A fault detection circuit includes a micro processing unit configured to output a first pulse width modulation (PWM) signal, a driver electrically coupled to the micro processing unit, and a comparator configured to electrically connect the micro processing unit and the driver. The first PWM signal is configured to drive the driver to output a second PWM signal configured to drive the electrical device. The comparator is configured to compare the second PWM signal with a reference level to output a third PWM signal to the micro processing unit. The third PWM signal contains a number of high level signals and low level signals. The micro processing unit is configured to detect the number of the high level signals and the number of the low level signals during at least one time period to determine a status of an electrical device.

A fault detection circuit includes a micro processing unit configured to output a first pulse width modulation (PWM) signal, a driver electrically coupled to the micro processing unit, and a comparator configured to electrically connect the micro processing unit and the driver. The first PWM signal is configured to drive the driver to output a second PWM signal configured to drive the electrical device. The comparator is configured to compare the second PWM signal with a reference level to output a third PWM signal to the micro processing unit. The third PWM signal contains a number of high level signals and low level signals. The micro processing unit is configured to detect the number of the high level signals and the number of the low level signals during at least one time period to determine a status of an electrical device.

An uninterruptible power supply device provided between a commercial power system and an essential load and supplying AC power to the essential load includes: a power supply part that has an energy storage device and is connected to a power line for supplying power from the commercial power system to the essential load; an open switch for opening/closing the power supply line, the open switch being provided on the power line on the commercial-power-system side of the power supply part; a system abnormality detection part for detecting a system abnormality occurring on the commercial-power-system side of the open switch; and a control part that, when the detected system abnormality is equal to or greater than the tolerance of the essential load or the power supply part against system abnormalities, opens the open switch and supplies AC power from the power supply part to the essential load.

A transmission and distribution system with electric shock protection function includes a transmitting terminal and a receiving terminal. The transmitting terminal includes a switch, a current measurer, a signal generator, and a controller. The receiving terminal includes a filter. The switch is coupled to a first DC power and a transmission line. The current measurer is coupled to the transmission line, and measures a current of the transmission line and provides a current signal. The signal generator provides a disturbance signal to the transmission line. The controller receives the current signal and controls the switch. If the controller determines that the current signal contains the disturbance signal, the controller turns off the switch.

A fault symptom sensing system comprises a slave station including an inference device to infer whether a fault symptom occurs in a power distribution line by inputting waveform data of an electric amount measured in the power distribution line or one or more feature values the waveform data to a trained model received from a master station. The slave station transmits the measured waveform data to the master station w hen the inference device infers that the fault symptom occurs. When the fault symptom actually occurs, the master station's learning device adds the waveform data received from the slave station or ore or more feature values of the waveform data to training data for updating the trained model, and performs additional learning to update the trained model.

A system includes a transformer rectifier unit (TRU) having three inputs, a first AC bus configured to supply power to a first of the three inputs, a second AC bus configured to supply power to a second of the three inputs, and a third AC bus configured to supply power to a third of the three inputs. The system includes a power quality sense device electrically connected to each of the first, second and third AC busses. The system includes an electrically held contactor electrically connected between the TRU and the power quality sense device. The electrically held contactor is configured and adapted to be switched ON or OFF depending on whether the power quality sense device is energized or de-energized.

The invention relates to a novel approach for the protection of electrical circuits from ground faults and parallel and series arc faults in a fully solid-state circuit configuration. Solid-state circuits and methods of use are described that provide the key functions of low-voltage DC power supply, mains voltage and current sensing, fault detection processing and high voltage electronic switching.

The invention relates to a novel approach for the protection of electrical circuits from ground faults and parallel and series arc faults in a fully solid-state circuit configuration. Solid-state circuits and methods of use are described that provide the key functions of low-voltage DC power supply, mains voltage and current sensing, fault detection processing and high voltage electronic switching.

An image forming device that forms an image on a medium, includes: a heater that heats the medium; a control unit that controls the heater; a first path that receives input voltage from an external power supply, converts the input voltage into desired voltage, and supplies the desired voltage to the control unit; a second path that divides the input voltage received by the first path and supplies the input voltage to the heater; a control element that is connected to the second path and controls ON/OFF switching of the heater according to control from the control unit; and a disconnection unit that disconnects the second path depending on condition of the input voltage.

To improve functional security in electric power systems, a fault detector is provided in the electric power system that is connected to the data communication bus and that evaluates streamed values of at least one process parameter. In order to detect an electric fault in the electric power system, the fault detector is arranged to send a fault present indication to the switching element when an electric fault is detected. The fault present indication is sent to and received by the switching element, before the tripping operation of the switching element is triggered upon receipt of the switching command from the automation system, and the switching element triggers the tripping operation of the switching element only when a fault present indication has been received.