Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining a reference phase signal that is synchronized with an alternating current (AC) phase of a multi-phase electrical power distribution system. The apparatus obtains output signals from sensors, each output signal representative of an electromagnetic emission detected by a respective sensor. The apparatus identifies, based on comparing respective phases of the output signals to the reference phase signal, a particular AC phase of the multi-phase electrical power distribution system associated with a source of the emissions. The apparatus provides an indication of the particular AC phase to a user.

Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining a reference phase signal that is synchronized with an alternating current (AC) phase of a multi-phase electrical power distribution system. The apparatus obtains output signals from sensors, each output signal representative of an electromagnetic emission detected by a respective sensor. The apparatus identifies, based on comparing respective phases of the output signals to the reference phase signal, a particular AC phase of the multi-phase electrical power distribution system associated with a source of the emissions. The apparatus provides an indication of the particular AC phase to a user.

Disclosed is a device for detecting a phase loss in an output current in an inverter. The device includes: an output current detection unit for detecting two phases output currents from two signals output from two shunt-resistors connected to two phases legs respectively; an output current calculation unit for calculating an output current of one remaining phase using the detected two phases output currents; and an output phase loss detection unit configured for detecting an output phase loss when the calculated output current is within a current band corresponding to the output phase loss or when the calculated output current has a magnitude equal to and a sign opposite to one of the detected two phases output currents.

Disclosed is a device for detecting a phase loss in an output current in an inverter. The device includes: an output current detection unit for detecting two phases output currents from two signals output from two shunt-resistors connected to two phases legs respectively; an output current calculation unit for calculating an output current of one remaining phase using the detected two phases output currents; and an output phase loss detection unit configured for detecting an output phase loss when the calculated output current is within a current band corresponding to the output phase loss or when the calculated output current has a magnitude equal to and a sign opposite to one of the detected two phases output currents.

Embodiments of the present invention provide a method and system for timing related tasks in IoT systems, for example, in relation to synchronisation of clocks and timestamping. It is desirable that the method and system is able to withstand external tampering in a manner which does not jeopardise the accuracy and integrity of time related tasks in the IoT systems.

Embodiments of the present invention provide a method and system for timing related tasks in IoT systems, for example, in relation to synchronisation of clocks and timestamping. It is desirable that the method and system is able to withstand external tampering in a manner which does not jeopardise the accuracy and integrity of time related tasks in the IoT systems.

Systems and methods can be used in connection with a circuit multi-tester including phase rotation-measurement circuitry. A power-testing device comprising a plug and an enclosure with circuitry can be used to display various power characteristics of a receptacle. The plug of the power-testing device can be received into a compatible power receptacle. The reception of the plug into the receptacle can allow for power communication from a power source supplying power to the power receptacle and the power-testing device for power measurement purposes. The power-testing device can include an enclosure with circuitry that can measure phase rotation information and can detect the presence of power on power lines of the receptacle. Based on the detected presence of power and phase rotation information, the power-testing device can output a visual indicator to the technician that represents the presence of the power and phase rotation orientation.

Systems and methods can be used in connection with a circuit multi-tester including phase rotation-measurement circuitry. A power-testing device comprising a plug and an enclosure with circuitry can be used to display various power characteristics of a receptacle. The plug of the power-testing device can be received into a compatible power receptacle. The reception of the plug into the receptacle can allow for power communication from a power source supplying power to the power receptacle and the power-testing device for power measurement purposes. The power-testing device can include an enclosure with circuitry that can measure phase rotation information and can detect the presence of power on power lines of the receptacle. Based on the detected presence of power and phase rotation information, the power-testing device can output a visual indicator to the technician that represents the presence of the power and phase rotation orientation.

A method and system for detecting and locating a single-phase ground fault on a low current grounded power-distribution network, comprising: respectively testing and picking up the voltage signals and current signals at multiple positions on each phase feeder (61), and determining the corresponding transient voltage signals and transient current signals according to the extraction of the voltage signals and the current signals (62); when the change in the transient voltage signals and the transient current signals exceeds a preset threshold (63), synchronously picking up the voltage signals and current signals at multiple positions on a three-phase feeder (64); calculating corresponding zero-sequence voltages and zero-sequence currents according to the voltage signals and current signals synchronously picked up at multiple positions on the three-phase feeder (65), and then extracting the steady-state signal and transient signal of the zero-sequence voltage and zero-sequence current at each position on the three-phase feeder (66); and determining a specific fault location on a faulty line according to the steady-state signal and the transient signal (67). The method effectively detects and displays a single-phase ground fault on a low current grounded power-distribution network.

A method and system for detecting and locating a single-phase ground fault on a low current grounded power-distribution network, comprising: respectively testing and picking up the voltage signals and current signals at multiple positions on each phase feeder (61), and determining the corresponding transient voltage signals and transient current signals according to the extraction of the voltage signals and the current signals (62); when the change in the transient voltage signals and the transient current signals exceeds a preset threshold (63), synchronously picking up the voltage signals and current signals at multiple positions on a three-phase feeder (64); calculating corresponding zero-sequence voltages and zero-sequence currents according to the voltage signals and current signals synchronously picked up at multiple positions on the three-phase feeder (65), and then extracting the steady-state signal and transient signal of the zero-sequence voltage and zero-sequence current at each position on the three-phase feeder (66); and determining a specific fault location on a faulty line according to the steady-state signal and the transient signal (67). The method effectively detects and displays a single-phase ground fault on a low current grounded power-distribution network.