Abstract: A method of monitoring variations is carried out within an electrical energy meter containing means therein for metering a quantity of electrical energy generated by a supplier and transferred via a power supply line to a load. The method includes a first step of sensing a line voltage transferred via the power supply line to the load during the energy measurement time interval. The method also includes the step of detecting a variation in a magnitude of the sensed line voltage relative to an acceptable voltage level, wherein the variation exceeds a first variation threshold. The method then includes the step of capturing a first waveform of the sensed line voltage corresponding to the time when the variation is detected.

Abstract: A revenue accuracy meter and a method are provided for measuring the amount and quality of power received by a power customer across electrical power lines. The revenue accuracy meter preferably has a variation determiner for determining undesired variations in an electrical signal representative of power received by the power customer during a plurality of predetermined time periods. A power usage measurer is coupled in electrical communication with the variation determiner for measuring the power usage of a customer responsive to an electrical signal representative of a customer load. The meter further has a communications interface coupled in electrical communication with the variation determiner and the power usage measurer for communication signals representative of the power variations and the power usage.

Abstract: A method and apparatus for evaluating the performance of a device, such as a quadrature encoder, which generates at least two electrical wave train signals, each varying between first and second states and the two normally being out of phase one with the other. In the invention, four types of change of phase relation between the signals are distinguished from a succession of changes, the interval required for each type of phase change is timed and recorded, and a predetermined plurality of sets of records are accumulated. The mean time interval for a change of phase relation between the two wave train signals is computed from the accumulated plurality of sets of records and compared with the accumulated sets of records of timed intervals for determining the one type of phase change for which the difference from the mean time interval is the greatest.