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Overload Detection Mechanism for Electrical Wiring

IP.com Disclosure Number: IPCOM000246654D
Publication Date: 2016-Jun-24
Document File: 3 page(s) / 27K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is an electrical cord that is capable of independently detecting an overload on the associated specific wire composition and then acting upon that condition, regardless of any present circuit protection features in the power source or the load that may exceed the cord's capability. Additionally, the system can deliberately trigger a non-integrated Ground Fault Circuit Interrupter (GFCI) based on a condition of current overload rather than the existence of a ground fault.

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Overload Detection Mechanism for Electrical Wiring

Electrical wiring can be overloaded and catch fire. Many times this occurs without warning.

The common widespread solution to this problem is the use of circuit breakers and fuses, some of which may be driven or supplemented by thermal detection. The problem with the current approach is that an electrical system or device behind the breaker/fuse might contain multiple smaller wires, which cannot carry enough current to trip the breaker before becoming overloaded.

Consider an extension cord capable of carrying 10 amps, which is plugged into a house power circuit with a 20-amp circuit breaker. A heater drawing 15 amps, with an internal overload protection breaker, is then plugged into the extension cord.

This is a common occurrence. The result is the extension cord is overloaded, may become dangerously hot and cause a fire. The power circuit's breaker does not trip because no more than 20 amps are being drawn. Similarly, the heater's overload protection breaker does not trip because no more than 15 amps are being drawn. The problem is that a cord with an insufficient duty rating was used, but there is no way to prevent this or detect it when it occurs.

Currently, extension cords carry warning labels regarding maximum current draws (sometimes expressed in wattage assuming a standard 115 VAC power source). However, most users do not read these warnings, or do not understand how much power devices use and whether that exceeds the rating of the applied cords.

The novel contribution is a cord that is capable of independently detecting an overload on the associated specific wire composition and then acting upon that condition, regardless of any present circuit protection features in the power source or the load that may exceed the cord's capability. Additionally, the system can deliberately trigger a non-integrated Ground Fault Circuit Interrupter (GFCI) based on a condition of current overload rather than the existence of a ground fault.

Consider a two- or three-wire extension cord. Sensors measure voltage across supply lines at the beginning (source) and end (destination) of the cord, and then calculate the voltage drop with known resistance in the wire to determine how much current is flowing. If the flow is over a predetermined amount, then do one or more of the following:


 Shunt a small amount of current to ground (10ma) in a three-wire cord, in order to trip a GFCI of any amperage rating


 Light or flash a light-emitting diode (LED) at the source and/or destination end of the cord


 Sound an audible alarm


 Respond to radio frequency identification (RFID) interrogation that an overload condition exists


 Send a wired or wireless signal to a central monitor that an overload condition

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exists

Alternatively, the cord can use heat sensors at the source, the destination, or throughout the cord's length to detect an overload condition. The system can also use oth...