Abstract: A multiphase ground fault circuit interrupter includes a first phase power line input, a second phase power line input, a third phase power line input, a neutral line input, a controller circuit having a relay control output, a first phase latching relay having a first phase switch input coupled to the first phase power line input and a first phase relay control input coupled to the relay control output of the controller circuit, a sensor having a core and a sensor pickup coupled to the controller circuit, and a first phase load wire coupled to a first phase switch output of the first phase latching relay and passed through the core.

Abstract: A multi-phase VFD system with frequency compensated ground fault protection includes a variable frequency drive (VFD) power supply, a motor coupled to the VFD power supply by a plurality of power wires and a relay, an annular magnetic core provided with a sensor winding, where the plurality of power wires extend through the annular magnetic core, an analog signal conditioner, an analog-to-digital (A/D) converter, and a digital processor performing a Fast Fourier Transform (FFT) process on the received digital output of the A/D converter to provide frequency information which is used to develop a frequency equalized transfer function for calculating ground fault current.

Abstract: An electrical sensor is described. The electrical sensor including an electrical signal input configured to receive an electrical signal, an alarm, one or more inputs configured to set a configuration value and at least one display configured to display said configuration value. The monitor is coupled with the electrical signal input, the alarm, the display, and the one or more inputs. Further, the monitor is configured to determine a characteristic of the electrical signal received on the electrical signal input. The monitor is configured to activate the alarm based on the configuration value set by the one or more inputs and the characteristic of the electrical signal. And, the monitor configured to generate at least one display signal based on the configuration value to be used by the at least one display to display the configuration value.

Abstract: A magnetometer that senses low level currents flowing in a conductor or wire includes two cores with excitation windings on each core that are connected in series but which are wound in opposite orientations. A periodic alternating current drives the windings. Since the windings are in series but oppositely wound, the current flowing through the windings will produce equal but opposite flux flows in the two cores. A sensing winding is wound around both cores to provide flux profiles. A digital processor analyzes a quiescent flux profile, which is generated when no sense current is flowing through the dual cores, and distorted flux profiles when sense currents are flowing through the dual cores to measure a sense current flowing through the dual cores.

Abstract: A direct current transducer includes an open-loop Hall-effect sensor, a first ADC coupled to the open-loop Hall-effect sensor, a thermistor, a second ADC coupled to the thermistor, a manually controlled mode-selection device, a digital processor coupled to the first ADC and the second ADC, and digital memory coupled to the digital processor. The manually controlled mode-selection device is operative to develop an operating mode selection digital signal for a plurality of operating modes including a temperature-compensated direct current (DC) transducer mode and a calibration mode.

Abstract: An electrical sensor is described. The electrical sensor including an electrical signal input configured to receive an electrical signal, an alarm, one or more inputs configured to set a configuration value and at least one display configured to display said configuration value. The monitor is coupled with the electrical signal input, the alarm, the display, and the one or more inputs. Further, the monitor is configured to determine a characteristic of the electrical signal received on the electrical signal input. The monitor is configured to activate the alarm based on the configuration value set by the one or more inputs and the characteristic of the electrical signal. And, the monitor configured to generate at least one display signal based on the configuration value to be used by the at least one display to display the configuration value.

Abstract: An apparatus for setting a digital setpoint for a self-powered current sensing switch includes a current transformer, a digital processor and a parallel converter for converting the AC output of the current transformer to a DC power source for the digital processor along a first path and into a digital signal which is input to the digital processor along a second path. The apparatus also includes a manually operated switch coupled to the digital processor and having a calibration mode position, code segments executing on the digital processor to convert the digital signal to a digital setpoint value when the manually operated switch is in the calibration mode position, and non-volatile memory for storing the digital setpoint value.

Abstract: An apparatus for measuring RMS values of burst-fired currents includes a current sensor having a signal output, an analog-to-digital (A/D) converter coupled to the signal output of the current sensor, a digital processor coupled to an output of the A/D converter, and a digital memory coupled to the digital processor. Code segments stored in the digital memory are executable on the digital processor and implement a process of: a) initially sampling the output of the A/D converter; b) determining from the initial sampling a burst-fired current pattern; c) sampling the output of the A/D converter N times within a burst-fired current pattern to provide N samples; and d) calculating an RMS value from the N samples.