Abstract: An intelligent electronic device (IED) includes a base module having a power monitoring circuit operative to monitor a parameter of a portion of a power distribution system and generate an analog signal representative thereof. The base module also includes a processor coupled with the power monitoring circuit, the processor having an analog to digital converter operative to convert the analog signal to a digital signal representative thereof. The processor operates to implement a first power management functionality and generate first power management data. At least one of a display and a communications interface couple with the processor and communicate the first power management data external to the IED. A first interface couples with the processor and the communications interface. The first interface operates to receive a first external function module.

Abstract: A time synchronization device and method is provided for synchronizing an internal clock of the power monitor. The internal clock may be adjusted to a periodically stable frequency according to a calculated counting error. Also, a time of the internal clock may be synchronized to a universal time, the time of the internal clock advancing at a determined rate. The determined rate may be adjusted if the internal time differs from the universal time plus a processing time.

Abstract: A time synchronization device and method for synchronizing an internal clock of the power monitor to a periodically stable frequency. Cycles of the periodically stable frequency are counted after each elapse of a predetermined time period. The elapse of the predetermined time period defines a present window and a previous window. A counting error and a change in counting error are calculated, wherein the change in counting error is the difference of a counting error calculated for the present window and a counting error calculated for the previous window. The present method detects when a change in counting error is within a predetermined range. When the counting error is within the predetermined range, the internal clock of the power monitor is adjusted to the line frequency according to the counting error calculated for the present window.