Battery backup power is initiated with the Backup UPS device, also called a Standby UPS. Following a blackout, a Backup UPS delivers power for short periods of time. When it detects losses, the transfer switch initiates backup processes. Switchover times occur in milliseconds after failure, with response times varying by standby UPS unit. The switch time is not instantaneous but should not normally interrupt the flow of power to equipment. If a lengthy outage is expected, the battery backup power of the UPS will allow for safe shutdowns, so equipment and data is protected.