve the safety and reliability of operation. After the busbar is enclosed, it also creates conditions for using ventilation cooling.

5. Enclosed busbars are mass-produced in factories, with guaranteed quality, small operation and maintenance workload, simple installation, and no need to set up safety nets, simplifying the structure and requirements for civil works.

6. Under the conditions of the same phase, including branch electrical grounding and multi-point grounding, the shell is basically at the same potential grounding method, greatly simplifying the danger of electric shock.

Applications of common-phase enclosed busbars: Common-box enclosed busbars include non-isolated common-box enclosed busbars, isolated common-box enclosed busbars, and AC/DC excitation common-box busbars, widely used in:Current transmission between the lead wires of generators below 100MW and the low-voltage side of main transformers, or between the low-voltage side of plant transformers of 75MW and above units and high-voltage distribution devices. They can also be used in generator AC/DC excitation circuits, power supply lines for substations, or other industrial and civil facilities.

Features: Replace sealing gaskets; conductors use copper-aluminum busbars or grooved aluminum/grooved copper.Compact structure, easy installation, small operation and maintenance workload, and can basically eliminate grounding faults caused by external moisture, dust, and foreign objects. The shell is made of aluminum plate, with good corrosion resistance, and avoids additional eddy current losses caused by steel shells. The shell is electrically interconnected and grounded at multiple points, eliminating the danger of electric shock and eliminating the need for safety nets, simplifying the requirements for civil works. According to user needs, heat-shrinkable tubes can be installed on the busbars, and heaters and breathers can be installed in the box to enhance insulation.