Apparatus and method for detecting electrical resistance change in connectors to a remote mounted sensor
AssigneeHoneywell Inc.
InventorBruch Lyman Hill
Life of this patent
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Abstract
A control system detects an electrical resistance change in a connector coupling a remote mounted temperature sensor to a control system. A control system determines the resistance of the sensor or the connector by selectively charging or discharging a capacitor through a unidirectional circuit element or the sensor. The control system is disclosed as controlling a water heater system, although such control systems may be used to control other systems using remote mounted sensors. A calibrating circuit is used to measure a transient response of an RC circuit, from which resistance can be derived.
Claims22
A method for detecting a measured connector resistance in a connector coupling a remote mounted sensor to a microcontroller and a capacitor, the connector having a predetermined resistance, the method comprising:
- coupling a unidirectional current element in parallel with the remote mounted sensor to form a remote mounted sensor net;
- coupling the remote mounted sensor net to the microcontroller and the capacitor via the connector to form an RC circuit including at least the remote mounted sensor net, the connector, and the capacitor;
- determining a first transient response associated with the RC circuit and being characterized by current substantially flowing through the unidirectional current element and the connector and substantially bypassing the remote mounted sensor;
- and
- determining the measured connector resistance in the connector from the first transient response.
A device for detecting a resistance change of a connector as seen by a control circuit looking into the connector connecting a remote circuit to the control circuit, the device comprising:
- a unidirectional current element electrically connected in parallel with the remote circuit, the unidirectional current element and the remote circuit being coupled to the control circuit via the connector;
- a non-linear passive circuit element in the control circuit coupled to the remote circuit and the unidirectional current element via the connector, wherein the non-linear passive circuit element, the unidirectional current element, the remote circuit, and the connector form at least a portion of an RC circuit;
- and
- a microcontroller coupled to the connector and to the non-linear passive circuit element and being further coupled to the unidirectional current element via the connector, the microcontroller being configured to:
- detect a first response time of a first transient signal in the RC circuit and resulting from transient current flowing substantially through the connector and the unidirectional current element and bypassing substantially the remote circuit,
- determine a first resistance of the connector and the unidirectional current element based on the first response time, and
- compare the first resistance to a predetermined resistance for the connector and the unidirectional current element to detect a derogation in the connector.
A water heater control system comprising:
- a unidirectional current element electrically connected in parallel with a remote circuit, the unidirectional current element and the remote circuit being coupled to the control circuit via a connector;
- a non-linear passive circuit element in the control circuit coupled to the remote circuit and the unidirectional current element via the connector, wherein the non-linear passive circuit element, the unidirectional current element, the remote circuit, and the connector form at least a portion of an RC circuit;
- and
- a microcontroller coupled to the connector and to the non-linear passive circuit element and being further coupled to the unidirectional current element via the connector, the microcontroller being configured to:
- detect a first response time of a first transient signal in the RC circuit and resulting from transient current flowing substantially through the connector and the unidirectional current element and bypassing substantially the remote circuit,
- determine a first resistance of the connector and the unidirectional current element based on the first response time, and
- compare the first resistance to a predetermined resistance for the connector and the unidirectional current element to detect a derogation in the connector.
Apparatus for detecting a measured connector resistance in a connector coupling a remote mounted sensor to a microcontroller and a capacitor, the connector having a predetermined resistance, the apparatus comprising:
- means for coupling a unidirectional current element in parallel with the remote mounted sensor to form a remote mounted sensor net;
- means for coupling the remote mounted sensor net to the microcontroller and the capacitor via the connector to form an RC circuit including at least the remote mounted sensor net, the connector, and the capacitor;
- means for determining a first transient response associated with the RC circuit and being characterized by current substantially flowing through the unidirectional current element and the connector and substantially bypassing the remote mounted sensor;
- and
- means for determining the measured connector resistance in the connector from the first transient response.
A method for detecting a resistance change in a connector coupling a remote mounted sensor to a microcontroller and a capacitor, the method comprising:
- coupling a unidirectional current element in parallel with the remote mounted sensor to form a remote mounted sensor net;
- coupling the remote mounted sensor net to the microcontroller and the capacitor via the connector to form an RC circuit including at least the remote mounted sensor net, the connector, and the capacitor;
- determining a first transient response associated with the RC circuit and being characterized by current substantially flowing through the unidirectional current element and the connector and substantially bypassing the remote mounted sensor;
- determining a second transient response associated with the capacitor and being characterized by current substantially flowing through a calibration resistor;
- and
- detecting the resistance change in the connector based on the first transient response and the second transient response.
A device for detecting a resistance change of a connector as seen by a control circuit looking into the connector connecting a remote circuit to the control circuit, the device comprising:
- a unidirectional current element electrically connected in parallel with the remote circuit, the unidirectional current element and the remote circuit being coupled to the control circuit via the connector;
- a non-linear passive circuit element in the control circuit coupled to the remote circuit and the unidirectional current element via the connector to form an RC circuit including at least the remote mounted sensor net, the connector, and the capacitor;
- a calibration element coupled to the non-linear passive circuit element;
- a microcontroller coupled to the connector, the calibration element and the non-linear passive circuit element and being further coupled to the unidirectional current element and the remote sensor via the connector, the microcontroller being configured to:
- detect a first response time of a first transient signal in the RC circuit and resulting from transient current flowing substantially through the connector and the unidirectional current element,
- detect a second response time of a second transient signal across the non-linear passive circuit element and resulting from transient current flowing through the calibration element,
- determine a ratio of the first response time to the second response time, and compare the ratio to a predetermined threshold to detect a derogation in the connector.
Dependencies are inferred from the claim text.