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: A self-powered current sensor is described. The self-powered current sensor including an electrical signal input configured to receive a current signal. Further, the self-powered current sensor includes a power circuit configured to generate a power voltage from an electrical signal. The self-powered current sensor also includes a variable resistor configured to set a value corresponding to one or more indicators on the electrical sensor and an amplifier coupled with a variable resistor and a power circuit. And, the self-powered current sensor includes an alarm coupled with an amplifier, an alarm configured to activate based on a value set by said variable resistor.

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 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 corresponding to one or more indicators on the electrical sensor, and monitor. The monitor is coupled with the electrical signal input, the alarm, 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. And, 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.

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: A self-powered current sensor is described. The self-powered current sensor including an electrical signal input configured to receive a current signal. Further, the self-powered current sensor includes a power circuit configured to generate a power voltage from an electrical signal. The self-powered current sensor also includes a variable resistor configured to set a value corresponding to one or more indicators on the electrical sensor and an amplifier coupled with a variable resistor and a power circuit. And, the self-powered current sensor includes an alarm coupled with an amplifier, an alarm configured to activate based on a value set by said variable resistor.

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 corresponding to one or more indicators on the electrical sensor, and monitor. The monitor is coupled with the electrical signal input, the alarm, 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. And, 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.

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.

Abstract: A device measures current magnitude in a conductor coupled to an electrical device and generates a signal comprising a series of pulses having a frequency. The frequency of the series of pulses is responsive to the magnitude of current measured. The device comprises a sensor magnetically linked with the conductor connected to the electrical device. The sensor produces an analog signal in response to the presence of a current within the conductor. A signal conditioner is located proximate to the sensor and is electrically coupled to the sensor so as to receive the analog signal. The signal conditioner produces, in response to the analog signal, a first signal representative of a magnitude of the current. A converter receives and converts the first signal into an output signal that comprises a series of pulses having a frequency. The frequency of the series of pulses is responsive to the magnitude of the current. All the sensor, the signal conditioner, and the converter are located in a single unitary package.

Abstract: Disclosed is a watt/watthour meter which is capable of automatically correcting incorrect connections between the apparatus and a multiphase AC system. Each power line of the multiphase system is connected to the watt/watthour meter by means of a voltage input line and a current sensing coil. The apparatus is able to determine whether a given voltage input line is connected to the same power line as a given current sensing coil by determining whether the voltage applied to the given voltage input line has the same phase as the current running through the given current sensing coil. If the current and the voltage are the same, this information is stored, and the given voltage input line may be taken as being connected to the same power line as the given current sensing coil.