HEATER WITH SIMULTANEOUS HOT SPOT AND MECHANICAL INTRUSION PROTECTION
First Claim
1. A heater having a durable construction for incorporation into a plurality of articles, said heater comprising:
- at least one continuous heating means, at least one continuous current leakage conductor, at least one continuous NTC sensing means, placed between, and electrically connected to said heating means and said current leakage conductor, said NTC sensing means provides current leakage between said heating means and said current leakage conductor;
at least one controller, for simultaneous protection from hot spot and mechanical intrusion into said heater, said hot spot is detected by measuring the imbalance of electrical current flowing between live and neutral ends of the electrical circuit of said heating means;
1 Assignment
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Accused Products
Abstract
An electrical heater utilizes negative temperature coefficient material (NTC) and current imbalance between live and neutral ends of the heater to simultaneously protect the heater from the hot spot and mechanical intrusion into the heating cable. The NTC layer, separating the heating wire and current leakage conductor, becomes electrically conductive at the temperatures above 60° C., thus “leaking” the current to earth. The hot spot is detected by measuring the current imbalance between line and neutral connections of the heating cable. The mechanical intrusion into the heater, such as cable or insulation damage, water or sharp metal object penetration, is also simultaneously measured by the same current imbalance measuring system such as Ground Fault Circuit Interrupter (GFCI). The optional return conductor and metal foil/mesh hot spot detection shields cancel electromagnetic field. The heater may contain positive temperature coefficient (PTC) continuous sensor to control the temperature in the heater. Such PTC sensor can be made of electrically conductive fibers and/or metal wires.
53 Citations
19 Claims
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1. A heater having a durable construction for incorporation into a plurality of articles, said heater comprising:
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at least one continuous heating means, at least one continuous current leakage conductor, at least one continuous NTC sensing means, placed between, and electrically connected to said heating means and said current leakage conductor, said NTC sensing means provides current leakage between said heating means and said current leakage conductor;
at least one controller, for simultaneous protection from hot spot and mechanical intrusion into said heater, said hot spot is detected by measuring the imbalance of electrical current flowing between live and neutral ends of the electrical circuit of said heating means;
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification