Rectifiers (English: rectifier) is a device for converting AC to DC, power supply device and can be used to detect radio signals. Rectifiers can be performed by vacuum tubes, igniting tubes, solid state Silicon semiconductor diodes, mercury arc to make. Instead, a device for converting DC to AC, then known as the "inverter" (inverter).

Standby UPS only need to charge up the battery, do not need to power a load, so only the charger. In the double conversion UPS in this device to inverter and battery charging, it is called a rectifier/charger.