Feedthrough

A "feedthrough capacitor" has a guaranteed minimum value of shunt capacitance[clarify] built in it and is used for bypass purposes in ultra-high-frequency applications.

Instrumentation feedthroughs are used to carry electrical signals (including thermocouples) which are normally low current or voltage.

Another special type is what is commonly known as RF-feedthrough, specifically designed to carry very high frequency RF or microwave electrical signals.

Systems that operate under high vacuum, such as electron microscopes, require electrical connections through the pressure vessel.

There are electrical hermetically sealed feedthroughs for instrumentation, high amperage and voltage, coaxial, thermocouple and fiber optics.