Apparatus and method for monitoring power

Abstract

A power monitor, for determining real and imaginary power associated with one or more line signals, samples a plurality of line cycles during an observation window to generate a plurality of voltage-current sample sets for each line cycle. The sampling of the sample sets is timed such that the voltage-current sample sets are taken at different relative time positions. The power monitor stores incoming voltage-current sample data in one memory area and concurrently analyzes sample data already stored in another memory area. Deletion of sample data is not permitted until transient analysis of such data is complete. In another embodiment, the power monitor includes a working data memory area coupled to the sampling circuitry such that the sample sets occurring during each observation window are stored in the working data memory area in interleaved fashion to simulate a single cycle of data. This power monitor further includes a transient data area, coupled to the sampling circuitry, for storing the sample sets occurring during an observation window in a non-interleaved or sequential fashion. Power analysis is conducted on the sample sets in the working data memory area unless a power transient is sensed. Upon sensing a transient, data from the transient data area is provided for analysis.