Split-core current transformers designed specifically for Smart Grid applications, characterised by high accuracy and low phase shift. ATO meets IEC 61869-2 requirements for both ratio error and phase displacement — standard current transformers typically satisfy ratio accuracy but fail phase displacement requirements; ATO satisfies both, which is the defining specification for smart grid and IoT energy metering. Covering 5 to 125A with 10mm to 16mm diameter sensing apertures; current or voltage output; most models are self-powered, with the ATO-5-B420-D10/SP4 requiring an external 20–28V DC supply. Mounts directly on the primary conductor via a plastic tie slot with no disconnection required; optional DIN rail adapter; 1m output cable; compact and low-cost.

Applications include hybrid inverters (home energy storage), active power metering, building sub-metering for energy efficiency and cost allocation, power quality monitoring, distributed measurement systems, and condition monitoring of motor loads such as conveyors and pumps in IoT remote energy monitoring networks.