What is a system designed for critical loads with a second source of supply?

A system designed for critical loads that incorporates a second source of supply is referred to as a duplicate system. This design is essential in critical applications where continuous power supply is vital, such as hospitals or data centers. A duplicate system ensures that if one power source fails or experiences a disruption, the second source can immediately take over without causing an interruption to the load.

This redundancy is key for maintaining operational reliability and safety. In practical applications, a duplicate system might have two generators or two feeds to the same load that work in tandem, ensuring that there's always a backup available. This setup contrasts with other systems, such as radial or looped systems, which do not inherently provide the same level of redundancy for critical loads.