Its basic unit is the rectifier, but when it is usually used, a certain number of rectifiers are connected in a certain circuit to form a rectifier stack.
Selenium rectifier components will "age" during use or storage. The so-called aging (or senescence, aging) is the phenomenon that the resistance of the rectifier component changes. After 1000-2000 hours of use, the forward resistance of the selenium rectifier component gradually increases, which is called forward aging, and it is irreversible; during long-term storage, the reverse resistance of the selenium rectifier component will decrease, which is called reverse aging, and it can be restored by "molding". The so-called molding is to gradually increase the reverse voltage on the selenium rectifier component to restore the reverse resistance to the expected value.
Selenium rectifier components are still widely used because they are simpler in manufacturing process than other semiconductor rectifier components, and have a strong overload capacity and automatic recovery rectification after being broken down.