US Patent 7940039 Transformer meter and system for using same

A meter for recording voltage and current on a transformer has current sensors positioned on a housing such that the meter can be mounted to the terminals of the transformer. The device also includes two voltage leads which can be attached to the transformers terminals. An instrumentation module is contained in the housing and is coupled to the current sensors and the voltage leads, the instrumentation module being adapted and configured to record voltage and current measurements from the current sensors and voltage leads. The instrumentation module includes a signal processing module for processing the voltage and current signals to provide other information such as energy and accumulated in-phase current data. Finally, the device includes a communications module coupled to the instrumentation module for communicating the voltage and current measurements and the derived data to a remote user.