A system to measure electrical energy of current in a secondary electrical conductor connected to a primary electrical conductor, the primary and secondary conductors having substantially same voltage. The system includes a primary module including an emitter and a unit for measuring voltage of the primary conductor, at least one secondary module including a receiver, an intensity sensor of current in the secondary conductor, and a unit for calculating energy of the current. The primary module compresses the measured voltage value and emits, to each secondary module, a first message containing the compressed measured voltage value. A time synchronization mechanism performs time synchronization of each intensity sensor with the voltage measuring unit. The calculating unit is connected to the receiver and can calculate energy from the measured voltage and intensity values.

The conventional demand target display device based on time information differing from the information used by electric power companies and electric power consumers causes a divergence regarding their demand values. Therefore, a demand target display device with a dual-purpose scale, which acquires AC signals based on the AC waveform of AC power from a power supply line, generates time information based on the acquired AC signals, transmits the generated time information via radio waves within a housing, receives the transmitted time information via radio waves within the housing, indicates the time on the dual-purpose scale based on the received information, acquires electrical energy consumption within a segment for a given target demand value including the current time, and indicates the relationship between the acquired electrical energy consumption within a segment recorded and a target demand value set for such segment, is proposed.

The conventional demand target display device based on time information differing from the information used by electric power companies and electric power consumers causes a divergence regarding their demand values. Therefore, a demand target display device with a dual-purpose scale, which acquires AC signals based on the AC waveform of AC power from a power supply line, generates time information based on the acquired AC signals, transmits the generated time information via radio waves within a housing, receives the transmitted time information via radio waves within the housing, indicates the time on the dual-purpose scale based on the received information, acquires electrical energy consumption within a segment for a given target demand value including the current time, and indicates the relationship between the acquired electrical energy consumption within a segment recorded and a target demand value set for such segment, is proposed.

A secure detachable utility monitoring device is disclosed, to be appended to a utility metering apparatus for controlling at least one utility usage consumption. A detachable metering monitoring device of at least one embodiment includes: a usage reading interface to acquire a utility consumption value metered by the utility meter; a first memory to store at least a unique identifier ID and a personal key, both pertaining to the device; a crypto processor to generate a cryptogram from information data comprising at least the utility consumption value, the cryptogram being encrypted with the personal key; a message generator to generate an information message including at least the cryptogram and the unique identifier ID; and a communication network interface including a sending unit to send the information message to a remote management center.