Patent Application
20170169979
The present disclosure relates to methods and systems for adding fault detection and interruption to the branch circuits of an ordinary thermal-magnetic circuit breaker equipped load center panelboard.
There is a large installed base of residential load centers which rely on simple thermal-magnetic circuit breakers which only protect branch circuits by the detection of overcurrent conditions resulting in a trip of the circuit breaker and separating its movable contacts. Typical circuit breakers in the home must be reset manually by operation of the circuit breaker handle.
The electrical panel or panelboard, typically known as a “load center” in residential applications, has a main bus connected to individual branch circuits through individual connection points on the bus that are connectable to the circuit breakers for each branch circuit conductor. The branch circuit conductors supply electricity to the various loads within the residence. Because the circuit breakers, sometimes referred to herein simply as “breakers” for convenience, rely on simple thermal-magnetic protection, they may not provide full protection to all electrical malfunctions in the home. As a safety measure it is increasingly necessary to monitor and control branch circuits in the home for arc faults of both of the parallel and series arc types, i.e. combined arc fault interruption (CAFI), and for ground fault interruption (GFI). Protection against all these faults together is referred to as “dual function” protection.
Thus it would be desirable to provide the breakers of basic residential load centers with more protection capability through a simple and economical retrofit process.
While the illustrated embodiments are explained with load centers in mind, and the terms “load center” and “panelboard” may sometimes be used interchangeably herein, the present invention is not necessarily limited to the miniature circuit breaker load center environment.
Aspects of the present invention may provide a retrofit remote control module for fitting between a branch circuit breaker and the load. The remote control module can provide the simple thermal-magnetic circuit breakers with arc fault or ground fault, or both, sensing and interruption capabilities. The retrofit remote control module may comprise a case which houses a current path represented by neutral and line conductors through the remote control module and appropriate connectors for connecting the module between the load side conductors of a simple thermal-magnetic circuit breaker and the downstream branch circuit wiring. The remote control module may further comprise line sensors for the current path and electronics connected to said line sensors which operate to detect the selected type of ground faults and arc faults to be controlled; and operate a bistable relay in the current path between the branch breaker and the load.
In some implementations, the line sensors/electronics may detect series arcs, or parallel arcs, or both. In some implementations the line sensors/electronics may detect ground faults. In some implementations, the line sensors/electronics may detect ground faults and both types of arc faults to provide so-called “dual function” circuit interruption.
In some implementations, the retrofit CAFI/GFI remote control module may have its bistable relay electromechanically operated while in other implementations the bistable relay could alternatively be a solid state relay. In some implementations, it may be desirable that the bistable relay has a push to test (PTT) button and a manual reset button extending from the case. In some implementations, it may be desirable that the retrofit CAFI/GFI remote control module have a communications link for receiving remote instructions to close, i.e. reset, the bistable relay.
Space considerations within the load center may dictate that the retrofit modules preferably be stand-alone modules which can be connected and function outside of the load center enclosure. In such cases it is desirable that the case of the module is sealed/weatherproofed against the intrusion of water and dirt. In other cases it may be desirable to locate the modules in an enclosure outside an adjacent load center containing the circuit breakers which need the additional functionality of the modules.
The foregoing and other advantages of the disclosed embodiments will become apparent upon reading the following detailed description and upon reference to the exemplary explanatory drawings offered to illustrate the invention according to one or more embodiments disclosed herein, wherein:
As an initial matter, it will be appreciated that the development of an actual, real commercial application incorporating aspects of the disclosed embodiments will require many implementation specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation specific decisions may include, and likely are not limited to, compliance with system related, business related, government related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time consuming in an absolute sense, such efforts would nevertheless be a routine undertaking for those of skill in this art having the benefit of this disclosure.
It should also be understood that the embodiments disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Thus, the use of a singular term, such as, but not limited to, “a” and the like, is not intended as limiting of the number of items. Similarly, any relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like, used in the written description are for clarity in specific reference to the drawings and are not intended to limit the scope of the invention.
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While particular aspects, implementations, and applications of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the scope of the disclosed embodiments as defined in the appended claims.
