JPH023284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum valve type on-load tap changer, and particularly to a method for maintaining accurate opening/closing timing between vacuum valves.

Figure 1 is an example of the main circuit for one phase of a commonly used vacuum valve type on-load tap changer, which has one resistor r, a vacuum valve R for the resistor, and two main vacuum valves A and B. The following shows the switching order of a one-resistance, three-vacuum-valve type on-load tap changer. One terminal of these vacuum valves is connected collectively to the neutral point, and the other terminals of the main vacuum valves A, B are connected to different adjacent taps T ₁ , T ₂ of winding 1 of the transformer, respectively.
The other terminal of the remaining vacuum valve R is connected to one of the tap selectors 2a and 2b via a current limiting resistor r (connected to 2b in the figure).

When switching from tap T ₁ to T ₂ of winding 1, the vacuum valve opens and closes in the order of 1, 2, 3, and 4 in the diagram, and when switching from tap T ₂ to T ₁ , the vacuum valve opens and closes in the order from 4 to 1. The valve opens and closes. In the figure, hatching indicates a closed state. While the main vacuum valve B is energized, the resistance vacuum valve R can of course be open, but because the current flowing due to the resistance r is small, it is closed and energized in parallel with the main vacuum valve B. However, since this is mechanically advantageous, the tap switching operation is generally performed between 1 and 4 or 4 and 1 in FIG.

Figure 2 is a diagram of the switching mechanism including the quick-acting mechanism 27 consisting of the crank 21, connecting rod 22, swing lever 23, switching lever 24, tension spring 25, and stopper 26, in which O ₁ , O ₂ , and O ₃ are fixed. The drive shaft is shown. As the crank 21 rotates clockwise about the drive shaft _O3 , the swing lever 23 to which the connecting rod 22 is connected performs a swing motion about the shaft _O1 . A fulcrum P provided at the tip of the swing lever 23
A tension spring 25 is attached between the fulcrum Q provided at the tip of the switching lever 24 fixed to the drive shaft O ₂ , and this spring is charged with energy according to the operation of the swing lever 23 . ₂ and P pass the point (dead center) where they are aligned on the same straight line, the stored energy is suddenly released and the switching lever 24 is moved until it is stopped by the stopper 26, thereby rotating the drive shaft _O2 .

A switching device 28 for opening and closing vacuum valves A, B, and R is provided on the drive shaft _O2 , and the vacuum valves B, R, and A are opened and closed by this operation. Figure 3 shows this operation diagram and the opening/closing sequence of the vacuum valve.
Indicates the switching order from T ₁ to T ₂ , 1 → 2 → 3
The tension spring 25 shown by the dotted line is activated between PQ and
By releasing the stored energy in step 4→7, each vacuum valve is opened and closed, and the tap switching is completed. Fig. 4 shows the switching order from tap T ₂ to T ₁ , in which the tension spring 25 between the supports P and Q stores energy in steps 1 to 2, and the switching is completed by releasing the energy in steps 3 to 6. . In addition,
3 and 4 correspond to FIG. 2.

FIG. 5 shows the opening/closing device 28 and vacuum valve operating mechanism 54 attached to the drive shaft 64 (O ₂ ).
2 indicates the closed state of the vacuum valve, and 2 indicates the open state of the vacuum valve. In the figure, a vacuum valve 51 has a fixed rod 52 in its vacuumed interior and a movable rod 53 that contacts the end of the fixed rod in the axial direction to close a circuit, and separates to open a circuit. Both rods 5 serve as the vacuum valve operation mechanism 54.
Pressure spring 5 provided on the extension of the shaft of 2,53
5. A cage 56 which houses a pressure spring 55 and whose one end engages with the tip of the movable rod 53 protruding into the air and pulls it away from the fixed rod 52, which is fixed to the other end of the cage 56 and guided to a support 57; a shoulder 59 attached to the tip of the guide rod 58; a pressure spring 60 surrounding the guide rod 58 between the shoulder 59 and the support 57; and a cam roller 61 rotatably supported by the shoulder 59.
Equipped with. The cam roller 61 opens and closes the vacuum valve 51, which is displaced in the axial direction of the movable rod 53 by the opening/closing device 28. The opening/closing device 28 is a cam roller 61
It consists of a cam 62 that pushes up the cam 62 and a rotating disk 63 that supports the cam 62 on its circumference.
4 (O ₂ ).

In Figure 6, the drive shaft 64 (O ₂ ) is at an angle θ = φ ₁ + α
This diagram schematically shows the movement of the cam roller 61 due to rotation by +β+γ+ _φ2 , and the distance connecting the center _O2 and the center of the cam roller 61 changes depending on each rotation angle. is drawn to move around the circumference of the cam 62. The drive shaft 64 rotates counterclockwise at an angle φ ₁ +
When the cam roller 61 rotates α+β+γ (φ ₁ is the idle rotation at the beginning of operation), the cam roller 61 moves on the cam 62, the vacuum valve closes, and then the cam rotates at an angle φ ₂ and then stops. From this state, drive shaft 6
4 rotates clockwise by an angle of φ ₂ +γ+β+α, the vacuum valve is completely opened, and then rotates with an idle angle of φ ₁ and the cam stops. Note that θ is the total rotation angle of the drive shaft 64.

Figure 7 is a torque diagram showing the torque of the drive shaft (O ₂ , 64 in Figure 5) required for opening and closing the vacuum valve in accordance with the rotation of the cam, and the cam rotation angles α, β, and γ are This corresponds to the rotation angle shown in Figure 6. 1 in Fig. 7 is when the vacuum valve is closed, and the cam 62 moves counterclockwise in Fig. 6, so
The shaft torque gradually increases from zero while compressing the tripping spring 60 shown in FIG. . At this point, the shaft torque increases rapidly, and the outer circumference 65 of the cam 62 increases.
The shaft torque reaches its maximum torque at the point where the cam roller 61 comes into contact with the angle β, and then gradually decreases to zero at the angle γ when the vacuum valve is applied with a predetermined external pressing force. When opening the vacuum valve, the operation is completely opposite to that described above, and the torque on the drive shaft also acts as negative, as shown in FIG. 7-2. That is,
Torque is applied to the drive shaft 64 in the positive direction when the vacuum valve is closed, and in the negative direction when the vacuum valve is opened.

Figure 8 shows a three-phase vacuum valve R that has the same effect.
In the opening/closing time chart when A and B open and close at the same time, the shaded area indicates the open state. FIGS. 9 and 10 show composite torque diagrams when the cam is placed on a rotating disk and driven so that all three-phase vacuum valves operate according to this time chart. These figures are a composite of the torque diagrams of the single vacuum valve shown in Figures 1 and 2, and the dotted line is the composite torque of the three phases. In the case of three-phase, three rotating disks are placed on the drive shaft, and three cams are placed on each rotating disk, and nine vacuum valves are opened and closed by these operations. Ru.

Figure 9 is a composite torque diagram when switching from tap _T2 , which is energized by a single main vacuum valve A, to tap _T1 , which is energized in parallel with main vacuum valve B and resistance vacuum valve R; As shown in the time chart in the figure, the process starts with the closing of the vacuum valve R of each phase and ends with the closing of the vacuum valve B. In this case, at the beginning of driving, the resultant torque becomes positive and acts as a drag force. The driving torque by the tension spring (FIG. 2, 25) is not shown because it always exceeds the resultant torque.

FIG. 10 is a composite torque diagram of the drive shaft when switching from tap _T1 to _T2 , starting with the opening of the vacuum valve B of each phase and ending with the opening of the vacuum valve R. In this case, at the beginning of driving, the resultant torque does not act as a drag force, but acts as a negative force, that is, a force that rotates the cam.

The mechanism for rapidly releasing the energy stored in the tension spring (Fig. 2, 25) is as shown in Fig. 3 (3) when switching from tap T ₁ → T ₂ and as shown in Fig. 4 (2) when switching from tap T ₂ → T ₁ . The condition is to pass the dead point.
However, at the dead center position, the torque applied to the swing lever (23 in Figure 2) is small, and the operation is influenced by mechanical frictional force, making it extremely unstable, so tap T ₁ →
T If there is no resistance at the beginning of driving, such as when switching between _two directions, the vacuum valve may start moving before the torque from the tension spring reaches the specified value, which has the disadvantage that accurate opening/closing speed and timing cannot be obtained. .

The present invention aims to correct the above-mentioned conventional drawbacks and to accurately maintain the opening/closing timing and opening/closing speed between each vacuum valve without increasing the cost. According to the present invention, this object is achieved by the following configuration. That is, a plurality of vacuum valves, an operating mechanism having a spring that applies a predetermined pressure to a movable rod of each vacuum valve to close the vacuum valve, and an operating mechanism that expands and contracts the spring to open and close the vacuum valve. A device comprising an opening/closing mechanism having a cam, and a drive shaft connected to a speed mechanism to be rotated and to which the opening/closing mechanism is attached so as to be able to open and close each vacuum valve in a predetermined order. This is the first cam that opens and closes the vacuum valve by the rotation of the drive shaft of the vacuum valve drive mechanism of the switching device, and the pressing force of the spring is applied to the cam that opens and closes the vacuum valve by the rotation of the drive shaft. Add a protruding cam surface that increases initially.

The structure of the on-load tap changer according to the present invention is the same as that of the conventional one except for a part of the opening/closing device and the vacuum valve operating mechanism as described above.
Hereinafter, the same reference numerals indicate those having the same function as those described above.

FIG. 11 shows a vacuum valve operating mechanism 70 and a switching device 71 according to an embodiment of the present invention, which are energized in parallel with the resistor vacuum valve of the one-resistance, three-vacuum-valve type three-phase load tap changer described above (in FIG. Valve B)
It operates one main vacuum valve. In FIG. 11, the components other than the cam 72 and the pressure spring 73 are the same as those in FIG. 5 described above, so the explanation of the overlapping parts will be omitted. The cam 72 is provided with a cam surface 66 that protrudes onto the outer circumferential circle 65, avoiding the contact position of the cam 62 with the cam roller 61 when the vacuum valve is normally closed. That is, when the cam roller 61 rides on the protruding cam surface 66, the cam roller 61 is pushed up further toward the fixed rod 52 than when the vacuum valve is normally closed. In other words, the pressure spring 73 is further compressed, and in other words, the contact pressure between the fixed rod 52 and the movable rod 53 is further increased. However, this problem can be overcome by selecting the spring constant of the pressure spring 73 to be smaller than the conventional one.

FIG. 12 is an enlarged view of the cam 72, and the drive shaft 6
4(O ₂ ) is the angle θ = φ ₁ + α + β + γ + δ ₁ + δ ₂ +
The vacuum valve opens and closes by reciprocating rotation by _φ2 . The only difference from FIG. 6 is that the cam roller 61 moves on a protruding cam surface 66.

Figures 13 and 13 are torque diagrams depicting the torque of the drive shaft required to open and close the vacuum valve using the cam of the present invention according to the rotation angle of the cam, and the cam rotation angles α, β, γ, δ. ₁ and δ ₂ match the rotation angles shown in FIG. 1 is a diagram of a vacuum valve closing operation, and 2 is a diagram of a vacuum valve opening operation.

The operation of the cam according to the present invention is that in the direction from opening to closing the vacuum valve, the cam 72 moves counterclockwise as shown in FIG. 12, so the rear shaft torque changes from _zero to tripping as shown in FIG. While pressing the spring 58, the movable rod 53 gradually increases, and when it moves by α angle, the movable rod 53
contacts the fixed rod 52. From now on, the pressure spring 73
As the cam 72 enters the pushing stroke, the torque increases rapidly and reaches its maximum torque at the point where the cam 72 moves by an angle β and touches the top of the protruding cam surface 66. Thereafter, the pressure gradually decreases, and after passing through idle rotation at an angle of δ ₁ , the vacuum valve reaches a predetermined normal external pressure at the point where it moves at an angle of δ ₂ , and the torque becomes zero. Thereafter, it rotates with an idle angle of φ ₂ and stops, and the torque diagram of the drive shaft becomes 1 in FIG. 13. If the drive shaft is rotated in the opposite direction from closing to opening the vacuum valve, the operation will be completely opposite to that described above, and the 13th
It will look like Figure 2.

Figures 14 and 15 are torque diagrams when three-phase vacuum valves with similar actions are opened and closed simultaneously as shown in the time chart in Figure 8. The solid line is for one phase, and the dotted line is for three phases. The resultant torque is Figure 14 shows when switching from tap T ₁ to T ₂ directions,
That is, this is when switching from main vacuum valve B to main vacuum valve A, which is energized in parallel with vacuum valve R for current limiting resistor. In this case, the resultant torque is cam 7
Since the protruding cam surface 66 of No. 2 becomes positive at the beginning of switching and acts as a drag, the vacuum valve does not start moving before the torque generated by the tension spring reaches a specified value, unlike in the conventional case. Figure 15 is a torque diagram when switching from tap T ₂ to T ₁ in the direction. In this case, the resultant torque becomes a large resistance from the beginning of switching, and the protruding cam surface 66 acts as a negative torque at the end of switching, so there is no problem. do not have.
In the case of simultaneous three-phase switching, the vacuum valve B of any phase may be opened and closed by the cam 72 of the present invention.

In a three-phase load tap changer using a vacuum valve, the 16th tap switch is used to reduce the composite torque.
As shown in the figure, the opening and closing timing of each vacuum valve may be shifted as much as possible. In this case, if the predetermined tap switching starts with the opening of the main vacuum valve that is energized in parallel with the resistance vacuum valve, the cam 72 of the present invention can be used at least for the main vacuum valve that is opened first, so that the protrusion of the cam 72 can be reduced. The torque exerted by the cam surface 66 acts as a drag force, overcoming the drawbacks of the prior art. In the case of switching opposite to the above, the torque due to the protruding cam surface 66 acts as negative, but there is no problem as in the case of FIG. 15.

Similarly, when the opening and closing timings of the three-phase valves are slightly shifted, the protruding cam surface 66 may be provided on the cam of the vacuum valve B of any phase.

In the above description, a three-phase on-load tap changer was mainly described, but the present invention is not limited to this and can be applied as is to a one-phase or a multi-phase device having two or more phases.

As is clear from the above explanation, in a one-resistance, three-vacuum-valve on-load tap changer that is operated by a speed mechanism, at least one main vacuum valve that is energized in parallel with the resistance vacuum valve is operated during switching. Accurate opening/closing speed and timing of each vacuum valve can be ensured by operating a cam with a protruding cam surface that increases the contact pressure between the fixed rod and the movable rod even more than the normal contact pressure.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the switching order for one phase of a one-resistance, three-vacuum-valve type on-load tap changer, Fig. 2 is an explanatory diagram of the tap switching mechanism, and Figs. 3 and 4 are diagrams of the tap switching operation, respectively. Figure 5 is a structural diagram of the vacuum valve operating mechanism and opening/closing device, Figure 6 is a diagram of the cam and cam roller operation, Figure 7 is a torque diagram of the drive shaft for opening and closing the vacuum valve, and Figure 8 is under three-phase load. Opening/closing chart of the tap changer. Figure 9 is the torque diagram when switching _{in one} direction when three phases are opened and closed simultaneously. Figure 10 is the tap T ₁ → when three phases are opened and closed simultaneously.
T Torque diagram when switching between _two directions; FIG. 11 is a structural diagram of the vacuum valve operating mechanism and opening/closing device according to the embodiment of the present invention; FIG. 12 is a diagram of the cam and cam roller operation of the embodiment of the present invention; FIGS. 13 and 14 Figure, Figure 15,
Fig. 17 is a torque diagram when switching the three-phase load tap changer according to the embodiment of this invention, and Fig. 16 shows the opening/closing of the three-phase load tap changer when the opening/closing timing of each vacuum valve is shifted as much as possible. It's a chat. 2a, 2b: Tap selector, 27: Rapid movement mechanism,
52: fixed rod, 53: movable rod, 64: drive shaft, 66: protruding cam surface, 71: opening/closing device,
73: Pressure spring, A, B: Main vacuum valve,: Vacuum valve for resistance, r = current limiting resistor, T ₁ , T ₂ : Tap,
_O2 : Drive shaft.

Claims (1)

[Claims] 1. A plurality of vacuum valves, an operating mechanism having a spring that applies a predetermined pressure to a movable rod of each vacuum valve to close the vacuum valve, and a cam that expands and contracts the spring to open and close the vacuum valve. and a drive shaft to which the opening and closing mechanism is connected and rotated by a quick-acting mechanism and capable of opening and closing each vacuum valve in a predetermined order. The cam is the first cam that opens and closes the vacuum valve by rotation, and has a protruding cam surface that is added to the cam that opens and closes the vacuum valve and increases the pressing force of the spring at the beginning of rotation of the drive shaft. A vacuum valve operating mechanism for a tap changer on load, characterized by: