Solid and split-core current transformers and transducers work like a charm, but their rigidness may not work to the benefit of some circuits. Solid-core CTs are just as they appear—solid slabs that require shutting the power down to enable safe installation. Split-core CTs don’t require this step but can eat up a lot of space in the circuitry.
Fortunately, flexibility and versatility come in the form of a third type of CT: the Rogowski coil. Named after German physicist Walter Rogowski, the coil features the accuracy of a solid-core CT and the ease of installation of a split-core CT, yet works the same way as the two. Inside its colored tubes is a helical ring that responds to the conductor’s electromagnetic field.
Unlike solid and split-cores, Rogowski coils can be adjusted to surround the smallest wires in the system without compromising accuracy. Like a split-core CT, the coil can be installed safely without the need to shut the power down. It’s also ideal for circuits in places where space is a luxury.
Rogowski coils normally come in threes in the market, as well as an energy monitoring module that can support all of them. Like separate monitoring systems, the module stores data over the Internet for convenient access.