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In power distribution engineering, vacuum circuit breaker, load switch and disconnecting switch are the core three types of equipment. Many project managers or technical novices tend to confuse their functions when selecting models. Through comparative analysis, this article will take you quickly to the difference and matching scheme of these three, and help you optimize the performance of the power system.

一. Snapshot of core functions: What is the difference between the three?

二、 In-depth interpretation: the application position of each switch

 1. Vacuum Circuit Breakers-"The System's Firewall" Vacuum circuit breakers are the first line of defense in the power system. Its core advantage lies in breaking the short-circuit fault current. When a short circuit occurs on the line, it can instantly extinguish the huge arc and protect valuable equipment such as transformers.

Scenario: Substation main transformer cabinet, 10kV power distribution trunk line.

Selection Tip: If your system needs automatic protection and remote monitoring, VCB is the only choice.

2. Load switch-"the backbone of daily control" The load switch is mainly used for on-off under normal working conditions. It can handle rated currents, but not short circuits. Usually we will match the Fuse (LBS Fuse combination), and the Fuse is responsible for short-circuit protection, which not only reduces the cost, but also meets the basic requirements. 

Scenario: Community Ring Network Unit (RMU), factory branch control.

Advantages: Compact structure, high cost performance, suitable for load switching.

3. Disconnector-"Safety Umbrella for Maintenance Workers" The disconnector must not be operated live. Its main function is to create a physical disconnection point visible to the naked eye. Before overhauling the equipment, the disconnecting switch must be pulled off to ensure absolute power failure. 

  Scenario: Power side of circuit breaker or load switch for safety isolation. 

  Taboos: It is strictly forbidden to split and combine with load, otherwise it will produce an arc, which is extremely dangerous!

三. Cabinet collocation and actual combat suggestions 

1.KYN medium voltage cabinet:  vacuum circuit breaker is usually installed. For safety, it will be equipped with a handcart structure, and when the handcart is rolled out, it is equivalent to playing the role of a disconnecting switch. 

2. Ring Network Unit (RMU):  The core is the load switch. In the branch circuit, the combination of LBS + fuse is the current industry standard.

3. Maintenance position:  Before any high-power switch, a disconnecting switch should be connected in series as a mandatory safety specification.

四. Summary 

To protect/operate: Select vacuum circuit breaker. 

To save money/branch control: Select load switch. 

To overhaul safety: Disconnector must be selected.

Zhejiang Liqiang Intelligent Equipment has been deeply involved in the high-voltage power industry for many years, and we provide a full range of medium and high voltage electrical solutions. If you encounter difficulties in project selection, please contact our technical experts to obtain free selection solutions. 

(The purpose of this paper is to provide general reference, please strictly abide by local electric power regulations and design standards for specific projects. )