This white paper describes what a Flex CT is, how it works, and a brief history on its development. Details are given on how to use the Flex CT to get accurate current measurements with PMI’s power quality analyzers. Although the Flex CT is often referred to as a current transformer it is really a Flexible Current Transducer, not a true current transformer. It is however a special type of current transducer that allows for use in areas where conventional current transformers may not easily go. The design of the Flex CT allows it to be wrapped around a conductor, rather than clamped with a rigid CT. The technical name for this type of current transducer is a Rogowski-Chattock coil, named after its inventors. Usually the Rogowski-Chattock coil is referred to as simply a Rogowski coil.

This white paper includes:

• History of the Rogowski coil
• Effect of coil placement on measurement accuracy