Electrical fault detection system
First Claim
1. A microcontroller-based system for detecting ground-fault and grounded-neutral conditions in an electrical power distribution system having line and neutral conductors, comprising a sensor producing an output signal responsive to current flow in both the line and neutral conductors of the electrical power distribution system, a circuit interrupter for interrupting current flow in said power distribution system in response to a trip signal, a microcontroller receiving said sensor output signal and initiating the generation of a trip signal upon detection of a ground-fault or a grounded-neutral condition in said power distribution system, said microcontroller being programmed to use said sensor output signal to detect ground-fault conditions during spaced time intervals, and use said sensor output signal to detect grounded-neutral conditions during intervening time intervals between said spaced interval.
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Accused Products
Abstract
A microcontroller-based system to detect ground-fault and grounded-neutral conditions in a monitored circuit of an electrical distribution system having line and neutral conductors. The system includes a single sensor producing an output signal responsive to current flow in both the line and neutral conductors of the monitored circuit, and a microcontroller receiving the sensor output signal and initiating the generation of a circuit status signal indicating one of a normal operating condition, a ground-fault condition or a grounded-neutral condition in the monitored circuit. The microcontroller is programmed to continuously test for ground-fault conditions by evaluating the sensor output signal and, at selected intervals, test for grounded-neutral conditions by evaluating the sensor'"'"'s output signal response to a microcontroller initiated ping in the sensor circuit.
11 Citations
26 Claims
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1. A microcontroller-based system for detecting ground-fault and grounded-neutral conditions in an electrical power distribution system having line and neutral conductors, comprising
a sensor producing an output signal responsive to current flow in both the line and neutral conductors of the electrical power distribution system, a circuit interrupter for interrupting current flow in said power distribution system in response to a trip signal, a microcontroller receiving said sensor output signal and initiating the generation of a trip signal upon detection of a ground-fault or a grounded-neutral condition in said power distribution system, said microcontroller being programmed to use said sensor output signal to detect ground-fault conditions during spaced time intervals, and use said sensor output signal to detect grounded-neutral conditions during intervening time intervals between said spaced interval.
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15. A microcontroller-based system for detecting ground-fault and grounded-neutral conditions in an electrical power distribution system having line and neutral conductors, comprising
a sensor, containing a single current transformer producing an output signal responsive to current flow in both the line and neutral conductors of the electrical power distribution system, a microcontroller receiving said sensor output signal and initiating the generation of a trip signal upon detection of said ground-fault or said grounded-neutral condition in said power distribution system, said microcontroller being programmed to use said sensor output signal to detect ground-fault conditions during spaced time intervals, and use said sensor output signal to detect grounded-neutral conditions during intervening time intervals between said spaced time intervals, and a circuit interrupter for interrupting current flow in said power distribution system in response to said trip signal.
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16. A method of detecting ground-fault and grounded-neutral conditions in an electrical power distribution system having both line and neutral conductors, comprising
producing a signal responsive to current flow in both the line and neutral conductors of the electrical power distribution system, supplying said signal to a microcontroller that is programmed to use said signal to detect ground-fault conditions during spaced time intervals, use said signal to detect grounded-neutral conditions during intervening time intervals between said spaced intervals, initiate the generation of a trip signal upon detection of a ground-fault or a grounded-neutral condition, and interrupting current flow in said power distribution system in response to said trip signal.
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22. A method of detecting ground-fault and grounded-neutral conditions in an electrical power distribution system having both line and neutral conductors and a sensor circuit producing a signal responsive to current flow in both the line and neutral conductors of the electrical power distribution system, comprising
using a real-time clock to produce spaced time intervals, sampling said signal at said spaced time intervals, using the signal sample from each spaced time interval to detect a ground-fault condition, and setting a ground-fault indicator in response to the detection of a ground-fault condition, using said signal sample to detect a neutral-to-ground fault condition, and setting a neutral-to-ground fault indicator in response to the detection of a neutral-to-ground fault condition, initiating the generation of a trip signal in response to the setting of a ground-fault or a neutral-to-ground indicator, and interrupting current flow in said power distribution system in response to said trip signal.
Specification