Tyhjiökytkinten

Tyhjiökytkinten is a Finnish term referring to vacuum interrupters. These devices are a type of high-voltage electrical switch designed to interrupt fault currents in power systems. The vacuum interrupter utilizes a vacuum environment to extinguish the electric arc that forms when the contacts separate. This vacuum is crucial because it prevents the arc from sustaining itself, unlike in air or oil, allowing for very fast and efficient interruption of current.

The construction of a vacuum interrupter typically includes a sealed ceramic or glass envelope containing the electrical contacts. The contacts are moved by an actuator mechanism, often a magnetic or spring-driven system, which can operate the switch quickly. When the contacts separate under vacuum, the material vaporized from the contacts during arcing condenses rapidly on the internal surfaces of the envelope. This rapid condensation is key to the extinguishing process, as it quickly restores the insulating properties of the gap between the contacts.

Vacuum interrupters are widely used in medium-voltage switchgear and circuit breakers, typically rated from around 1 kV to 40.5 kV. They are favored for their reliability, long operational life, and minimal maintenance requirements. Their compact size and the absence of flammable or toxic extinguishing media also make them an environmentally friendly choice. Applications include distribution networks, industrial power systems, and railway electrification. The principle of arc extinction in a vacuum is highly effective, leading to minimal contact erosion and thus a high number of switching operations before replacement is needed.