The present invention relates to operator mechanisms for circuit breakers.
Circuit breakers are one of a variety of overcurrent protection devices used for circuit protection and isolation. The circuit breaker provides electrical protection whenever an electric abnormality occurs.
In a power transmission or distribution network, switching apparatuses are incorporated into the network to provide automatic protection in response to abnormal load conditions or to permit opening or closing (switching) of sections of the network. The switching apparatus may therefore be called upon to perform a number of different operations such as interruption of terminal faults or short line faults, interruption of small inductive currents, interruption of capacitive currents, out-of-phase switching or no-load switching, all of which operations are well known to a person skilled in the art.
One type of circuit breaker is a vacuum circuit breaker that open and close primary circuits using vacuum interrupters (VI). A device used to open and close the VI is the operating mechanism or unit (e.g., often a modular, self-contained unit). The operating mechanism is configured to maintain opening and closing energy and facilitate closing an opening of the operation mechanism. Stated differently, in switching apparatuses, the actual opening or closing operation is carried out by two contacts where normally one is stationary and the other is mobile. The mobile contact is operated by an operating assembly that includes an actuator and an operator mechanism, where the operator mechanism operatively connects the actuator to the mobile contact.
Actuators of known operating devices for medium and high voltage switches and circuit breakers are of the spring operated, the hydraulic or the electromagnetic type. An operator mechanism converts the motion of the actuator, e.g., spring-actuated drive unit into a translation movement of the mobile contact. A spring operated actuator, or spring drive unit as it is also called, generally uses two springs for operating the circuit breaker; an opening spring for opening the circuit breaker and a closing spring for closing the circuit breaker and reloading the opening spring. In its closed position the mobile contact and the stationary contact of the circuit breaker are in contact with each other and the opening spring and the closing spring of the operating device are charged. Upon an opening command the opening spring opens the circuit breaker, separating the contacts. Upon a closing command the closing spring closes the circuit breaker and, at the same time, charges the opening spring. The opening spring is now ready to perform a second opening operation if necessary. When the closing spring has closed the circuit breaker, the electrical motor in the operating device recharges the closing spring. This recharging operation takes several seconds. The circuit breaker can be locked in open and closed operational status using trip latch open and trip close latch units that lock the operator mechanism in the stated positions. Examples of spring actuated drives are described in U.S. Pat. Nos. 4,678,877 and 6,667,452, the contents of which are hereby incorporated by reference as if recited in full herein.
Unfortunately, conventional compression closing springs may apply a relatively large spring force that can present operational issues, e.g., the closing spring force may push up on a main shaft when it is charged and put a large moment on the shaft with potentially undue stress on shaft bearings and/or misalignment in operational components such as a frame in communication with the shaft. There remains a need for alternate operator mechanisms for circuit breakers and switches.
Embodiments of the present invention are directed to operator mechanisms with spring-actuated drives that include at least one clock spring held on a cam shaft with a drive cam configured to close a circuit breaker.
The at least one clock spring can be configured as a closing spring of the operator mechanism that is configured to drive a pinion associated with an electric motor and that can be used without requiring a compression closing spring.
Embodiments of the invention are directed to actuator devices that include at least one clock spring comprising a disc shaped body with gear teeth and a spiral spring, a cam shaft holding the at least one clock spring with an inner end portion of the spiral spring attached to the cam shaft, and a drive cam held by the cam shaft adapted to be in communication with a follower that is mechanically linked to a circuit interrupter.
The actuator devices can direct an actuator to open or close a mobile contact to maintain open and closed energy status of the electrical circuit.
The at least one clock spring can be configured as a closing spring of the spring operated actuator.
The disc shaped body of the at least one clock spring can have an outer perimeter with the gear teeth. The gear teeth can be in communication with a pinion of a clutch attached to an electric motor.
The at least one clock spring can include a plurality of clock springs.
The plurality of clock springs can all attached to the drive cam shaft such that rotation of the drive cam shaft in a defined direction compresses the spiral springs.
The drive cam can have a perimeter with a plurality of spaced apart lobes and a plurality of spaced apart valleys, the lobes and valleys can be arranged such that adjacent lobes are separated by a respective valley. Each lobe can define a closing point and each valley can define an opening point of the electrical circuit.
The drive cam can include three lobes and three valleys.
The drive cam can include two lobes and two valleys.
The at least one clock spring can be a plurality of clock springs that can be releasably attached to the drive cam shaft for modular build configurations.
The scalable configuration allows the use of the design across different rated circuit breakers including different ranges of voltages and/or different ranges of current (e.g., about 630 A to about 315 A) and/or different ranges of short circuit currents (e.g., about 25 kA, about 31.5 kA, about 40 kA, and about 50 kA).
The drive cam can have a cam profile with three lobes and three valleys with the valleys associated with trip open positions of a circuit breaker and the lobes associated with trip closed positions of the circuit breaker. A minima radian of a respective valley can be circumferentially separated from an adjacent maxima radian of a respective lobe by between about 5 to about 20 degrees.
The drive cam can have a cam profile with two lobes and two valleys, with the valleys associated with trip open positions of a circuit breaker and the lobes associated with trip closed positions of the circuit breaker. A minima radian of a respective valley can be circumferentially separated from an adjacent maxima radian of a respective lobe by between about 5 to about 20 degrees.
The inner end portion of a respective spiral spring of the at least one clock spring can be configured to extend as a planar segment across a center gap space inside turns of the spiral spring. The cam shaft can have an outer end portion with a radially extending slot that slidably receives the planar segment of a respective spiral spring.
The devices can include a trip latch in communication with the drive cam to lock the drive cam in a trip open and/or trip closed position.
In some embodiments, the trip latch includes a first stop cam and a second stop cam held on the cam shaft.
The device can include a follower residing against the drive cam and a main shaft in communication with the follower configured to maintain open and closed energy status of the circuit breaker responsive to a position of the drive cam and the trip latch.
The drive cam can have a plurality of spaced apart working positions about its perimeter allowing multiple holding locations for trip open and trip closed positions in a single revolution.
Still other embodiments are directed to operator mechanisms for an electrical circuit of a circuit breaker or electrical switching apparatus. The mechanisms include: (a) at least one clock spring comprising a disc shaped body with gear teeth and a spiral spring, wherein the at least one clock spring is configured as a closing spring; (b) a cam shaft holding the at least one clock spring with an inner end portion of the spiral spring attached to the cam shaft; (c) a drive cam held by the cam shaft adapted to be in communication with a follower that directs an actuator to open or close a mobile contact to maintain open and closed energy status of the electrical circuit; (d) a follower held by a linkage in cooperating alignment with the drive cam; (d) an electric motor having a clutch with a pinion, the pinion in communication with the gear teeth of the at least one clock spring; and (e) a main shaft in communication with the linkage and arranged to cause the actuator to open or close the electrical circuit.
The disc shaped body of the at least one clock spring can have an outer perimeter. The gear teeth reside on the perimeter and are in communication with the pinion of a clutch attached to an electric motor.
The at least one clock spring can include a plurality of clock springs. The plurality of clock springs can all be attached to the drive cam shaft such that rotation of the drive cam shaft in a defined direction compresses the spiral springs.
The drive cam can have a perimeter with a plurality of spaced apart lobes and a plurality of spaced apart valleys, such that adjacent lobes are separated by a respective valley, and wherein each lobe defines a closing point and each valley defines an opening point of the electrical circuit
The drive cam can include three lobes and at least three valleys.
The drive cam can include two lobes and at least two valleys.
The drive cam can have a profile with a first lobe that merges into two adjacent shallow valleys, that merge into a second lobe that then merges into two adjacent shallow valleys.
The at least one clock spring can be a plurality of stackable clock springs that can be releasably attached to the drive cam shaft. Inner end portions of the spiral springs extend as axially spaced apart planar segments across a center gap spaced formed by turns of the spiral spring. The single rotatable shaft includes an outer end portion with a radially extending slot that slidably receives the planar segments of the spiral springs.
Other embodiments are directed to operator mechanisms for an electrical circuit of a circuit breaker that include: (a) a cam shaft; a drive cam held by the cam shaft, with the drive cam having a cam profile with a plurality of lobes and valleys, the valleys associated with trip open positions of the circuit breaker and the lobes associated with trip closed positions of the circuit breaker thereby providing multiple hold locations for trip open and trip closed positions in a single revolution of the drive cam; (b) a follower held in cooperating alignment with the drive cam; an electric motor having a clutch with a pinion, the pinion in communication with the cam shaft; and (c) a linkage in communication with the follower that directs an actuator to open or close a mobile contact to maintain open and closed energy status of the electrical circuit.
A minima radian of a respective valley can be circumferentially separated from an adjacent maxima radian of a respective lobe by between about 5 to about 20 degrees.
Other embodiments are directed to methods of using a spring-actuated closing spring in a circuit breaker. The methods include: (a) automatically rotating a drive cam shaft holding at least one drive cam and at least one clock spring with a respective spiral spring, wherein one of the at least one clock gear comprises gear teeth; (b) automatically compressing and uncompressing a respective spiral spring of the at least one clock spring responsive to winding and unwinding rotation directions of the drive cam shaft; (c) turning a pinion gear associated with clutch attached to an electric motor based on rotation of the clock spring gear teeth; and (d) opening and closing an electric circuit based on whether the drive cam is in an open position or a closed position.
Successive opening and closing operations can be carried out based on drive cam movements of less than 90 degrees with the drive cam configured to rotate in a single direction and provide a plurality of serially alternating closing and opening points about its 360 degree perimeter.
Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.
It is noted that aspects of the invention described with respect to one embodiment, may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below.
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. Like numbers refer to like elements and different embodiments of like elements can be designated using a different number of superscript indicator apostrophes (e.g., 40, 40′, 40″, 40′″).
In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90° or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The term “about” refers to numbers in a range of +/−20% of the noted value.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In the following, operator mechanisms will be described operating a circuit breaker but similar known operating mechanisms may also operate switches.
The term “medium voltage” with respect to circuit breakers is conventionally meant with respect to a voltage level in the range of 1-72 kV. The term “high voltage” refers to a voltage level above 72 kV. The term “low voltage” refers to voltages below 1 kV.
Embodiments of the invention relate to an operator mechanism and/or electric switching apparatus that includes a clock spring-operated actuator. Preferably the switching apparatus is a medium or high voltage switching apparatus such as a medium or high voltage vacuum circuit breaker.
Referring now to the figures,
As shown in
The at least one clock spring 15 can be configured to provide an opposite force against the opening spring 88 (
The at least one clock spring 15 is the spring-actuated drive that causes the linkage 35 of the operator mechanism 10 and/or circuit breaker 100 to move to the linkage L to a trip close position (
The at least one clock spring 15 can be configured to operate with a smooth, high precision transmission and may reduce or eliminate unbalanced forces generated by conventional closing compression springs. The clock spring closing drive configuration can operate with a transmission precision with low rotational stiffness and can have the same storing and releasing operational direction.
The clock spring can reduce or eliminate force imbalances caused by some conventional compression closing spring arrangements and can reduce the spring volume by greater than 50% (typically by about 85%) to allow for a more compact configuration.
Still referring to
The clock springs 15 can have a scalable modular design to allow the same part (e.g., same size and shape clock spring) to be used in different numbers on a respective drive shaft 20 to meet different load requirements of different (typically medium) voltage vacuum circuit breakers 100. The scalable configuration can be such as to allow the use of the clock spring design across different circuit breakers including different rated circuit breakers including different ranges of voltages and/or different ranges of current (e.g., between about 630 A to about 315 A) and/or different ranges of short circuit currents such as between about 10 kA to about 100 kA (e.g., about 25 kA, about 31.5 kA, about 40 kA, and about 50 kA).
In some embodiments, the inner end 17i of the spring 17 of the clock spring 15 can be attached via an adhesive, coupler or other attachment member (not shown) not requiring a slot or used with the slot 20s.
The modular (scalable) configuration of the clock spring and accommodating cam shaft length 20 allows extensibility for multiple clock springs for a large and/or full series of different circuit breaker ranges. A desired number of clock springs 15 can be selected for a particular device so as to match a defined torque of the torque limited clutch 50 (
As shown in
When the circuit breaker 100 is triggered for an opening action, an opening spring, typically a torsion spring 88 (
In some embodiments, as shown in
The valley 26v can define a respective open position Po and the cam profile can have an arc (circumferential spacing) of between about 5-20 degrees from a minima radian of a valley 26v to a maxima radian of the cam outline at an adjacent lobe 26l for the next closed position Pc.
The lobe angular extension α may vary between different applications but for a two lobe design α1 (
Similarly, the valley angular extension β may vary between different applications but for a two valley design β1 (
Thus, in operation, by way of example of some embodiments, the drive cam 26 with the spiral spring 17 of the clock spring 15 will rotate and push the linkage 35 to close the contacts 100c (
The drive cam 26 can be configured to match a force output characteristic of the at least one clock spring 15. The point of output characteristic is typically larger than a load. The exemplary units on the graph of
The clock spring(s) 15 on the cam shaft 20 are closing springs and the motor M rotates to charge the clock springs 15.
In some particular embodiments, the operator mechanism 10 can optionally include a latch assembly 40 with at least one stop cam 20c and at least one latch member 40m as discussed briefly above. As shown in
In some embodiments, the trip latch assembly 40 can also include two latches, a trip-close latch 42 and a trip-open latch 44. The trip-open and trip-close latches 42, 44, respectively, can be held on a single trip latch shaft 46 as shown or may be held on separate shafts (not shown). The trip-close latch 42 is in cooperating alignment with the second stop cam 24 while the trip-open latch 44 is in cooperating alignment with the first stop cam 22. The trip-close and trip-open latches 42, 44, respectively, can move in response to the position and shape of the respective aligned stop cam 24, 22. Each stop cam 22, 24 can be keyed to the trip latch shaft 46 so that rotation of one stop cam can rotate the shaft and the other stop cam. Rotation of any cam 22, 24, 26 can rotate the shaft and other cam including the stop and drive cam. The stop cams 22, 24 can be fixed to the same stop cam shaft.
The first and second stop cams 22, 24 can each be configured to be able to hold the drive cam 26 in desired open and close positions so as to open and close the breaker 100 (
To change a “locked” status, a force F can be applied to the upper back portion 44b of the trip-open latch 44. This will pivot the trip-open latch 44 to disengage from the respective stop cam 22. In turn, this allows drive cam 26 to turn a sufficient amount before the trip-close latch 42 engages the next stop of the second stop cam 24 at trip open hold point one (H1)(
In some embodiments, the first and second stop cams 22, 24 can be configured to hold the drive cam 26 in a desired position associated with a closed or open breaker position while held on the same cam shaft 20 and can also be configured to carry out a latch unit recovery.
In some embodiments, the first and second stop cams 22, 24 can have the same size and shape, including the same cam surface perimeter profile shape. The trip-open and trip-close latches 42, 44 can also have the same shape and size. However, it is also contemplated that the stop cams 22, 24 can have different sizes and/or shapes as may respective latch members 42, 44.
The trip latch shaft 46 can be held at a position that is above and laterally offset from the cam shaft 26 to hold at least one of the trip-open or trip-close latch in cooperating alignment with a respective stop cam 20c.
Referring to
As shown, the stop cams 22, 24 can be configured to have at least one (shown as two) recovery point R. The at least one recovery point R resides between the holding points H1, H2. In the exemplary embodiment shown, the stop cams 22, 24 each have two circumferentially spaced apart recovery points R, one between each hold point H1, H2. The stop cams 22, 24 can be configured with a curvilinear shape that forms two holding point ledges and two fins that taper outward to a maximal radius R2 at the recovery point R, then extend straight in at an orthogonal surface to a segment having a first smaller radius R1 (
In some embodiments, the drive cam 26 can have two diametrically opposing arcuate lobes 26l circumferentially spaced apart by inwardly curved valleys 26v. However, other drive cam configurations may be used. For example, the drive cam 26 can include more than two circumferentially spaced apart lobes 26l.
In the trip close position, as shown in
The trip-close latch 42 and stop cam 24 can serially move so that the trip close latch 42 goes from being upstanding in the trip open position with the lower end of the leg 42e on the hold point H1 of the stop cam 24 (
The trip-open latch 44 and the stop cam 22 can serially move as shown in
The drive cam 26 moves as allowed by the stop cams 22, 24 and latch members 42, 44 to move the follower 33 and hence the main shaft 30. The drive cam 26 rotates from the trip open position with the follower in a valley 26v with the follower residing closer to the cam shaft 20 and/or stop cams 22, 24 (
The method can optionally include rotating a stop cam on the drive cam shaft to a hold position (block 205).
The drive cam can be held in a trip open position and a trip close position using a trip latch assembly (that typically, but optionally, includes one or more stop cams on the drive cam shaft) (block 210).
The method can include automatically rotating a pinion gear of a clutch associated with an electric motor using the gear teeth of the at least one clock spring (block 215).
The drive cam can have at least two circumferentially spaced apart lobes, with at least two valleys, one between each side of adjacent lobes (block 220).
The drive cam can have at least two separate open positions defined by respective valleys and two separate close positions defined by respective lobes (block 225).
The method can include automatically rotating a pinion gear of a clutch associated with an electric motor in response to rotation of the clock gear.
The method can be carried out to maintain opening and closing energy and facilitate closing an operation mechanism. Stated differently, the clock-spring can be an actuator drive for an actuator configured to a cause a mobile contact to close against another contact for a closing operation so that a the operator mechanism operatively connects the actuator to the mobile contact.
The latch assembly can be operated by pushing an upper portion of a trip-open latch toward a first stop cam held on a cam shaft also holding a drive cam and a second stop cam to release the trip-open latch from a stop defined by a holding point on a first stop cam; then automatically rotating the drive cam; then rotating a second stop cam so that a trip close-latch engages a stop at a holding point on the second stop cam to prevent further movement of the drive cam.
The clock spring 15 with the gear 16 can be configured to remain static except in an energy storage process. The clock spring 17 can release energy when the status of the breaker changes. When the cam shaft 20 rotates one revolution, the clock spring gear 15 can be driven by the transmission to make the spring 17 store energy. In some embodiments, the clock spring 15 can push the main cam shaft 26 to rotate a desired amount between a trip close to a trip open position. The desired amount can be between about 10-40 degrees, typically a small amount of between about 10-25 degrees, more typically between about 20-25 degrees, such as about 20 degrees, about 21 degrees, about 22 degrees, about 23 degrees, about 24 degrees and about 25 degrees, from a trip close to a trip open position.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.
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