Vacuum interrupter for low voltage circuit breaker

Vacuum interrupter, also known as the vacuum switch tube, is the core component of the medium-high voltage power switch. The main function of vacuum interrupter is to make the medium and high voltage circuit cut off the power supply of the vacuum arc extinguishing chamber of ceramic shell through the excellent insulation of the vacuum inside the tube, which can quickly extinguish the arc and suppress the current, so as to avoid accidents and accidents.
A vacuum interrupter uses a high vacuum to extinguish the arc between a pair of contacts. As the contacts move apart, current flows through a smaller area. There is a sharp increase in resistance between the contacts, and the temperature at the contact surface increases rapidly until the occurrence of electrode-metal evaporation. At the same time, the electric field is very high across the small contact gap. The breakdown of the gap produces a vacuum arc. As the alternating current is forced to pass through zero thanks to the arc resistance, and the gap between the fixed and moving contacts widens, the conductive plasma produced by the arc moves away from the gap and becomes non-conductive. The current is interrupted.

AMF and RMF contacts have spiral (or radial) slots cut into their faces. The shape of the contacts produces magnetic forces which move the arc spot over the surface of the contacts, so the arc does not remain in one place for very long. The arc is evenly distributed over the contact surface to maintain a low arc voltage and to reduce contact erosion.
After the surfaces have been finished and cleaned by electroplating and an optical inspection of the surface consistency of all single parts has been performed , the interrupter is assembled. High-vacuum solder is applied at the joints of the components, the parts are aligned, and the interrupters are fixed. As cleanliness during assembly is especially important, all operations are done under air-conditioned clean-room conditions. In this way the manufacturer can guarantee a constantly high quality of the interrupters and maximum possible ratings up to 100 kA according to IEC/IEEE 62271-37-013.