Ground fault detection for PCB and isolation grounds
First Claim
1. A ground fault detection system for use in detecting a ground fault condition in electronic equipment that includes a circuit ground electrically isolated from an isolation ground, where the ground fault condition occurs when the circuit ground shorts to the isolation ground, comprising:
- a capacitive sensor capacitively coupled to the system isolation ground, such that a sensor capacitance of the capacitive sensor is representative of an electrical condition of the system isolation ground; and
a capacitance-to-data conversion (CDC) unit coupled to the capacitive sensor, and referenced to the circuit ground, and including;
capacitance acquisition circuitry to acquire measurements of sensor capacitance for the capacitive sensor; and
data conversion circuitry to convert the sensor capacitance measurements into sensor data representative of the electrical condition of the system isolation ground, including an isolated condition in which the circuit ground is isolated from the system isolation ground, and a ground fault condition in which the circuit ground shorts to the system isolation ground.
1 Assignment
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Accused Products
Abstract
A ground fault detection system based on capacitive sensing suitable for use in detecting a ground fault condition in electronic equipment (such as a PCBA) with a circuit ground electrically isolated from an isolation ground (such as chassis ground). The capacitive sensing system includes a capacitive sensor capacitively coupled to the system isolation ground, and a capacitance/data converter that captures sensor capacitance measurements for conversion to sensor data representative of a ground short. In one embodiment, the capacitive sensor includes a sensor electrode capacitively coupled to the system isolation ground by one of projected capacitance and a floating capacitor (such as 33 pf), and the CDC unit further includes sensor excitation circuitry configured to drive the sensor electrode, such that a sensor capacitance (projected or floating capacitance) is representative of an electrical condition of the system isolation ground. For sensing by projected capacitance, the capacitive sensor can include a driven shield.
1 Citation
18 Claims
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1. A ground fault detection system for use in detecting a ground fault condition in electronic equipment that includes a circuit ground electrically isolated from an isolation ground, where the ground fault condition occurs when the circuit ground shorts to the isolation ground, comprising:
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a capacitive sensor capacitively coupled to the system isolation ground, such that a sensor capacitance of the capacitive sensor is representative of an electrical condition of the system isolation ground; and a capacitance-to-data conversion (CDC) unit coupled to the capacitive sensor, and referenced to the circuit ground, and including; capacitance acquisition circuitry to acquire measurements of sensor capacitance for the capacitive sensor; and data conversion circuitry to convert the sensor capacitance measurements into sensor data representative of the electrical condition of the system isolation ground, including an isolated condition in which the circuit ground is isolated from the system isolation ground, and a ground fault condition in which the circuit ground shorts to the system isolation ground. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A capacitance-to-data conversion (CDC) circuit for use in detecting a ground fault condition in electronic equipment with a circuit ground electrically isolated from an isolation ground, where the ground fault condition occurs when the circuit ground shorts to the isolation ground, the electronic equipment including a capacitive sensor capacitively coupled to the system isolation ground, such that a sensor capacitance of the capacitive sensor is representative of an electrical condition of the system isolation ground, the CDC circuit comprising:
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capacitance acquisition circuitry to couple to the capacitive sensor, and to acquire measurements of sensor capacitance for the capacitive sensor; the CDC circuit referenced to the circuit ground; and data conversion circuitry to convert the sensor capacitance measurements into sensor data representative of the electrical condition of the system isolation ground, including an isolated condition in which the circuit ground is isolated from the system isolation ground, and a ground fault condition in which the circuit ground shorts to the system isolation ground. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for detecting a ground fault condition in electronic equipment that includes a circuit ground electrically isolated from an isolation ground, where the ground fault condition occurs when the circuit ground shorts to the isolation ground, the method comprising:
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disposing in the equipment a capacitive sensor for capacitively coupling to the system isolation ground, such that a sensor capacitance of the capacitive sensor is representative of an electrical condition of the system isolation ground; and including in the electronic equipment a capacitance-to-data conversion (CDC) unit referenced to the circuit ground, the CDC unit operable for; acquiring measurements of sensor capacitance from the capacitive sensor; and converting the sensor capacitance measurements into sensor data representative of the electrical condition of the system isolation ground, including an isolated condition in which the circuit ground is isolated from the system isolation ground, and a ground fault condition in which the circuit ground shorts to the system isolation ground. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification