Digital Panel Meters FAQQCan I use a combination of one ACA5-20PC ammeter, a 3-position selector switch, and three 5A CTs to monitor current in a 3-phase ac circuit?

Yes, but the selector switch must be a special type referred to as a “make-before-break” switch specifically designed for this type of application. A CT’s secondary output-winding can generate extremely high—and potentially lethal—voltages when the current flowing in its output leads is suddenly interrupted by disconnecting the CT’s output from the ACA5-20PC. Electro Switch Corporation’s www.electroswitch.com part number ‘2409C’ control switch is specifically recommended for this type of application.