Central Power Supply Systems (CPSS) are a specific type of standby power solution used with emergency and safety-related applications such as lighting, alarms and security systems. A CPSS is used to power emergency systems, mainly for security lighting in public and private buildings, but also for automatic firefighting systems, fume extraction equipment, alarms and carbon. An Uninterruptible Power Supply system provides uninterrupted power supply to critical equipment and devices during power outages. Independent Power Supply Mode 2.