The standby UPS is also known as the off-line UPS. It is responsible for providing the primary functions of a USP. It is the one that offers surge protection along with battery backup. The protected equipment will remain connected to the incoming utility power directly. Here the incoming mains supply will power the load without regulation or stabilization. However, the mains supply will continue to remain within the specified input window. Therefore, it offers an inexpensive alternative to the line interactive UPS for protecting the devices and telecom peripherals.