The failure to automatically transfer a building’s electrical load to an emergency generator is a nerve-racking scenario that any facility manager would prefer to avoid. For this reason, automatic transfer switches (ATS) are considered one of the most critical components of an emergency power system. This article discusses the use of “open vs. enclosed” contacts in transfer switches, and also alerts you to a basic transfer switch design feature that may not be in your current specifications, with possible negative consequences for the facility’s owner.
When reviewing emergency power system designs, I am sometimes asked about 4-pole transfer switches. The typical question is “when should I use them?“, followed quickly by “why should I use them?“. Since each project is likely to have special circumstances that make a generic answer impossible, this article focuses instead on providing the basic sources of information that should allow you … Read more