Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Reexamination Certificate
2000-03-23
2001-06-12
Barrera, Ray (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
C340S638000
Reexamination Certificate
active
06246304
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of circuit breakers, and more particularly to circuit breakers having an external visual indication of a trip condition.
BACKGROUND OF THE INVENTION
In the field of electrical circuit breakers, it is well known to provide an external indication of the internal state of the circuit breaker, for example ON, OFF, and TRIPPED.
A circuit breaker is a device, which serves to interrupt electrical current flow in an electrical circuit path upon the occurrence of an overcurrent in the circuit path. When the overcurrent occurs, the external toggle handle will normally return to the OFF position. However, a service technician of other user will have no indication whether the breaker was intentionally turned OFF or the breaker tripped. In complex breaker installations, where some breakers are normally maintained in an OFF position, this can make analysis difficult. Therefore, the art has taught the desirability of an external indication of switch state.
Various methods are available for indicating a Trip State of a breaker. First, the external toggle handle may be provided with a “mid-trip” state, intermediate from the ON and OFF states. This is typically accomplished by a linkage between the external toggle and trip mechanism, wherein, upon a trip condition of the breaker, the trip mechanism assumes a state, which causes the external toggle to lie in an intermediate state. See, e.g., U.S. Pat. Nos. 5,264,673, 4,528,531, 3,970,976, 3,955,162, and 3,863,042, expressly incorporated herein by reference. An electronic indicator may also be provided, for example, a light emitting diode, which is selectively illuminated by power from the load. See, e.g., U.S. Pat. No. 3,806,848, expressly incorporated herein by reference, or by means of an auxiliary switch, see, U.S. Pat. Nos. 3,742,402, 3,742,403, 3,863,042 and 3,955,162, expressly incorporated herein by reference. Some circuit breakers have an internal trip condition distinct from the OFF condition. See, e.g., U.S. Pat. No. 5,777,536. This latter solution, however, causes the problem that in the tripped condition, a small current still flows through the device. Other types of mechanical visual indicators are also possible. See, e.g., U.S. Pat. Nos. 5,847,913; 5,264,818; 5,089,796; 4,801,906; 4,446,042; 4,382,270; 4,251,789; 3,742,403; 3,742,402; 3,596,219: and 3,596,218, expressly incorporated herein by reference.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention therefore provides a mechanical latch which, upon tripping of the breaker, allows an externally visible mechanical element to visibly indicate a trip condition.
The mechanical latch does not require substantial modifications or adaptations of the normal circuit breaker and trip mechanisms, and without modification of the form factor or substantial modification of the circuit breaker housing, and thus is compatible with a wide range of breaker designs and applications.
The external mechanical indication of trip state according to the present invention also is manually resettable, although it is possible to provide an additional linkage for resetting the trip indicator while the breaker is reset.
According to a preferred design, a spring loaded plunger is provided protruding through the front of the circuit breaker housing. The plunger itself is designed to be visible, for example having a contrasting color and sufficient physical size. The plunger has a latch portion, disposed internal to the circuit breaker housing, which is capable of selectively retaining the plunger in a non-indicating position. An arm, within the breaker housing, is provided to retain the latch portion during normal use and switching of the breaker. However, during a trip condition, the collapsing mechanism actuates the arm to release it from the latching portion. The latch portion preferably comprises a protruding portion of a cylindrical body of the plunger, while the arm is preferably pivotally mounted within the housing, one end retaining the latch portion while the other end being disposed along a path of a collapsing portion of the trip mechanism, such that during a trip condition, the arm is displaced to release tie plunger to the trip indicating position.
If desired, a mechanism may be provided to automatically reset the external indicator when the circuit breaker is reset. For example, a cam or other linkage may be provided which retracts the external indicator when the handle is moved to the OFF position.
It is therefore an object of the invention to provide an external indicator for a trip state of a breaker which is compatible with existing circuit breaker packaging and form factors.
It is a further object according to the present invention to provide an automatic external indication of circuit breaker trip status.
These and other objects will be apparent from an understanding of the preferred embodiments.
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Airpax Corporation, LLC
Barrera Ray
Milde Hoffberg & Macklin, LLP
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