Structure and working principle of high voltage vacuum load switch

The most popular high-voltage load switches on the market are high-voltage vacuum load switches and high-voltage SF6 load switches. This article mainly explains the structure and working principle of the high-voltage vacuum load switch.

High-voltage vacuum load switches are now widely used as arc-extinguishing devices, mainly because they utilize the vacuum interrupter chamber inside the product to interrupt large currents and perform frequent operations.

The main reason for this is that the volume of the arc-extinguishing chamber inside the high-voltage vacuum load switch is relatively small compared to some vacuum circuit breakers, because its internal structure is relatively simple and the pipe diameter is smaller than that of previous arc-extinguishing chambers. The vacuum arc-extinguishing chamber inside the product is mainly fixed on the isolating switch, and the vacuum break and the isolating break are connected in series. During operation, the arc-extinguishing operation is completed by the vacuum arc-extinguishing chamber, while the isolating port mainly undertakes the insulation performance.

During operation, when a high-voltage vacuum load switch closes, the isolating switch and the vacuum interrupter close sequentially. When opening, the vacuum interrupter disconnects first, and then the isolating switch, in the open state, moves to the grounding position via the reversing device.

Currently, the main types of structures on the market that match the internal arc-extinguishing break and isolation break of a switch are as follows:

1. Linkage Structure

This type of high-voltage vacuum load switch mainly separates the arc extinguishing and insulation functions during interruption, and uses an isolating blade to undertake the insulation function.

The main structure is shown in the figure above. The special transmission mechanism designed with new technology allows for simultaneous control of the vacuum interrupter and the series-connected isolating blades with a single operating handle, ensuring normal operation of both ports.

Furthermore, to reduce the overall height of the load switch and facilitate subsequent installation, the vacuum interrupter (2) is fixed on the isolating switch (1). Subsequently, the main shaft (4) can be used to operate the isolating operating shaft (3) and the vacuum interrupter (5). During the closing process, the operating shaft first drives the isolating switch to close, and then, under the action of the spring, the vacuum interrupter will also close accordingly. During the opening process, under the action of the spring, the vacuum interrupter will first quickly open, and then the isolating switch will then separate.

2. Interlocking structure

This type of high-voltage vacuum load switch uses mechanical interlocking protection for the two major functional units, the vacuum interrupter and the isolating blade, enabling the equipment to operate according to normal procedures.

The overall structure is as shown in the figure above, consisting of a disconnecting switch (1), a vacuum interrupter (2), a spring mechanism (3), and a grounding switch (4). The vacuum interrupter is controlled by the spring mechanism. In this structure, the vacuum interrupter can not only perform closing and opening operations for various currents, but also provide insulation.

In interlocked load switches, the disconnecting switch and grounding switch are operated using the same handle. The disconnecting switch is typically only opened during vacuum switch maintenance. This type of equipment is also equipped with two operating handles, allowing for both manual and electric operation. This type of high-voltage vacuum load switch is widely used in combined electrical appliances because it effectively reduces the height of the appliance, making it very convenient and simple to use.