Indicator phase sequence Qty 1

Portable phase sequence indicator test set, a military or industrial electrical instrument designed to determine phase rotation and verify correct connection of three-phase power supplies. Housed in a rugged fitted carrying case with integral meter, selector dial and test leads, it was used by electrical engineers and maintenance technicians working on generators, distribution systems and heavy equipment. Such units formed part of standard electrical testing practice before compact digital phase testers. 1960s–1970s.