Zenith Automatic Transfer Switch Withstand and Closing Ratings Technical Bulletin

This document provides detailed information on the withstand and closing ratings (WCR) of ABB Zenith automatic transfer switches, explaining their compliance with UL 1008 standards and NFPA 110 requirements. It covers testing procedures, rating categories (including time-based and specific breaker ratings), and the importance of matching switch ratings to system fault currents to ensure safety and reliability.