White Paper Gallery

UL1008 Transfer Switch Withstand and Closing Ratings

UL1008 specifies robust testing requirements for verifying manufacturer ratings, including Withstand and Closing Ratings. This narrative describes the need for Withstand and Closing Ratings and summarizes key UL1008 tests used to verify them.

Standards and Codes, Transfer Switches

2020 NEC Changes for Backup Power

The National Electrical Code® (NEC®) specifies requirements for safeguarding persons and property from electrical hazards, recently released as the 2020 Edition.

Standards and Codes

Performance Testing for Transfer Switches

This paper summarizes the need for, nature of, and effects seen during switching tests, and discusses how the results benefit end users.

Transfer Switches, How Things Work

Timing Delays for ATS Transition Modes

This paper briefly summarizes common transition modes for Automatic Transfer Switches (ATS), identifies timing delays that are typically available on transfer switches, and describes delays that are specific to certain ATS transition modes.

Transfer Switches, How Things Work

Transferring Motor Loads Between Power Sources

This paper summarizes approaches for avoiding excessive in-rush currents that could trip breakers, damage motors and load equipment, and overload generators when transferring motor loads.

Transfer Switches, How Things Work

Benefits of Custom-Engineered Transfer Switches

The following narrative identifies benefits that custom engineering services can bring to power transfer switches. It also provides examples of custom-engineered features commonly added to power transfer equipment.

Transfer Switches, How Things Work

Connecting Closed Transition Transfer Switches to Utility Services

Closed Transition Transfer Switches (CTTS) transfer loads without interrupting power when both power sources are available and each presents acceptable characteristics. The following narrative provides important application information for this type of switch.

Application Focus, How Things Work, Transfer Switches

Is There a Microgrid in Your Facility’s Future? Part 1

Whether it is power reliability and resilience, increased sustainability, or cost savings, there is tremendous interest in Microgrids for backup power. Part 1 of our series explores the question "What is a Microgrid?"

Application Focus