Patent Description:
Medium voltage (MV) switching poles or circuit breakers use for example levers or shafts to connect several switching poles (usually <NUM>) mechanically to one drive. The poles themselves require a translational movement (like SF6 poles or vacuum poles). With levers and shafts, it is difficult to connect several switching poles unless they are arranged in one line.

<CIT> relates to an electric circuit breaker that includes at least one mobile contact. The contact is connected to operating means that includes an electric motor. Movement converting means are provided for converting rotary movement of the motor to translatory movement for linear movment of the mobile contact. The movement conversion means includes a first body, such as a screw, and a second body, such as a nut. The threads of the screw and the nut co-act in engagement with each other. <CIT> also relates to an electric plant that is equipped with such a circuit breaker, to the use of the breaker for breaking electric current, and to a method of breaking electric current with the aid of the circuit breaker.

There is a need to provide for an improved medium voltage circuit breaker switching pole.

Therefore, it would be advantageous to have an improved medium voltage circuit breaker switching pole.

In a first aspect, there is provided a medium voltage circuit breaker switching pole, comprising:.

The movable contact is configured to move along a longitudinal axis of the vacuum interrupter. A centre axis of the threaded drive element is parallel to the longitudinal axis of the vacuum interrupter. When in an open configuration the fixed contact and movable contact are separated from one another. When in a closed configuration the fixed contact and movable contact are in contact with one another. Rotation of the threaded drive element about its centre axis in a first direction is configured to transition the switching pole from the open configuration to the closed configuration. Rotation of the threaded drive element about its centre axis in a second direction counter to the first direction is configured to transition the switching pole from the closed configuration to the open configuration.

In this way, the rotational movement of a motor associated with the circuit breaker can be utilized itself in a direct manner, rather than transitioning to linear movement through levers or shafts. This leads to a simpler, more robust, switching pole and where a number of poles can be arranged more flexibly in relation to each other, whilst being driven from a common motor.

In an example, the centre axis of the threaded drive element is aligned along the longitudinal axis of the vacuum interrupter.

In an example, rotation of the threaded drive element about its centre axis in the first direction through a rotational angle of less than or equal to <NUM> degrees is configured to transition the switching pole from the open configuration to the closed configuration. Rotation of the threaded drive element about its centre axis in the second direction through a rotational angle of less than or equal to <NUM> degrees is configured to transition the switching pole from the closed configuration to the open configuration.

In this manner, a relatively small rotational movement leads to the required translational movement of the movable contact, that occurs within the required transition timescale.

In an example, an end of the threaded drive element distil to the movable contact comprises a ball bearing configured to rotate in a ball bearing socket.

In an example, the ball bearing and/or the ball bearing socket comprise a low friction surface material.

According to the invention, the switching pole comprises a threaded pushrod connected to the movable contact. The thread of the pushrod is configured to engage with the thread of the threaded drive element. Rotation of the threaded drive element is configured to move the threaded pushrod along the centre axis of the threaded drive element.

According to the invention, the threaded pushrod is movable connected to the movable contact. A contact pressure spring is configured to move the moveable contact relative to the threaded pushrod.

In an example, the threaded pushrod comprises an insulating material.

According to the invention, the threaded pushrod is configured not to rotate as the threaded drive element rotates.

In an example, an outer surface of the threaded pushrod comprises a groove extending in an axial direction of the threaded pushrod. The groove is configured to engage with a fixed pin such that axial movement of the threaded pushrod leads to the fixed pin moving within the groove.

In an example, the threaded drive element comprises a coupling. The coupling is configured to engage with a gear wheel or belt associated with a drive motor. Rotational movement of the coupling is configured to lead to an associated and equivalent rotational movement of the threaded drive element.

In a second aspect, there is provided a medium voltage switching system, comprising:.

The first, second and third circuit breaker switching poles are configured to be driven by a single motor such that simultaneous rotation of each threaded drive of each switching pole is configured to transition each switching pole from the open configuration to the closed configuration.

In an example, rotation of the threaded drive element of each switching pole in the same direction is configured to transition each switching pole from the open configuration to the closed configuration.

In an example, rotation of the threaded drive element of the first and second switching poles in the same direction is configured to transition each switching pole from the open configuration to the closed configuration. Rotation of the threaded drive element of the third switching pole in the opposite direction is configured to transition the switching pole from the open configuration to the closed configuration.

In an example, at least one of the switching poles comprises a threaded drive element comprising an additional section to extend the length of the threaded drive element in the direction of its centre axis.

<FIG> relate to examples of a medium voltage circuit breaker switching pole. In an example, a medium voltage circuit breaker switching pole <NUM> comprises a fixed contact <NUM> of a vacuum interrupter, a movable contact <NUM> of the vacuum interrupter, and a threaded drive element <NUM>. The movable contact is configured to move along a longitudinal axis of the vacuum interrupter. A centre axis of the threaded drive element is parallel to the longitudinal axis of the vacuum interrupter. When in an open configuration the fixed contact and movable contact are separated from one another. When in a closed configuration the fixed contact and movable contact are in contact with one another. Rotation of the threaded drive element about its centre axis in a first direction is configured to transition the switching pole from the open configuration to the closed configuration. Rotation of the threaded drive element about its centre axis in a second direction counter to the first direction is configured to transition the switching pole from the closed configuration to the open configuration.

In an example, the thread of the threaded drive element is a high helix thread.

In an example, an end of the threaded drive element distil to the movable contact comprises a ball bearing configured to rotate in a ball bearing socket <NUM>.

In an example, the function of the ball bearing and/or the ball bearing socket <NUM> is fulfilled by an industrially available inclined ball bearing. This can comprise a low friction surface material.

In an example, the switching pole comprises a threaded pushrod <NUM> connected to the movable contact. The thread of the pushrod is configured to engage with the thread of the threaded drive element. Rotation of the threaded drive element is configured to move the threaded pushrod along the centre axis of the threaded drive element.

In an example, the threaded pushrod has a female thread and the threaded drive element has a male thread.

In an example, the threaded pushrod has a male thread and the threaded drive element has a female thread.

In an example, the threaded pushrod is movable connected to the movable contact. A contact pressure spring <NUM> is configured to move the moveable contact relative to the threaded pushrod.

In an example, the threaded pushrod is configured not to rotate as the threaded drive element rotates.

In an example, the threaded drive element comprises a coupling <NUM>. The coupling is configured to engage with a gear wheel or belt <NUM> associated with a drive motor <NUM>. Rotational movement of the coupling is configured to lead to an associated and equivalent rotational movement of the threaded drive element.

Thus, in this manner a thread is used to convert a rotational movement from a drive to a fast translational movement of the pole, where for example that thread can be a high helix thread giving a large translational movement for a relatively small rotational movement.

<FIG> also relate to a medium voltage switching system. In an example the system comprises: a first medium voltage circuit breaker switching pole as described above; a second medium voltage circuit breaker switching pole as described above; and a third medium voltage circuit breaker switching pole as described above. The first, second and third circuit breaker switching poles are configured to be driven by a single motor such that simultaneous rotation of each threaded drive of each switching pole is configured to transition each switching pole from the open configuration to the closed configuration.

Thus, the threaded drive elements all have right hand threads or left hand threads.

Thus, the threaded drive elements of two of the switching pols is right handed and the other pole has a threaded drive element that is left handed, or vice versa.

In an example, at least one of the switching poles comprises a threaded drive element comprising an additional section <NUM> to extend the length of the threaded drive element in the direction of its centre axis.

Thus, the manner in which the poles are driven enables several poles to be connected to one or more drives using toothed belts, chains, gear-wheels or alike, enabling arbitrary arrangement of the switching poles.

Continuing with the figures, the medium voltage circuit breaker switching pole and medium voltage switching system are described in further detail, with respect to specific embodiments.

<FIG> shows the switching pole in an open position, whilst <FIG> shows it in a closed position.

In <FIG> the vertical position of pushrod <NUM> is determined by the rotational angle of the drive element <NUM>. The spring <NUM> pushes the movable contact to the upper collar of the pushrod <NUM>. A distance between the fixed contact <NUM> and the movable contact <NUM> is the result. The vacuum interrupter VI is thus in an open configuration.

When the drive element <NUM> is rotated by a certain angle, the pushrod <NUM> moves upwards due to the thread. With industrially available high helix threads, it is possible to achieve the full stroke of the pushrod <NUM> with about one rotation of the drive element <NUM>. The upward movement of the pushrod <NUM> drives the movable contact against the fixed contact of the vacuum interrupter. A relatively small further upward movement of the pushrod <NUM> further compresses the contact pressure spring <NUM>, to ensure the required contact pressure.

The pushrod <NUM> is configured not to rotate during the upward or downward motion. This can be done in a number of different ways, with one way being to have a vertical groove in the pushrod <NUM> that runs over a pin that is fixedly connected to the environment.

As shown a ball bearing, consisting of the lower end of the drive element <NUM>, that is generally formed like a ball, and the fixed part of the ball bearing <NUM>, that is generally formed like a pit, is used to support the pushrod vertically against the force of the contact pressure spring <NUM>. The ball bearing also supports the switching pole <NUM> against lateral forces generated by the coupling <NUM> to a chain, belt or gear-wheel. The ball bearing joint can be formed in a known manner to minimise frictional forces.

The function of the ball bearing and/or the ball bearing socket <NUM> can as well be fulfilled by an industrially available inclined ball bearing.

<FIG> shows how three switching poles can easily be connected in a <NUM>° arrangement to a drive <NUM>. The switching poles <NUM> are in the closed position as an example. This arrangement is advantageous when the three switching poles are to be installed in a cylindrical enclosure.

Here, a drive system can have a double sided toothed belt <NUM> as an example. Alternatively, a chain or a single-sided toothed belt with pulleys can be used. The drive or motor <NUM> is located in the center as an example; other locations are also possible.

<FIG> shows how the connection of the three poles with the drives can be made with gear-wheels. The diameters of the gear-wheel of the drive and the gear-wheels of the poles can be adjusted to optimize the adaption of the torque and speed that the drive can generate to the torque and speed that is required for proper closing and opening operations of the switching poles.

What is further shown in <FIG> is that the poles can have different heights. This is controlled through the provision of an additional section <NUM> of the drive elements. This enables arbitrary positions of the switching poles, following the requirements of the environment of the circuit breaker CB, e.g. the air- or gas-insulated panel where the CB is installed.

Further, it is possible to connect more than one drive to the switching poles, when more drive power is required for a certain application. One drive can be used for a low-duty CB, while for a high-duty CB two drives can be used.

<FIG> shows an alternative way to connect three switching poles <NUM> to each other and to two drives <NUM>. It is required to use right-hand and left-hand threads alternately, as the sense of rotation of the gear-wheels changes from pole to pole, while the sense of translation of the pushrods has to be the same.

<FIG> shows a solution for a single pole having an individual drive. Depending on space constraints that may arise from the external switchgear, it can be advantageous to place the drive not below but to the side of the switching pole. The arrangement of pole and drive as shown in <FIG> can be hosted in a common insulating housing to form an integrated single pole CB, similar to the arrangement shown in <FIG>.

<FIG> shows a single pole having an individual drive <NUM> directly coupled to the drive element <NUM>. Here, the switching pole is in closed position. Thereby, any additional gear can be avoided. When the drive is controlled appropriately, for example using servomotors or stepper motors, then the travel curve of the moveable contact of the vacuum interrupter VI can also be appropriately controlled to the required level of precision with a minimum number of mechanical parts involved. This precise control is advantageous for example for synchronized switching or for constant closing and opening speeds independent of for example VI contact wear, temperature dependent friction or alike.

Claim 1:
A medium voltage circuit breaker switching pole (<NUM>), comprising:
- a fixed contact (<NUM>) of a vacuum interrupter (<NUM>);
- a movable contact (<NUM>) of the vacuum interrupter;
- a threaded pushrod (<NUM>); and
- a threaded drive element (<NUM>);
wherein, the movable contact is configured to move along a longitudinal axis of the vacuum interrupter;
wherein, the threaded pushrod is connected to the movable contact, and wherein the thread of the pushrod is configured to engage with the thread of the threaded drive element;
wherein, a centre axis of the threaded drive element is parallel to the longitudinal axis of the vacuum interrupter, wherein rotation of the threaded drive element is configured to move the threaded pushrod along the centre axis of the threaded drive element, and wherein the threaded pushrod is configured not to rotate as the threaded drive element rotates;
wherein, when in an open configuration the fixed contact and movable contact are separated from one another;
wherein, when in a closed configuration the fixed contact and movable contact are in contact with one another; and
wherein, rotation of the threaded drive element about its centre axis in a first direction is configured to transition the switching pole from the open configuration to the closed configuration, wherein the threaded pushrod is movable connected to the movable contact, wherein after the movable contact has been moved to contact the fixed contact the threaded pushrod is configured to continue to move towards fixed contact to compress a contact pressure spring (<NUM>) until a required contact pressure is obtained, and wherein rotation of the threaded drive element about its centre axis in a second direction counter to the first direction is configured to transition the switching pole from the closed configuration to the open configuration.