JPS5939891B2 - On-load tap changer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an on-load tap changer that uses a vacuum valve as a current switching element and is equipped with a disconnect switch that protects the vacuum valve from intrusion surges while the vacuum valve is open.

Generally, the stroke of a vacuum valve is often kept as small as possible to ensure the mechanical life of the vacuum valve. As a result, the withstand voltage between the electrodes of the vacuum valve decreases, and lightning surges, etc. enter the tap changer section during load during transformer operation, causing a flash between the electrodes of the vacuum valve and a short circuit between the taps, resulting in a serious accident. There is a risk that this will develop. As a countermeasure against this, a disconnect switch with a high withstand voltage is provided between the tap selector and the vacuum valve to protect it. It is desirable for this type of switch to have a simple drive mechanism, to be configured with three phases all at once, and to be compact. As an example of a load tap changer equipped with this type of disconnect switch,
No. 1050 is known.

In this disclosed technology, both poles of an open vacuum valve are short-circuited by a part of a switching switch, and for this purpose, five stationary contacts per valve are arranged all around the circumference. Ru. Therefore, when applied to a three-phase converter, it is necessary to arrange the five fixed contact groups in three stages, which increases the length of the device in the vertical direction, which is undesirable because the overall length of the tap changer during load increases. . In addition, by applying this invention, a total of 15
It is also not preferable to arrange the fixed contacts on the circumference in the same plane because the device becomes very large in the radial direction. It is an object of the present invention to eliminate the above-mentioned drawbacks and provide a compact and mechanically simple on-load tap changer with a disconnect switch that is integrated into three phases.

In order to achieve this object, according to the configuration of the present invention, the contacts for each of the three phases of the disconnection switch are arranged in two stages, and among these, the fixed contact for connecting the neutral point is arranged in one stage in each of the adjacent phases. The contacts were made for industrial use and the three phases were formed into a compact size. Figures 1 to 9C
The drawings show embodiments of the present invention, which will be described below with reference to the drawings.

In FIG. 1, a drive shaft 1 is connected to a driving mechanism (not shown), and is connected to a swing shaft 4 of a disconnection switch 3 via an intermittent swing drive mechanism 2, causing it to swing intermittently. The intermittent swing drive mechanism 2 is provided with a groove 210 as shown in FIG.
Moreover, the cam disk 202 is fixed to the drive shaft 1, and the swing lever is fixed to the swing shaft 4 and has a pin 203 fixed to its tip that fits into a groove 210 provided in the cam disk 202.
It consists of 204. The groove 210 provided in the cam disk 202 is formed as follows. On the A side above the diameter E of the cam disk 202, at a position of radius R1 from the center 0, there is an area θ3 in the clockwise direction, that is, between the angle E-0 and the opening, and an area θ12, that is, the angle E- Pin 20 between 0 and Nu
A groove 211 is provided at a position with a radius R1 that conforms to 3, and a groove 211 is provided at a position with a radius R2 between the area θ5 (angle 0-2) and the area θ,o (angle 0-2). Groove 212 and area θ
7 and θ8, that is, a groove 213 provided at a radius R3 between the angles 0 and 5, and a groove 211 provided at a radius R1.
and a groove 212 provided at a radius R2.
A groove 210 is formed by arranging a groove 212 provided at a radius R2 and a groove 215 connecting a groove 213 provided at a radius R3 in an endless circle having different diameters as shown in FIG. be done.

The movement of the intermittent rocking 1 drive mechanism 2 will be explained with reference to FIG.

FIG. 2 shows the normal stop state, and the groove 210 can be opened with one tap.
When it rotates 80 degrees and reaches the position A in Figure 2, it becomes the other normal stop position. When tap switching starts and the cam disk 202 rotates, for example, in the direction of the arrow, the pin 203 remains fixed at the "l" position until the mouth reaches the "a" position, so the swing lever 204 rotates. Swing axis 4
becomes stationary and the disconnect switch 3 is not driven. While the cam disk 202 rotates further until C reaches the position A, the pin 203 moves along the groove 214 and is displaced to the position "■".As a result, the swing shaft 4 rotates by θ1. Then, the disconnect switch 3 is driven 5. Similarly, when the cam disk 202 rotates further, the swing shaft 4 remains stationary until the position D reaches the position A, and the pin 203 remains stationary until the position H reaches the position A. but"
The pivot shaft 4 rotates by θ2 upon reaching the position "I", and by the time it reaches the "I" position, the pivot shaft 4 comes to a stationary state again and stops, completing the tap switching. Here θ3-θ7-θ8θ
12 pieces θ4': θ6: θ9 = θ11? θ5 = θ10) and radius R1, R2, R3 so that θ, -θ2.
If this is determined, the disconnect switch will move symmetrically in response to the tap switching operation, and the pin 203 will always be in the "
I] → "■" → "■" → "■" → "I" → "■] →...
·, and the swing shaft 4 rotates accordingly. In this way, a reversible intermittent swing drive mechanism 2 can be obtained even with a simple swing lever mechanism. Returning to the explanation of the other disconnection switches shown in FIG. They are arranged in the order of 5, 6, 9, 10, 7, and 8 in the counterclockwise direction and are operated in response to the intermittent movement of the swing shaft 4.

The movable contacts 5 to 10 are integrated into two upper and lower blades 1.
3 and 14, and the upper blade 13 is connected to the fixed contacts 16 to 21 (arranged in the 3rd B (shown in the figure), and the lower blade 14 is connected to the fixed contacts 22 to 30 arranged on the other stage (lower stage) (the arrangement is the third
(shown in Figure C). Fixed contacts 16 to 3 on both stages
0 is attached to an insulating column 32 fixed to a frame 31. The drive shaft 1 further includes a vacuum valve drive mechanism 33.
By driving the switch, the movable rods 43 of the vacuum valves 34-42 constituting the switching switch are moved up and down, thereby opening and closing the contacts of the vacuum valves 34-42. Vacuum valve 34-4
The second fixed rod 44 is fixed to an insulating plate 45 fixed to a frame (not shown), and is connected to one stage of fixed contacts 16 to 21 or current limiting impedance elements 47 to 49, or fixed contact 16 via leads 46. 21 and current limiting impedance elements 47 to 49. FIG. 3A shows a schematic arrangement of the vacuum valve 42 as seen in cross section BB in FIG. In FIG. 3A, the contacts of the vacuum valves 34 to 42 are actually located at the back in the direction perpendicular to the plane of the paper, a movable contact (one contact) fixed to the movable rod 43, and at the front, the movable contact (one contact) is fixed to the fixed rod 44. Although a fixed fixed contact (the other contact) is arranged, both contacts are shown on the same plane as the drawing for ease of understanding. In FIG. 3A, vacuum valves 34-3
6 is for the U phase, 37 to 39 are for the V phase, and 40 to 42 are for the W phase, and the movable rods 43 to which one contact of each vacuum valve is conductively connected are all connected to the neutral point via the flexible lead 50. On the other hand, the fixed rod 44 to which the other contact of the vacuum valve is conductively connected is connected to one end of the fixed contacts 16 to 21 or the current limiting impedance elements 47 to 49, or the fixed contact as shown in the figure. 16-21 and the other ends of current-limiting impedance elements 47-49.
FIG. 3B is a sectional view taken along the line CC in FIG. 1, showing the arrangement of the fixed contacts 16 to 21 in one stage. In Fig. 3B, fixed contacts 16 and 17 are for U phase, 18 and 19 are for phase, and 20
, 21 are for the W phase, and these contacts are arranged counterclockwise at intervals of 16, 17, 20, 21, 1 on the same circumference.
They are arranged in the order of numbers 8 and 19 and are connected as shown in the figure. FIG. 3C is a sectional view taken along the line DD in FIG. 1 and shows the arrangement of the fixed contacts 22 to 30 in the other stage. In Fig. 3C, a pair of fixed contacts 22 and 23 are for each phase, 24 and 25 are for the V phase, and 26 and 27 are for the W phase, and these contacts are spaced apart from each other on the same circumference. 22, 23, 3 counterclockwise.
They are arranged in the order of 0, 26, 27, 29, 24, 25, and 28, and the 17 side end of the fixed contact 16 and the 23 side end of the fixed contact 22 are at the same position in a plane. As a typical example, the connection for the U phase is such that the fixed contact 22 is connected to the movable contact 52 of a tap selector that selects odd numbered taps Ul, U3, U5, etc. provided on the U phase tap winding 51. , fixed contact 23
are even-numbered taps U2, U4, and U6 of the U-phase tap winding 51.
It is connected to the movable contact 53 of the tap selector that selects the V-phase, W-phase fixed contacts 24, 25, 26.
, 27, each tap winding 54, 55 is based on the same idea.
are connected to contacts 56, 57, 58, and 59 for selecting each tap. Fixed contact 28 is used for both U phase and V phase, 2
9 is the neutral point N that can be used for both the V phase and W phase, and 30 is the neutral point N that can be used for both the U phase and W phase.
All of these three fixed contacts are disposed between adjacent phases, and each is connected to the neutral point N by a neutral point lead 60. Next, the tap switching process according to the present invention will be explained with reference to the drawings, taking the U phase as a representative example.

3A, 3B, 3C, and each figure show the energization state at tap U3, and the current is from tap U3 → movable contact 52 →
Fixed contact 22 → Movable contact 5 → Fixed contact 16 → Lead 4 → Vacuum valve fixed rod 44 → Movable rod 43
→Deflection lead 50 →Flows like neutral point N. At this time, the movable contact 43 and the fixed contact 44 of the vacuum valves 35 and 36 in the open state are connected by the flexible lead 50, and the lead 46, the fixed contact 17, the movable contact 6, the fixed contact 30, and the neutral Both contacts are connected to the neutral point N by a point lead 60, and both contacts of each open vacuum valve are brought to the same potential. Tap U2-U3
The voltage between them is handled by the gap between the fixed contacts 23 and 30 of the disconnect switch 3, which is the minimum electrode distance (the fixed contacts 22 and 30 are at the same potential). Then, the gap length between both fixed contacts 23 and 30 of the disconnect switch 3 is set to a sufficient length to increase the withstand voltage characteristics, and the disconnect switch with high withstand voltage characteristics is normally in charge of the inter-electrode voltage. It is possible to protect the gap between the poles of a vacuum valve with poor characteristics from false arc short circuits caused by surges that enter the windings or the like. When rotational driving force is applied to the drive shaft 1 and tap switching begins, the movable part of the disconnection switch 3 is first rotated in the direction of the arrow in FIGS. 3B and 3C by the intermittent swing drive mechanism 2. The movable contact 6 of the disconnect switch 3 is separated from the fixed contact 30 and then inserted into the fixed contact 23, as shown in FIGS. 4B and 4.
Stop at the position shown in figure C.

Next, before opening and closing the vacuum valves 35 and 36, the U-phase tap selector 53 shown in FIG. 4C moves in the direction of the arrow to select the next tap U4 without current, and stops at the position shown in FIG. 5C.

Next, the energy stored in the vacuum valve drive mechanism 33 is released to open and close the vacuum valve, but first the vacuum valve 36 is opened (Fig. 6A), and the circulating current is tapped from U3 to the movable contact. 52 → Fixed contact 22 → Movable contact 5 → Fixed contact 16 → Lead 46 → Fixed rod 44 of vacuum valve 34 → Movable rod 43 → Vacuum valve 36 → Current limiting impedance element 47 → Lead 46 → Fixed contact 1
7 → Movable contact 6 → Fixed contact 23 → Movable contact 53 →
Flows from tap U4 to tap U3 (Fig. 6A, 6B,
(See Figure 6C). Next, the vacuum valve 34 is opened (7A
(See figure) The load current and circulating current are interrupted, and the load current is changed to tap U4 → Movable contact 53 → Fixed contact 23 → Movable contact 6 → Fixed contact 17 → Lead 46 → Current limiting impedance element 47 → Vacuum Flows from valve 36 to neutral point (7th A
(See Figures 7B and 7C).

Next, the vacuum valve 35 is closed (see Figure 8A), and the load current changes from tap U4 → movable contact 53 → fixed contact 23 → movable contact 6 → fixed contact 17 → lead 46 → vacuum valve 35 → It flows to the neutral point N (see Figures 8A, 8B, and 8C). This completes the opening and closing of the vacuum valve, and finally the 8th B
8C, the movable part of the disconnection switch 3 is rotated again in the direction of the arrow by the intermittent rocking drive mechanism 2, and the movable contact 5 is fixed to conductively connect the fixed contacts of one stage and the other stage. After being separated from the contactor 22, it is inserted into the fixed contactor 28 and paused at the positions shown in FIGS. 9B and 9C, completing tap switching.

In this state, the voltage applied between both taps U3 and U4 is received by the gap between the fixed contacts 22 and 28 (fixed contacts 23 and 28 are at the same potential), which have high withstand voltage characteristics, and the vacuum valve 3
Since both the movable rod 43 and the fixed rod 44 of No. 4 are connected to a neutral point and have the same potential, the gap between the electrodes of the vacuum valve 34 can be protected from arc short circuit due to sudden surge. As described above, the contacts for each of the three phases of the disconnect switch are arranged in one stage and the other stage, for example, in two stages, upper and lower, and are driven by a simple reversible intermittent rocking drive mechanism. , a compact three-phase disconnect switch can be obtained. As is clear from the above explanation, in a star-connected three-phase load tap changer that uses a vacuum valve with one contact connected to the neutral point as a changeover switch, the drive shaft of the changeover switch A disconnect switch is provided which is driven via an engaged intermittent swing drive mechanism or the like, and has two stages of fixed contacts, one stage having the other contact ( A pair of fixed contacts for each column connected to the stationary contacts (fixed contacts) are arranged at intervals, and a pair of fixed contacts for each column is arranged at intervals on the other stage, and the pair of fixed contacts The contacts are connected to the odd-numbered taps and the even-numbered taps through tap selectors, respectively, and the other stage further includes three contacts arranged between adjacent phases of the pair of fixed contacts and connected to the neutral point, respectively. A fixed contactor is provided, and a pair of movable contacts are provided for each stage to conductively connect the fixed contacts of both stages, and a neutral point potential is applied between the two poles of the opened vacuum valve. By configuring the present invention in such a manner, a three-phase disconnect switch having a simple structure and a small size can be obtained, and therefore a compact on-load tap changer with a three-phase disconnect switch can be obtained and the object can be achieved.

[Brief explanation of drawings]

FIG. 1 is a partial vertical sectional view of a load tap changer according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG.
Figure A is a schematic development view taken along the line B-B in Figure 1, and Figures 3B and 3C are sectional views taken along the line C-C and D- in Figure 1, respectively.
D arrow sectional view, Fig. 4A, Fig. 4B, Fig. 4C, Fig. 5A,
Figure 5B, Figure 5C, Figure 6A, Figure 6B, Figure 6C, Figure 7A, Figure 7B, Figure 7C, Figure 8A, Figure 8B, Figure 8C, Figure 9A.
Figures 9B and 9C are Figures 3A, 3B, and 3, respectively.
It is a state explanatory diagram corresponding to diagram C. 1: 1 drive shaft, 2: intermittent swing drive mechanism, 3: disconnection switch, 4: swing shaft, 5-10: movable contact, 16-30:
Fixed contact, 34-42: Vacuum valve, 47-49: Current-limiting impedance element, 51, 54, 55: Tap winding, 52, 53, 56, 57, 58, 59: Movable contact of tap selector, 202: Cam disc, 203: Pin, Ul
,U3,...Vl,V3,...Wl,
W3...: odd number tap, U2, U4,...
...2, 4, ... W2, W4 ......: Even number tap, N: Neutral point.

Claims (1)

[Claims] 1. A switching switch having, in each phase, a vacuum valve for odd-numbered taps, a vacuum valve for even-numbered taps, and a vacuum valve for current-limiting impedance elements, each of which has one contactor connected to a neutral point;
And in a three-phase on-load tap changer equipped with a tap selector that selectively connects this changeover switch and odd-numbered taps and even-numbered taps of each phase, each stage is provided with a different true cloud valve. A corresponding pair of fixed contacts connected to the other contact, a corresponding pair of fixed contacts provided in the other stage and connected to the odd-numbered taps and even-numbered taps of each phase, respectively, and the other stage. three fixed contacts disposed between adjacent phases of the pair of fixed contacts, each connected to a neutral point, and selectively connecting the other contact of the vacuum valve of the adjacent phase to the neutral point; , a contact that connects the fixed contact of one stage to which the other contact of the closed vacuum valve is connected and the fixed contact of the other stage connected to the tap, and the other of the vacuum valve that is opened. A disconnect switch consisting of a pair of movable contacts, each consisting of a contact that connects the fixed contact of one stage connected to the contact and the fixed contact of the other stage connected to the neutral point. An on-load tap changer characterized by: 2. A switching switch having a vacuum valve for odd-numbered taps, a vacuum valve for even-numbered taps, and a vacuum valve for current-limiting impedance elements in each phase, each of which has one contactor connected to the neutral point,
In a three-phase on-load tap changer provided with this switching switch, a tap selector that selectively connects the odd-numbered taps and even-numbered taps of each phase, and a drive shaft that drives the switching switch and the tap selector. , a pair of fixed contacts provided on one stage and connected to the other contacts of different vacuum valves, and a pair of fixed contacts provided on the other stage and connected to odd-numbered taps and even-numbered taps of each phase, respectively. a pair of fixed contacts corresponding to the same stage, and a pair of fixed contacts in the other stage, each of which is arranged between adjacent phases of the pair of fixed contacts in the other stage and contacted with a neutral point, and selectively connects the other contact of the vacuum valve of the adjacent phase. Three fixed contacts alternately connected to the neutral point, a fixed contact in one stage connected to the other contact of the closed vacuum valve, and a fixed contact in the other stage connected to the tap. and a fixed contact of one stage connected to the other contact of the opened vacuum valve and a fixed contact of the other stage connected to the neutral point. a pair of movable contacts, a swing shaft for causing the movable contacts to swing intermittently, and a cam disc having an endless circular groove with a different diameter on one surface and rotating together with the drive shaft; A tap changer on load, comprising: a pin that engages with a groove of the cam disc and is displaced; and a swing lever that swings and rotates the swing shaft in response to the displacement of the pin.