Patent ID: 7999532

Claim:
An apparatus for electronically measuring or distributing electrical energy, said apparatus comprising: at least one analog-to-digital converter connected to phases of an electrical service, said converter configured to obtain digital samples of the voltage component and the current component of said electrical service; a memory for storing reference information for at least one type of electrical service; a microprocessor interfaced with said at least one analog-to-digital converter and said memory; wherein said microprocessor is configured to calculate a voltage phase angle value for the voltage component for at least one phase of said electrical service by use of said digital samples; wherein said microprocessor is configured to use said digital samples to calculate a voltage phase angle value for the voltage component of at least two phases of said electrical service; and wherein said microprocessor is configured to use the voltage phase angle values to determine the phase rotation of said electrical service; wherein said apparatus further includes a display and wherein said apparatus is configured to display with said display a message that is representative of the determined phase rotation; and wherein said apparatus is configured to display a message indicating that the phase rotation of said electrical service cannot be determined if a phase-rotation-warning is generated.