1.Classification of Capacitors
What is vacuum capacitor
Vacuum capacitor is a kind of capacitor using vacuum as media. The plates of the capacitor, which are sealed in a high vacuum ceramic container, are series concentric cylinders made by high conductive oxygen free copper. As the cylinders are shaped by series precise mold, vacuum capacitors have reliable performance and hardly bring out arc and electric corona.
Classification of Vacuum capacitors
Fixed ceramic vacuum capacitors: General fixed ceramic vacuum capacitors, adjustable fixed vacuum ceramic capacitors.
Variable ceramic vacuum capacitors: Convection cooling variable ceramic vacuum capacitors, air cooling variable ceramic vacuum capacitors, water cooling variable ceramic vacuum capacitors
How to define the capacitor
According to Chinese standard, the type of vacuum capacitors should be named after the first letter (capital) of the Chinese pronunciation except capacitor, which is denoted by "C", such as vacuum ceramic capacitor:
By now, adjustable fixed vacuum ceramic capacitors and air cooling variable vacuum ceramic capacitors haven't been made by Chinese company. As Chinese factory is just on beginning of making water cooling vacuum ceramic capacitors, there is not Chinese standard for the name; we just similarly named the capacitors as the original standard.
2.Performance of Vacuum Capacitors
Vacuum capacitors have higher withstanding voltage, smaller volume, lower loss and more reliable performance than capacitors with other media. The particular performance includes the following:
Rated voltage-Due to the excellent insulation of vacuum and the dustproof and moisture-proof performance, vacuum capacitors have high rated voltage when the dimension and the volume are certain. It can achieve hundreds thousands of voltage.
Small loss and high rated current-As vacuum capacitors are made with vacuum medium, low loss ceramic shell and oxygen-free copper plate, it can carry large RF current under general convection cooling, and even the frequency is very high. The carrying RF current can achieve thousands of amperes.
Save space-to a certain capacitance and rated voltage, vacuum capacitors need smallest space.
Wide capacitance range-the ratio of the biggest capacitance to the smallest achieve 150:1, from several pf to thousands of pf, it is an ideal component for wide range tuning.
Self cured ability for excessive voltage-Vacuum capacitor can withstand instantaneous excessive voltage, which will permanently damage other sort of capacitors.
Work in high altitude-vacuum airproof allows vacuum capacitor to work in high altitude without performance decrease.
3.Vacuum Capacitors Notes
Vacuum capacitor through high-temperature welding, is composed by high conductive oxygen free copper, every part is soft. So special package should be prepared for the capacitor to avoid parts deformation during transportation.
Transportation
Handle the vacuum capacitor carefully during the transition, and strong shock is prohibited. User should wear clean gloves when touch the capacitor surface.
Before the package, the vacuum capacitor should be at min capacitance to avoid impact between movable/fixed electrode assembly during the transportation.
Vacuum capacitor can not be horizontally put during the transportation; can not be exposed on the rain and snow.
Storage
Vacuum capacitor should be stored upright in a sealing plastic bag with desiccant.
Vacuum capacitor should be stored in a dry environment and without acid, alkaline and other corrosive gas.
In term of long-term storage, the vacuum capacitors should do the AC high voltage test per 4~6 months, it will help to keep voltage endurance capability.
Before testing the water cooling capacitors, the water in the bellow of capacitor must be clear away. Also the water must be dried out during the storage, since the residual water/moisture will mix with oxygen, also the air would corrode the bellow and affect the life of vacuum capacitor.
4.Quality and Service Commitment
WPVAC guarantees the supplied product is in strict accordance with the contract. The guarantee period of the product is 18 months after delivery (user should do the AC Hi-pot test per 3-6 months during the storage period, and keep the original maintenance record, or WPVAC will not make any promise for the product) or 12 months after installation, whichever is earlier.
