Method and apparatus for using direct current to detect ground faults in a shielded heater wire
First Claim
1. An ice and snow melting system, comprising:
- at least one sensor, each said sensor being configured for sensing one of temperature and moisture associated with an ambient environment and providing a signal indicative thereof;
a heater for melting the ice and snow, said heater including a heater wire, a layer of insulation substantially surrounding said heater wire, and a conductive shield substantially surrounding said layer of insulation;
a ground fault circuit interrupter, said ground fault circuit interrupter coupled with said shield of said heater, said ground fault circuit interrupter detecting a ground fault condition between said heater wire and said conductive shield and providing a signal indicative thereof;
a DC power supply configured for applying a DC voltage to said conductive shield one of directly and via said ground fault circuit interrupter; and
an automatic controller connected to said at least one sensor, said controller including heater control circuitry receiving each of said sensor signal and said ground fault circuit interrupter signal and selectively controlling operation of said heater dependent upon said sensor signal and said ground fault circuit interrupter signal.
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Accused Products
Abstract
An ice and snow melting system includes at least one sensor configured for sensing a temperature or moisture associated with an ambient environment and providing a signal indicative thereof. A heater for melting the ice and snow includes a heater wire, a layer of insulation substantially surrounding the heater wire, and a conductive shield substantially surrounding the layer of insulation. A ground fault circuit interrupter is coupled with the shield of the heater. The ground fault circuit interrupter detects a ground fault condition between the heater wire and the conductive shield and provides a signal indicative thereof. An automatic controller is connected to the at least one sensor. The controller includes heater control circuitry receiving each of the sensor signal and the ground fault circuit interrupter signal. The heater control circuitry selectively controls operation of the heater dependent upon the sensor signal and the ground fault circuit interrupter signal.
79 Citations
19 Claims
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1. An ice and snow melting system, comprising:
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at least one sensor, each said sensor being configured for sensing one of temperature and moisture associated with an ambient environment and providing a signal indicative thereof;
a heater for melting the ice and snow, said heater including a heater wire, a layer of insulation substantially surrounding said heater wire, and a conductive shield substantially surrounding said layer of insulation;
a ground fault circuit interrupter, said ground fault circuit interrupter coupled with said shield of said heater, said ground fault circuit interrupter detecting a ground fault condition between said heater wire and said conductive shield and providing a signal indicative thereof;
a DC power supply configured for applying a DC voltage to said conductive shield one of directly and via said ground fault circuit interrupter; and
an automatic controller connected to said at least one sensor, said controller including heater control circuitry receiving each of said sensor signal and said ground fault circuit interrupter signal and selectively controlling operation of said heater dependent upon said sensor signal and said ground fault circuit interrupter signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An ice and snow melting system, comprising:
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a heater for melting the ice and snow, said heater including a heater wire, a layer of insulation substantially surrounding said heater wire, and a conductive shield substantially surrounding said layer of insulation;
a DC power supply configured for applying a DC voltage to said conductive shield; and
a current detecting device coupled with said conductive shield and configured for detecting a DC current associated with said DC voltage in said conductive shield, said DC current flowing from said conductive shield to said heater wire. - View Dependent Claims (10, 11, 12)
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13. A method of controlling a heater used to melt ice and snow, said method comprising the steps of:
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providing the heater with a heater wire, a layer of insulation substantially surrounding said heater wire, and a conductive shield substantially surrounding said layer of insulation;
providing heater control circuitry for selectively controlling operation of the heater;
sensing one of temperature and moisture associated with an ambient environment with a sensor and providing a signal indicative thereof with said sensor;
transmitting said sensor signal to said heater control circuitry;
applying a DC voltage to said conductive shield without first applying the DC voltage to said heater wire;
detecting a DC current associated with said DC voltage in said conductive shield;
transmitting a signal indicative of said DC current associated with said DC voltage to said heater control circuitry; and
selectively controlling the operation of the heater with said heater control circuitry, dependent upon at least one of said sensor signal and said signal indicative of said DC current. - View Dependent Claims (14, 15)
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16. A method of controlling a heater used to melt ice and snow, said method comprising the steps of:
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providing the heater with a heater wire, a layer of insulation substantially surrounding said heater wire, and an ungrounded conductive shield substantially surrounding said layer of insulation;
applying a DC voltage directly to the conductive shield;
detecting a DC current associated with said DC voltage in the conductive shield; and
selectively controlling the operation of the heater dependent upon said detecting step. - View Dependent Claims (17, 18, 19)
providing heater control circuitry for selectively controlling operation of the heater;
using said ground fault interrupter to provide a signal indicative of a ground fault condition associated with the heater; and
transmitting said ground fault circuit interrupter signal to said heater control circuitry.
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Specification