SQUARE D
SQUARE D Patent applications | ||
Patent application number | Title | Published |
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20100169034 | Apparatus and Method for Measuring Load Current Using a Ground Fault Sensing Transformer - A circuit that includes a single grounded fault sensing transformer coupled to a resonant circuit that produces an output signal used by a microcontroller to determine a load current flowing through at least two conductors passing through the center of the sensing transformer. The microcontroller pings the resonant circuit, causing an impulse disturbance at the output signal, and the microcontroller calculates the inductance component of the resonant circuit based on the frequency of the decaying output signal. The microcontroller calculates the resistive core loss as a function of a known resistance of the resonant circuit, a known capacitance of the resonant circuit, the calculated inductance, and the determined rate of decay of the output signal. The calculated resistive core loss is compared to a table or to a polynomial function that characterizes known resistive core losses with known load currents to determine the load current corresponding to the calculated resistive core loss. | 07-01-2010 |
20100149711 | Circuit Breaker With Bistable Display - A circuit breaker is disclosed that has a bi-stable display that maintains an indication of a fault condition after power is interrupted to the circuit breaker. The circuit breaker has a microcontroller that receives power derived from a line current that passes through the circuit breaker or the line voltage when the circuit breaker is in an on state. The bi-stable display is electrically coupled to and controlled by the microcontroller. A tripping mechanism trips the circuit breaker in response to detection of a fault condition. The tripping mechanism trips the circuit breaker in response to receiving a trip signal from the microcontroller. The microcontroller is programmed to modify the bi-stable display when sending the trip signal to the electronic switching device. The bi-stable display shows an indication of one of the several fault types that would have caused the circuit breaker to trip. The bi-stable display continues to display the fault-type indication after the circuit breaker has tripped and power is interrupted to the microcontroller. | 06-17-2010 |