Abstract: An electronic electricity meter which, in one embodiment, includes a modem board, or unit, coupled to the meter microcomputer and exchanges information between the meter and a central computer is described. Using signals supplied by the meter microcomputer and the central computer, the modem unit microcomputer can determine whether to exchange information between the meter and the central computer and the proper time at which the information should be exchanged. In an exemplary embodiment, the modem unit detects various conditions within the meter and responds by exchanging information with the central computer at a proper, or pre-defined, time. The modem unit has two different basic modes, or states, of operation. These states of operation are sometimes referred to as the call originate mode and the call answer mode. Call originate refers to the mode of the unit when a condition occurs in meter 10 and information is being transmitted to the central computer from the modem unit utilizing a telephone line.

Abstract: An electronic energy meter is described. The meter includes, in one form, voltage and current sensors having their outputs coupled to an analog to digital converter. The digital signals output by the converter are supplied to a digital signal processor (DSP) which outputs digitized metering quantities to a microcomputer. Using the metering quantities supplied by the DSP, the microcomputer performs additional metering calculations and functions. In one aspect, the present invention is directed to a method for determining whether an option board is being used and, if so, controlling meter operations in accordance with the coupled option board.In another aspect, the present invention is directed to a high function option board which, when enabled, operates as a master and the meter microcomputer automatically switches from its normal master mode to slave mode.

Abstract: An electricity meter having a protected enabling scheme for activating meter options and upgrades is presented. The meter has a unique serial number, which includes bit-flags indicating which options have already been enabled, stored in the non-volatile RAM. Each option which is not enabled must be requested and a password verified before it can be utilized. At least one password is stored in a read protected location in the non-volatile RAM. The meter is in communication with a computer, e.g., a desktop or laptop type of computer. The password is generated by processing a secret software key and the unique serial number of the meter with an authentication algorithm. The computer is loaded with an upgrade software program, which includes the authentication algorithm. A hardware key which stores a secret software key is attached to a parallel port of the computer.

Abstract: Line voltage and line current signals are sensed on a power line having at least one conducting path. The sensed line voltages and line currents are converted into a digital signal. A phase-to-neutral voltage signal and phase current signal are computed from the digital signal to thereby define a phase of the power line. An interval of orthogonality is determined from the sensed voltage and current signals, coinciding with passage of an integral number of cycles of a fundamental frequency reference signal which is computed from the computed phase-to-neutral voltage signal. A vector metering quantity is computed for the determined interval of orthogonality from the computed phase-to-neutral voltage signal and the computed phase current signal. The vector metering quantities to be computed may be identified and computed based upon an associated detent. The vector metering quantity is also computed based on an identified circuit topology.