Wetting current diagnostics
First Claim
1. A method of providing wetting current diagnostics for a load control switch, the method comprising:
- detecting a state of the load control switch;
measuring a current level of a wetting current;
when the detected state is an open state, determining, based on the measured current level, whether the state of the load control switch is detected correctly by comparing the measured current level to first and second open switch current thresholds;
when the detected state is a closed state, comparing the measured current level to a closed switch current threshold; and
providing at least one of;
(i) a voltage offset fault alert if the measured current level falls between the first and second open switch current thresholds and if a measured voltage is above a voltage reference, the measured voltage measured at a node through which the wetting current passes to the load control switch, and (ii) a leakage fault alert if the measured current level falls between the first and second open switch current thresholds and the measured voltage is below the voltage reference.
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Accused Products
Abstract
A circuit for diagnostic testing includes a current source coupled to a power source and configured to provide wetting current along a path to a load control switch, a current sensor connected in series with the current source along the path, the current sensor being configured to generate a current sensor signal indicative of a current level along the path, a voltage measurement unit having an input terminal coupled to a node along the path through which the wetting current flows to reach the load control switch, the voltage measurement unit being configured to detect a state of the load control switch based on a voltage at the node, and a controller coupled to the current sensor and the voltage measurement unit, the controller being configured to determine a wetting current diagnostic condition in accordance with the current level and the detected state.
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Citations
18 Claims
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1. A method of providing wetting current diagnostics for a load control switch, the method comprising:
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detecting a state of the load control switch; measuring a current level of a wetting current; when the detected state is an open state, determining, based on the measured current level, whether the state of the load control switch is detected correctly by comparing the measured current level to first and second open switch current thresholds; when the detected state is a closed state, comparing the measured current level to a closed switch current threshold; and providing at least one of;
(i) a voltage offset fault alert if the measured current level falls between the first and second open switch current thresholds and if a measured voltage is above a voltage reference, the measured voltage measured at a node through which the wetting current passes to the load control switch, and (ii) a leakage fault alert if the measured current level falls between the first and second open switch current thresholds and the measured voltage is below the voltage reference. - View Dependent Claims (2, 3)
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4. A method of providing wetting current diagnostics for a load control switch, the method comprising:
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providing, by a current source coupled to a power source, a wetting current along a path to the load control switch; generating, by a current sensor connected in series with the current source along the path, a current sensor signal indicative of a current level along the path; detecting, by a voltage measurement unit having an input terminal coupled to a node along the path through which the wetting current flows to reach the load control switch, a state of the load control switch based on a voltage at the node; determining, by a controller coupled to the current sensor and the voltage measurement unit, a wetting current diagnostic condition in accordance with the current level and the detected state of the load control switch; if the current level is above an open threshold current level with the load control switch in an open position, deactivating, by the controller, the current source to determine a voltage level at the node with the current source deactivated; generating, by the controller, a voltage offset fault alert if the voltage level remains above a threshold voltage level upon deactivation; and generating, by the controller, a leakage fault alert if the voltage level falls below the threshold voltage level upon deactivation. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. A method of providing wetting current diagnostics for a load control switch, the method comprising:
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providing, by a current source coupled to a power source, a wetting current along a path to the load control switch; generating, by a current sensor connected in series with the current source along the path, a current sensor signal indicative of a current level along the path, the current sensor comprising a diode disposed in the path and a current mirror connected across the diode; receiving, by a current measurement unit coupled to the current sensor, the current sensor signal; comparing, by the current measurement unit, the current level with an open switch threshold and a closed switch threshold, the current measurement unit comprising a voltage comparator and a resistive load driven by the current mirror; detecting, by a voltage measurement unit having an input terminal coupled to a node along the path through which the wetting current flows to reach the load control switch, a state of the load control switch based on a voltage at the node; determining, by a controller connected to the current measurement unit and the voltage measurement unit, a wetting current diagnostic condition in accordance with the comparisons and the detected state; and comparing, by the voltage comparator, a voltage across the resistive load with a reference voltage. - View Dependent Claims (12, 13, 14)
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15. A method of providing wetting current diagnostics for a load control switch, the method comprising:
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providing, by a current source coupled to a power source, a wetting current along a path to the load control switch; generating, by a current sensor connected in series with the current source along the path, a current sensor signal indicative of a current level along the path; receiving, by a current measurement unit coupled to the current sensor, the current sensor signal; comparing, by the current measurement unit, the current level with an open switch threshold and a closed switch threshold; detecting, by a voltage measurement unit having an input terminal coupled to a node along the path through which the wetting current flows to reach the load control switch, a state of the load control switch based on a voltage at the node; and determining, by a controller connected to the current measurement unit and the voltage measurement unit, a wetting current diagnostic condition in accordance with the comparisons and the detected state; wherein the current sensor comprises a resistor disposed in the path and a transistor coupled to the resistor such that a voltage drop across the resistor controls an extent to which the transistor is activated. - View Dependent Claims (16, 17, 18)
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Specification