Description
A system and a method for adjusting a length of an insulating rod for a high voltage circuit breaker and a high voltage circuit breaker
The present disclosure relates to a system and a method for adjusting a length of an insulating rod for a high voltage circuit breaker. The present disclosure is further related to a corresponding high voltage circuit breaker.
Circuit breakers are automatically operated electrical switches designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit, for example. Accordingly, a high voltage circuit breaker is a security switch or switch gear configured to act in the high voltage range of 10 kV or more, for example. Document EP 1 843 365 A2 discloses an actuating rod assembly comprising a control rod and a holder fitting at a control rod end. The holder fitting exhibits a hollow cylindrical recess with an inner superficial surface and an outer superficial surface. The inner superficial surface is formed by a holder fitting unit and the outer superficial surface is formed by a holder fitting unit. In this respect, it is a challenge to provide a stable and reliable circuit breaker for high voltage applications.
Embodiments of the present disclosure relate to a system for adjusting a length of an insulating rod for a high voltage circuit breaker. Further embodiments of the present disclosure relate to a corresponding high voltage circuit breaker including such a system. Further embodiments of the
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present disclosure relate to a method for adjusting a length of an insulating rod for a high voltage circuit breaker.
According to an embodiment, a system for adjusting a length 5 of an insulating rod of a high voltage circuit breaker
comprises a clutch and a fitting. The clutch is configured to couple the insulating rod with a lever of the high voltage circuit breaker to transmit an acting movement causing
separation of electrical contacts of the high voltage circuit breaker. The clutch includes a thread with a given thread pitch. The fitting also comprises a thread with a given thread pitch formed in coordination with the thread of the clutch. The fitting and the clutch are adjustably coupled with each other by means of their threads. The fitting is configured to be fixedly coupled with the insulating rod such that with respect to an assembled state of the system with the insulating rod and with respect to a longitudinal axis the length of the insulating rod is adjustable due to rotation of the clutch relative to the fitting by means of their threads.
Due to the described configuration of the system a secure and reliable length adjustment of the insulating rod of a high voltage circuit breaker is feasible at low cost. The clutch comprises a coupling section for connection with a lever mechanism of the circuit breaker and an adjustment section including the thread for adjusting an effective length of the insulating rod. The coupling section and the adjustment section are formed in one piece, for example. The fitting also comprises a coupling section for connection with the insulating rod of the circuit breaker and an adjustment section including the thread for adjusting the effective length of the insulating rod in interaction with the clutch. The fitting can also be formed in one piece, for example. Thus, the system is feasible with clear structure at low cost and forms an intermediate module between the lever mechanism and the insulating rod of the high voltage circuit breaker.
It is a recognition of the present disclosure that the performance of a high voltage circuit breaker depends on travel characteristics of arcing and nominal contacts. A
timing and a point of contact separation is of paramount importance for the circuit breaker's capability to interrupt the associated electrical circuit. The timing is mainly influenced by the travel characteristic of a drive and a linkage. Manufacturing tolerances are a major contributor to the inaccuracies of the linkage. In order to eliminate the influence of the assembly and manufacturing tolerances, the length of the insulating rod can be adjusted during the assembly process by rotating the clutch relative to the fitting.
By use of the system it is possible to ensure a correct timing of the electrical contact separation, despite manufacturing tolerances of interrupter parts. The system contributes to simplify adjustment of the length of the insulating rod and thus to compensate for manufacturing and assembly tolerances to a defined value.
According to an embodiment the fitting is shaped as a sleeve and its thread is formed as an internal thread on an inside of the fitting. The thread of the clutch is formed as an external thread on an outside of the clutch such that with respect to an assembled state of the system the clutch extends into the sleeve-shaped fitting. Such a configuration enables a secure and reliable length adjustment only by use the fine threads of the clutch and the fitting.
For example, the threads of the clutch and the fitting are formed in coordination with each other and comprise given thread pitches such that a rotation of the clutch by 180° relative to the fitting around the longitudinal axis causes a change of the length of the insulating rod of 0.5 mm. According to further embodiments, the thread pitches can be
formed alternatively to enable ever more precise adjustments or a coarser settings of the length of the insulating rod. In particular a rotation of the clutch by 180° relative to the fitting around the longitudinal axis causes a change of the length of the insulating rod by half of the thread pitches.
In context with this description, the described length of the insulating rod does not relate to the original fix length of the formed insulating rod element but the effective length of the original length of the insulating rod in sum with the adjustable length provided by the clutch and the fitting and their engaged threads.
According to a further embodiment, the system comprises a securing member that is coupled with the clutch configured to counteract an unwanted rotation of the clutch relative to the fitting. For example, the securing member is formed as a locking pin or bolt. In this respect, the fitting and the clutch each comprises a securing opening and the locking pin is inserted into these securing openings after length adjustment to counteract a further rotation of the clutch. Alternatively or additionally the securing member can comprise a nut to fix the adjusted clutch. The nut can further enable to beneficially reload the threads of the clutch and the fitting. However, there is no need for a complex assembly using a lot of elements to adjust the length of the insulating rod during assembly. Moreover, there is no need for an additional adhesive to fix the adjusted position of the clutch relative to the fitting.
In view of conventional designs the described system does not require a torque application and a usage of an adhesive to secure the adjustable elements. On the one hand, the application of torque at the clutches of the insulating rod
increases the risk of mechanical failures due to overloading adjacent parts. On the other hand, there is a decisive risk that an applied adhesive does not cure properly, thereby loosening the adjusted connection. The adhesive carries a risk that it is dirty and/or greasy and thus it does not dry out reliably.
Thus, using the described system a risk for assembly errors is reduced as well due to its clear structure. The system provides a convenient and secure way of adjusting the length of the insulating rod during assembly and the adjustment does not require any tools to be carried out.
According to a further embodiment the fixed position of the clutch relative to the fitting can be further secured in place by means of a fixation element. Such a fixation element can be formed as a spring clip configured to fix the position of securing member with respect to an assembled and adjusted state of the system and the insulating rod.
According to a further embodiment of the system, the clutch is shaped as a sleeve in a region of its thread limiting an inner relief recess. Such a consciously formed opening can contribute to an improved force and tension distribution. The relief recess can completely penetrate the clutch along the longitudinal axis, for example. Alternatively, the relief recess is formed into the adjustment section of the clutch with a given depth. The shape of the relief recess can be a cone tapering in direction towards the coupling section. Alternatively, with respect to the longitudinal axis the relief recess is cylindrical limited by a surrounding wall of the clutch supporting the thread.
The longitudinal axis basically represents a symmetrical axis of the clutch, the fitting and the insulating rod. Thus, according to an assembled state, the fitting is arranged between the clutch and the insulating rod along the longitudinal axis. The longitudinal axis can also represent the axis of rotation of the clutch relative to the fitting.
The clutch is made from steel, for example. The insulating rod can also be made from steel. The fitting is made from aluminium, for example, and fixedly glued to the insulating rod.
According to a further embodiment of the system, the fitting comprises a support section limiting a support recess facing towards the clutch. The clutch comprises a shoulder section adjacent to its adjustments section with its thread. The support section of the fitting and the shoulder section of the clutch are formed in coordination with each other such that a guided and supported coupling of the clutch and the fitting is set. The fitting can be realised as a sleeve or a tube comprising an opening facing the clutch. In the support section a wall of the fitting limits the support recess to guide the insertion of the clutch and to support it in its adjusted state in interaction with the shoulder section of the clutch. The support section is formed adjacent to the thread, for example. The support recess can be manufactured as a drilling forming a guide hole with sliding fit.
The threads of the clutch and the fitting can each comprise a length with respect to the longitudinal axis which is formed predetermined in dependence of a tensile strength of the fitting with respect to an assembled state of the fitting with insulating rod. Alternatively or additionally, the
thread of the clutch comprises a diameter across the longitudinal axis which is formed predetermined in dependence of a material and/or a tensile strength of the fitting with respect to an assembled state of the fitting with insulating rod. The threads of the clutch and the fitting are formed as fine threads to enable precise adjustment and also a stable and reliable holding of the interacting clutch, fitting and insulating rod. Thus, the diameter and/or the length of the threads is formed as large and/or as long as possible to enable full support of acting forces.
According to an embodiment, a high voltage circuit breaker comprises an insulating rod that is configured to separate electrical contacts of the high voltage circuit breaker, and an embodiment of the aforementioned system for adjusting a length of the insulating rod. The system is directly or indirectly coupled with the insulating rod by means of the fitting. As a result of that the high voltage circuit breaker comprises an embodiment of the system, described features and characteristics of the system are also disclosed with respect to the high voltage circuit breaker and vice versa.
According to an embodiment, a method of adjusting a length of an insulating rod of a high voltage circuit breaker comprises providing the clutch and the fitting with respective threads and given thread pitches. The method further comprises coupling the fitting with the clutch by means of screwing using the threads such that the clutch is adjustable coupled with fitting. The method further comprises coupling the fitting fixedly with the insulating rod. The coupling of the fitting with the insulating rod can be done afterwards to the coupling of the clutch with the fitting or beforehand. The method further comprises rotating the clutch relative to the
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fitting with respect to a longitudinal axis and thereby adjusting the length of the insulating rod.
The described method enables simple and precise adjustment of the length of the insulating rod of a high voltage circuit breaker during assembly and contribute to a stable and reliable functioning of the circuit breaker. As a result of that the method corresponds to an adjustment process using an embodiment of the aforementioned system, described features and characteristics of the system are also disclosed with respect to the method and vice versa.
According to an embodiment of the method, the clutch and the fitting each comprises a securing opening and the method further comprises providing a securing member, for example formed as a locking pin. The method further comprises inserting the locking pin into the securing openings of the fitting and the clutch and thereby fixing the clutch rotation ally relative to the fitting with respect to the longitudinal axis.
The present disclosure comprises several aspects, wherein every feature described with respect to one of the aspects is also disclosed herein with respect to the other aspect, even if the respective feature is not explicitly mentioned in the context of the specific aspect.
The described system, the described high voltage circuit breaker and the described method allow for reducing a risk of thread loosening during operation. There is no need for an additional fixing component such as an adhesive to establish a secure and stable hold. Moreover, the system enables to reduce a risk of overloading adjacent parts during assembly.