Patent Application
20090205939
1. Technical Field
This disclosure relates to circuit breakers, and more particularly, to a circuit breaker having a moisture resistant push to test button.
2. Description of the Related Art
Circuit breakers with ground fault or arc fault systems typically include a self-test button. These button designs usually include a mechanical spring, a secondary contact, and a hard plastic Push to Test (PTT) button. The test button is typically biased by a mechanical force provided by the spring. As the test button is depressed, the mechanical spring makes contact with a secondary contact. The secondary contact can be made of a similar material as the mechanical spring and may have spring type properties, or the secondary contact may be a stationary pin mounted on a printed circuit board (PCB).
One disadvantage is that a gap between the test button and a housing of the circuit breaker is present before or during when the button is depressed. When the gap between the button and the housing is present, several concerns arise related to moisture, corrosion, and potential electric shock. With the gap present, internal components are exposed to outside moisture and/or other containments that could disable the tripping functions of the test button. Although PCB's are typically conformally coated, this does not guarantee that moisture could not damage the PCB and/or related electrical components and disable the push to test button.
From a manufacturing standpoint, special care needs to be taken to ensure the contacting surfaces are not subject to corrosion or water damage. Current designs may be subject to corrosion on the contact surfaces if the mechanical parts were not properly coated, thus, disabling the push to test button functions. Further, the possibility of the user being exposed to electrical shock may be present.
A circuit breaker includes a housing forming an opening. A push switch is connected to a test circuit to enable testing of the test circuit in accordance with closing the push switch. A flexible membrane is formed in the opening and configured to form a seal between the housing and the flexible membrane. The flexible membrane is located in an operative relationship with the push switch such that pushing the flexible membrane results in a displacement of the push switch.
A flexible membrane for covering a button opening in a circuit breaker housing includes a planar section dimensioned and configured to cover an opening in a housing of a circuit breaker. A raised portion is centrally formed on the planar portion. Walls are formed about a perimeter of the planar section and form a groove about the perimeter of the planar section. The walls extend outward from the parallel portion. The walls are configured to clamp on housing walls of the circuit breaker to form a seal to exclude moisture and contaminants from the housing at the opening.
These and other objects features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
This disclosure will present in detail the following description of preferred embodiments with reference to the following figures wherein:
The present principles provide a push to test button that protects internal electrical components from moisture damage and/or other containments that could disable a circuit breaker device. In addition, the present principles provide protection for the user from an electrical shock due to the internal circuitry. The present embodiments reduce the concern for damage or injury due to moisture or other contaminants entering between the push to test button and an electronic housing of the circuit breaker. The present aspects minimize any gaps around the push to test button thus reducing the possibility of moisture or other materials from seeping in the electronic compartment and disabling the circuit breaker device. An improved seal for the button reduces the risk of electrical shock that may be present with a gap.
The present invention is not limited to the illustrative example and may be employed with other electrical devices and components. The present embodiments are illustratively described with reference to a push to test button, but may be employed with any button or device that enters through the housing wall of a circuit breaker. All statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Thus, for example, it will be appreciated by those skilled in the art that the diagrams presented herein represent conceptual views of illustrative system components and/or circuitry embodying the principles of the invention.
Referring now in specific detail to the drawings in which like reference numerals identify similar or identical elements throughout the several views, and initially to
Breaker 10 is depicted as a single pole breaker; however, multiple pole breakers (e.g., two pole circuit breakers) may be employed as well that include the push to test button 14 for tripping the device 10. The circuit breaker 10 may include any design having AFCI and/or GFCI protection and include thermal/magnetic protection and electronic components used to trip the circuit. A handle 16 is provided to switch the breaker 10 on or off or to reset the breaker 10 after a trip. A wire coil 18 is shown and employed for connecting the breaker 10 for operation.
Referring to
Different breaker designs may include different pole mechanisms for tripping the breaker. However, many designs include a fixed and moveable contact, where the moveable contact is attached to a moveable arm. The moveable arm is tripped under current surges and overload conditions. For GFCI and AFCI circuits, an electronic protection circuit on PCB 28 is provided that senses ground faults or arcing faults. A circuit (e.g., on the PCB 28) may be tested to determine proper operation by pressing the push to test button 14. Push to test functions are known in the art.
Referring to
In one embodiment, the flexible membrane 15 extends over and below walls 38 of the housing 12. The dimensions of the groove 36 are preferably undersized to provide a snug fit with housing walls 38. The flexible membrane 15 is preferably formed from a dielectric material with a sufficient thickness and/or dielectric constant to prevent electrical shock to a user during operation. Any moisture or liquids in contact with the breaker 10 will not be permitted to enter the breaker 10 through the push to test button 14 as a result of the seal provided by the flexible membrane 15. With no gap present, users are limited to any exposure to electrical shock. Further, the flexible membrane 15 becomes the push to test button for the device 10, making the assembly more moisture/humidity/contaminant resistant near the test button area as compared to conventional designs.
Referring to
The flexible membrane 15 covers an opening in the circuit breaker housing. The membrane 15 includes a planar section 40 dimensioned and configured to cover the opening in the housing 24 (and 26) of the circuit breaker 10. A raised portion 42 is centrally formed on the planar section 40. The raised portion may be above the planar section 40, be below the planar section 40 or both. Walls 34 are formed about a perimeter of the planar section 40 and form a groove 36 about the perimeter of the planar section 40. The walls 34 extend outward from the planar section 40. The walls 34 are configured to clamp on housing walls 24 and 26 of the circuit breaker 10 to form a seal to exclude moisture and contaminants from the housing at the opening. The clamp on the housing walls 24 and 26 is preferably caused by an interference fit between the groove 36 and the housing walls 24 and 26.
The self-test is performed on the breaker to determine whether the breaker 10 is capable of ground or arc fault detection. The push to test button may be employed to disable the breaker. A reset button may also be employed to reset the power (turn the power back on) after a test. It should be understood a circuit breaker may have one or more buttons and the that present principles are directed to all of these buttons. For example, the push to test buttons may include a test button and/or a reset button. Other buttons may also be employed and benefit for the present teachings.
Having described preferred embodiments for moisture resistant push to test button for circuit breakers (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the invention disclosed which are within the scope and spirit of the invention as outlined by the appended claims. Having thus described the invention with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.
This application claims priority to provisional application Ser. No. 61/029,584 filed on Feb. 19, 2008, incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61029584 | Feb 2008 | US |
