Patent Application
20080142486
1. Field of the Invention
The present invention relates in general to circuit breakers and, more particularly, to circuit breaker with a wireless sensor and adjustable arc-flash protection levels.
2. Description of the Related Art
Circuit breakers are generally well known and used in numerous applications normally to interrupt an electric circuit when certain predetermined conditions are met, although they may be used for other purposes. Typically the predetermined conditions are based on a current level drawn by the circuit to which the circuit breaker is attached, which level, depending on the application, may vary from a few amperes to hundreds or even thousands of amperes. A typical circuit breaker might include a set of separable contacts that can be separated when the set of predetermined conditions to open the circuit are reached. As the separable contacts begin to move away from each other, an electrical arc flash oftentimes forms between the separable contacts. As clearly understood by those of ordinary skill, electrical arc flashes are a safety hazardous to those maintaining or testing energized gear because of the elevated temperatures that these arc flashes may reach, which temperatures may range from about 3000 K to 30,000 K, depending on the current level. Thus, at least for safety reasons, the need for circuit breakers with adjustable levels of arc-flash protections has been recognized.
For example, U.S. Patent Application No. 2005/0219775, published on Oct. 6, 2005, discloses a low-voltage circuit breaker with maintenance trip functions that override the normal or specified trip functions of the breaker in order to reduce pickup currents and/or time delays to effect faster trips, thus reducing arc energy produced by faults during maintenance or testing on a live circuit breaker. In the disclosed apparatus, normal trip functions are overridden by the maintenance trip functions through actuation of a maintenance switch hardwired directly onto the trip unit where the same is accessible at the front of the circuit breaker. Nevertheless, although the device disclosed in the '775 patent application provides for the adjustment of fault levels, at least one of its significant setbacks relates to the fact that the maintenance switch is a hard-wired connection to the circuit breaker, requiring operator intervention. In other words, if maintenance and/or test personnel maintaining and/or testing an energized gear forgets to switch to the maintenance trip functions to lower the protection level, no protection is provided, exposing the user to the potential of an arc flash associated with an accidental fault. In addition, since the switch is hard-wired to the circuit breaker, it can only be changed by an operator physically in direct contact with the breaker, which may be located in a location different from where the maintenance or test is being carried out, thus again increasing the likelihood that the level of protection will not be lowered when needed.
It would therefore be desirable in order to increase the protection provided and to eliminate operator intervention to develop a circuit breaker trip unit capable of reducing the arc energy during the presence of an individual in a specified area around the breaker using a remote wireless sensing mechanism. By sensing the presence of the individual within the predetermined area via a wireless sensor, different level of the protection may be adjusted, including, but not limited to, instantaneous pickup current, short delay pickup, short time delay, ground fault delay, and ground fault time delay, to name a few, without operator intervention.
One or more of the above-summarized needs and others known in the art are addressed by circuit breakers that include a microprocessor and a wireless sensor in communication with the microprocessor, the wireless sensor being configured to detect the presence of a person in a predetermined area around the circuit breaker such that a level of protection of the circuit breaker is changed by the microprocessor when the presence of the person within the predetermined area is detected by the wireless sensor.
Methods of reducing a level of arc-flash protection of a circuit breaker are also within the scope of the disclosed invention, such methods including the steps of detecting the presence of a person within a predetermined area around the circuit breaker with a wireless sensor in communication with a microprocessor of the circuit breaker; and changing a level of protection of the circuit breaker when the presence of the person within the predetermined area is detected by the wireless sensor.
The above brief description sets forth rather features of the present invention in order that the detailed description that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, other features of the invention that will be described hereinafter and which will be for the subject matter of the appended claims.
In this respect, before explaining several preferred embodiments of the invention in detail, it is understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which disclosure is based, may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing Abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, one of the embodiments of a circuit breaker with adjustable flash protection and a wireless sensor according to disclosed invention will be described.
In operation, the circuit breaker 10 is initially programmed to operate with a normal level of protection. If an overload occurs on the circuit to which the circuit breaker 10 is connected, the microprocessor sends a signal to the flux shifter 20 and a trip unit (not shown) of the circuit breaker 10 is tripped. In addition, a range of the wireless sensor 18 characterizes a predetermined zone, such that, whenever the presence of a person is detected within that zone, that detection is communicated to the microprocessor 16 and the level of protection provided by circuit breaker 10 is reduced such that the flux shifter 20 will trip the circuit breaker 10 when the current signal 12 reaches the reduced level set in the microprocessor 16 in view of the fact that a person has been detected in the predetermined zone. Once a person leaves the safety zone, the microprocessor 16 may be programmed to reset the level of protection to normal or to any other desired level.
As such, if maintenance and/or test personnel maintaining and/or testing an energized gear containing the circuit break 10 walks into the predetermined zone, as detected by the wireless sensor 18, the level of arc-flash protection is automatically lowered without the need for that person to reach to the circuit breaker 10 or any other switch hardwired thereto, thus minimizing or eliminating the risk that the user will be exposed to the potential of an arc flash associated with an accidental fault. As such, the circuit breaker 10 according to the disclosed invention increases the level of arc-flash protection while eliminating the need for operator intervention during the presence of an individual in an area around the breaker characterized by the use of the remote wireless sensing mechanism. By sensing the presence of the individual within the unsafe area via a wireless sensor, different level of the protection may be adjusted, including, but not limited to, instantaneous pickup current, short delay pickup, short time delay, ground fault/earth delay, ground/earth fault time delay, longtime pickup, long time delay, protective relay protection (over-voltage, under-voltage, under-current, voltage unbalance) pickup and delay to name a few.
As understood by those of ordinary skill in the art, any wireless sensor device or module may be used in the instant invention. For example, but not a limitation, the wireless sensor 18 may be physically connected to the microprocessor 16 of the circuit breaker 10 by radio communication, the internet, and/or a hand-held computing wireless device, to name a few.
In another embodiment of a circuit breaker 30 according to the disclosed invention, as illustrated in
In use, the trip unit (not shown) of the circuit breaker 30, upon detection of motion of a person within a specified range from the wireless sensor 42 (e.g., 200 meters), decreases its instantaneous protection set point, allowing the circuit breaker 30 to trip faster. A front panel LED configured to flash at a pre-determine frequency controlled by the microprocessor 40 may be used to indicate the presence of a person within the room. An LCD, LED, and/or a Relay Output may also be used to indicate to the operator if the trip unit is on the standard protection mode or in a low arc-energy-protection mode. Also the trip unit may include an internal programmable relay that can be configured to implement this feature. If enabled, the contact may be configured to change state when the presence of a person is detected within the room where the wireless sensor 42 is disposed. The contact may be connected to an alarm system and the breaker may be configured to allow the user the ability to turn-off this protection either by a keypad (not shown) and/or a switch (not shown) on the trip unit. When the trip unit senses a presence of an individual within the circuit breaker room (or predetermined unsafe area) via the wireless sensor 42 located strategically within the room, it automatically changes the make current release, or MCR, high instantaneous, or HSET, and/or other protection set points and delays to values predefined by a user. Also, the user has the ability to override this protection either by keypad, communication, and hardwire input, or a combination thereof. Similarly to the embodiment of
Methods of reducing arc-flash protection in a circuit breaker that includes a wireless sensor are also within the scope of the embodiments of the invention disclosed.
With respect to the above description, it should be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, form function and manner of operation, assembly and use, are deemed readily apparent and obvious to those skilled in the art, and therefore, all relationships equivalent to those illustrated in the drawings and described in the specification are intended to be encompassed only by the scope of appended claims.
In addition, while the present invention has been shown in the drawings and fully described above with particularity and detail in connection with what is presently deemed to be practical and several of the preferred embodiments of the invention, it will be apparent to those of ordinary skill in the art that many modifications thereof may be made without departing from the principles and concepts set forth herein. Hence, the proper scope of the present invention should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications and equivalents.
