JP2003297648A - On-load tap changer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent failure expansion by protecting a winding of a transformer when a vacuum valve used for a change-over switch of an on-load tap changer is abnormal, and warning the outside for the abnormality. <P>SOLUTION: For the change-over switch of the on-load tap changer, 3-position (on-off-on) type vacuum valves 4a and 4b are used. One side fixed contacts 4aL and 4bR of each of vacuum valves 4a and 4b are connected to movable contacts 5a and 5b of a tap selector, respectively, selecting adjacent taps 6a and 6b lead out from a winding 1 of a transformer, with disposing auxiliary switches 3a and 3b therebetween. The other side fixed contacts 4aR and 4bL are connected to the movable contacts 5a and 5b of the tap selector, respectively, selecting the opposite taps of the previously connected taps, with disposing current-limiting resistors therebetween. Movable contact side of each of vacuum valves is connected to a neutral point. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load tap changer.

[0002]

2. Description of the Related Art A prior art load tap changer using a vacuum valve in a changeover switch section has several changeover switch circuit configurations by combining a plurality of vacuum valves and a current limiting resistor and an auxiliary switch. It was The switching switch circuit configurations will be described with reference to the examples shown in FIGS. 7 to 9. The switching switch circuit shown in FIG. 7 has two taps between the movable contacts 5a and 5b of the tap selector that selects one of the adjacent taps 6a and 6b drawn from the transformer winding 1 and the neutral point. It is a switching switch circuit of a 2-resistance 4-valve system in which vacuum valves 4a1, 4a2 or 4b1, 4b2 are connected in series, and current limiting resistors 2a, 2b are connected in parallel with the vacuum valve near the neutral point side. No. 62-16004.

In the switching switch circuit shown in FIG. 8, either one of the movable taps 5a and 5b of the tap selector which selects one of the adjacent taps 6a and 6b drawn from the transformer winding 1 is selected and connected. The changeover switch 3 and a vacuum valve 4a3 for interrupting the load current are connected in series, and the other end of the vacuum valve is connected to the neutral point. Further, one of the adjacent taps 6a and 6b drawn from the transformer winding 1 is connected in series with a current limiting resistor 2 connected to a movable contact 5b of a selected tap selector and a vacuum valve 4a4 for interrupting a circulating current,
Connect the other end of this vacuum valve to the neutral point 1
It is a switching switch circuit of a resistance two-valve system and is No. 26535.
It is introduced in Japanese Patent Publication No. 85.

In the switching switch circuit shown in FIG. 9, between the movable contacts 5a and b5 of the tap selector which selects one of the adjacent taps 6a and 6b drawn from the transformer winding 1 and the neutral point. The vacuum valves 4a5 and 4b5 are connected, and the vacuum valve 4b6 connected in series with the current limiting resistor is connected to the vacuum valve 4b.
5 is a 1-resistance 3-valve switching switch circuit connected in parallel with 5.

[0005]

In recent years, a load tap changer using a vacuum valve in the breaking portion of the changeover switch has been commercialized. This tap changer during load has a merit of improving the breaking performance because the current is cut off by a vacuum valve, and in the oil-insulated transformer, there is a merit that the oil is not polluted and is rapidly spreading.

However, since the breaking performance of the vacuum valve depends on the degree of vacuum in the vacuum valve, the inside of the vacuum valve is damaged due to an abnormality such as damage to the insulating cylinder of the vacuum valve or deterioration of the expansion bellows for moving the vacuum valve movable contact. If the vacuum level decreases, and if you continue to use it in that state, it will not be possible to shut off with a vacuum valve.Depending on the circuit configuration of the switching switch, short circuit between taps or carbon breaks in the auxiliary arc current shutoff arc There was a risk that the insulation performance of each part of the switching switch would deteriorate due to oil pollution.

[0007] Regarding the state when the vacuum valve is abnormal in the switching switch of the conventional tap changer under load, from FIG. 10 to FIG.
This will be described using the example shown in FIG. FIGS. 10A and 10B are circuit diagrams showing the states of the two-resistance four-valve switching switch when each vacuum valve is abnormal. 10A shows a state when the vacuum valve 4a2 is in an abnormal state, and FIG.
Indicates the state when the vacuum valve 4a1 is abnormal. Figure 1
When the vacuum valve shown in 0 (a) is abnormal, tap 6
At the time of completion of switching from a to tap 6b, the tap 6a and tap 6b are continuously short-circuited between taps by a circuit including a vacuum valve 4b2, a vacuum valve 4b1, a current limiting resistor 2a and a vacuum valve 4a2 as shown by a dotted line in the figure. However, the current limiting resistor 2a burns out to eliminate the short-circuit condition and protects the transformer winding 1. At the same time, the pressure rise due to the current limiting resistor burning out is detected by a protective relay, etc. Can be prevented from expanding. Vacuum valve 4
The same phenomenon occurs when b2 is abnormal.

However, when the vacuum valve shown in FIG. 10B is abnormal, the vacuum valve 4b2, the current limiting resistor 2b, and the vacuum valve 4a1 are indicated by the dotted line in the process of switching from the tap 6a to the tap 6b. The circuit including the vacuum valve 4a2 and the vacuum valve 4a2 disables the current limiting resistor 2a that limits the circulating current, so that the circulating current is higher than in the normal state.
And tap 6b, and vacuum valve 4a2
Since there is a large amount of breaking current, the contact wear of the vacuum valve may be affected, and the transformer winding 1 may be damaged. When the vacuum valve 4a1 is abnormal, the short circuit between taps does not continue and the current limiting resistance does not burn out, so that the abnormality cannot be externally warned. Therefore, the vacuum valve 4a
If 1 is used in an abnormal state and the vacuum valve 4a2 is in an abnormal state, the tap 6a and the tap 6b are completely short-circuited as shown by the dotted line in FIG. 10 (c), and the transformer winding 1 is damaged. To do. The same phenomenon occurs when the vacuum valve 4b1 is abnormal.

FIGS. 11 (a) and 11 (b) are circuit diagrams showing the states of the one-resistance two-valve switching switch when each vacuum valve is abnormal. 11A shows a state where the vacuum valve 4a4 is in an abnormal state, and FIG. 11B shows the vacuum valve 4a3.
Indicates an abnormal state. In the case of the vacuum valve abnormality shown in FIG. 11A, the current limiting resistor 2 and the vacuum valve 4a4 are provided between the taps 6a and 6b at the end of the switching from the tap 6b to the tap 6a as shown by the dotted line in the figure. A short circuit between taps continues due to the circuit consisting of the vacuum valve 4a3 and the auxiliary switch 3, but the current limiting resistor 2 burns out to eliminate the short circuit state, protects the transformer winding 1, and protects the pressure due to the current limiting resistance burning out. The rise of the fault can be prevented by detecting the rise by a protective relay and alarming the abnormality to the outside.

However, when the vacuum valve shown in FIG. 11 (b) is abnormal, the vacuum valve 4a3 is assisted in an abnormal (closed) state as shown by the dotted line in the process of switching from the tap 6a to the tap 6b. Since the switch operates, the auxiliary switch, which normally operates in the no-load state, operates in the loaded state and interrupts the current, so that a breaking arc 9 is generated, and the arc causes the oil to contaminate the switching switch parts. There was a risk that the insulation performance would deteriorate. Further, since the short circuit between taps does not continue and the current limiting resistor 2 does not burn out, it is not possible to externally warn of an abnormality, and continuous use in this abnormal state may lead to a problem expansion due to deterioration of the inter-electrode and inter-phase insulation.

FIGS. 12 (a) and 12 (b) are circuit diagrams showing the states of the one-resistance three-valve switching switch when each vacuum valve is abnormal. 12A shows a state when the vacuum valve 4b6 is in an abnormal state, and FIG. 12B shows the vacuum valve 4b5.
Indicates an abnormal state. In the case where the vacuum valve shown in FIG. 12A is abnormal, the current limiting resistor 2 and the vacuum valve 4b6 are provided between the taps 6a and 6b at the end of the switching from the tap 6b to the tap 6a as shown by the dotted line in the figure. A short circuit continues between taps by a circuit consisting of a vacuum valve 4a5 and a vacuum valve 4a5. However, the current limiting resistor 2 burns out to eliminate the short circuit state, protects the transformer winding 1, and protects the pressure rise due to current limiting resistance burning out. For example, it is possible to prevent the problem from spreading by detecting it with an alarm and alerting the abnormality to the outside.

However, in the case where the vacuum valve shown in FIG. 12B is abnormal, the vacuum valve 4b5 is provided between the taps 6a and 6b at the end of the switching from the tap 6a to the tap 6b as shown by the dotted line in the figure. The circuit including the vacuum valve 4a5 causes a complete short circuit and damages the transformer winding 1. The same phenomenon occurs when the vacuum valve 4a5 is abnormal.

As described above, in the conventional switching switch of the load tap changer, when the vacuum valve is abnormal, there is a possibility that the vacuum valve abnormality cannot be detected depending on the part of the vacuum valve, and the defect may spread. .

In view of the above, the present invention has a problem in a load tap changer using a vacuum valve as a changeover switch, by detecting an abnormality when the vacuum valve at each part used in the changeover switch is abnormal and issuing an alarm to the outside. It is an object of the present invention to provide a tap changer under load equipped with a changeover switch capable of preventing the expansion of the tap.

[0016]

In order to solve the above-mentioned problems, the present invention constitutes a switching switch of a tap switch during load by the following means. The invention corresponding to claim 1 is a load tap changer having a change-over switch that cuts off a transformer load current and performs tap changeover, wherein a three-position (on-off-on) type vacuum valve is provided in the changeover switch. Use two pieces for each phase, connect one fixed contact of each vacuum valve through the auxiliary switch to one of the adjacent taps drawn from the winding of the transformer to the movable contact of the selected tap selector, and connect the other By connecting the fixed contact to the movable contact of the selected tap selector, which is the opposite of the tap previously connected via the current limiting resistor, and connecting the movable contact side of each vacuum valve to the neutral point, When the vacuum valve of each part is abnormal, a short circuit occurs between the taps via the current limiting resistance, and the pressure resistor winding is protected by the burning of the current limiting resistance, and the pressure rise due to the current limiting resistance burning is detected by a protective relay or the like. Abnormalities outside It is intended to prevent the spread of trouble by warning.

According to a second aspect of the present invention, in a load tap changer having a changeover switch that cuts off a transformer load current to perform tap changeover, the changeover switch has three positions (ON-OFF-
ON) type vacuum valve is used for each phase, and one fixed contact of this vacuum valve is a movable contact of the tap selector that selects one of the adjacent taps drawn from the transformer winding through the protective fuse. To the movable contact of the selected tap selector, and connect the other fixed contact to the movable contact of the selected tap selector with the opposite tap from the one connected earlier via the current limiting resistance. By connecting to the point, when the vacuum valve of each part is abnormal, short-circuiting occurs between the taps through the current limiting resistance or the protective fuse, and the current limiting resistance or the protective fuse burns out to protect the pressure winding. Protective relays are used to detect pressure rises due to current limiting resistance or protective fuse burnout, and alarms to the outside to prevent the spread of defects.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 shows an embodiment of a switching switch circuit of a load tap changer according to the present invention, FIG. 3 shows another embodiment of a switching switch circuit of a load tap changer according to the present invention, and FIGS. Reference numeral 4 denotes the switching operation of the switching switch circuit of the tap changer during load according to the present invention shown in FIGS.

In the embodiment of the present invention shown in FIG. 1, the movable contacts 5a and 5b of the tap selector for selecting the adjacent taps 6a and 6b drawn from the transformer winding 1. A current limiting resistor 2a, 2b for limiting the circulating current in the tap switching process and a 3-position (on-off-on) type vacuum valve 4 for interrupting the current.
a and 4b, and auxiliary switches 3a and 3b for alternately connecting the vacuum valve and the movable contacts 5a and 5b of the tap selector.

Adjacent taps 6a drawn from the transformer winding 1 through auxiliary switches 3a and 3b to one fixed contact 4aL and 4bR of each three-position (on-off-on) type vacuum valve 4a and 4b. 6b is connected to the movable contact 5a or 5b of the tap selector, and the other fixed contact 4
The aR and 4bL are connected to the movable contact 5a or 5b of the tap selector selected from the tap opposite to the one previously connected through the current limiting resistors 2a and 2b, and the movable contact side of each vacuum valve is neutral. Connect to a point.

The switching operation of the embodiment shown in FIG. 1 will be described with reference to FIGS. The state (a) shows the operating state in which the contact 4aL of the vacuum valve 4a and the auxiliary contact 3a are closed and is connected to the tap 6a, and the load current IL flows to the tap 6a as shown by the dotted line in the figure. (B)
In this state, the switching operation is started and the contact 4 of the vacuum valve 4a is
The load current IL flows from the contact point 4bL of the vacuum valve 4b to the tap 6a via the current limiting resistor 2b. The state (c) shows a state in which the contact 4aR of the vacuum valve 4a is closed, and the contact 4aR of the vacuum valve 4a, the contact 4bL of the vacuum valve 4b, and the current limiting resistors 2a and 2b are used to connect the taps 6a and 6b. A short circuit open circuit is formed between them, and the circulating current IC limited by the current limiting resistors 2a and 2b flows. The state (d) shows a state in which the unloaded auxiliary switches 3a and 3b are operated, and the circulating current IC continues to flow. The state (e) shows a state in which the contact 4bL of the vacuum valve 4b is opened, and the load current IL flows from the contact 4aR of the vacuum valve 4a to the current limiting resistance 2
It flows to tap 6b via a. The state (f) shows a state in which the contact 4bR of the vacuum valve 4b is closed, and the load current IL flows to the tap 6b as shown by the dotted line in the figure, and the switching operation is completed.

The state when the vacuum valve is abnormal in the embodiment shown in FIG. 1 will be described with reference to FIGS. 5 (a) and 5 (b). 5A shows a state when the vacuum valve 4a is in an abnormal state, and FIG. 5B shows a state when the vacuum valve 4b is in an abnormal state. In the case of the vacuum valve abnormality shown in FIG. 5A, the current limiting resistor 2a and the vacuum valve 4a are provided between the taps 6a and 6b at the end of the switching from the tap 6b to the tap 6a as shown by the dotted line in the figure. A short circuit between taps continues due to the circuit consisting of the auxiliary switch 3a and the current limiting resistor 2a, which eliminates the short circuit condition and protects the transformer winding 1, and protects the pressure rise due to the current limiting resistance burning. For example, it is possible to prevent the problem from spreading by detecting it with an alarm and alerting the abnormality to the outside.

In the case of an abnormal vacuum valve shown in FIG. 5B, at the time when the switching from the tap 6a to the tap 6b is completed, a current limiting resistor 2b is formed between the taps 6a and 6b as shown by a dotted line in the figure. The circuit consisting of the vacuum valve 4b and the auxiliary switch 3b causes a short circuit between taps to continue, but the current limiting resistor 2b burns out to eliminate the short circuit condition, protects the transformer winding 1, and increases pressure due to current limiting resistance burning. It is possible to prevent the problem from spreading by detecting the alarm with a protective relay and alarming the abnormality to the outside.

Further, even if the vacuum valves 4a and 4b in FIG. 1 become abnormal at the same time, since one of the auxiliary switches 3a and 3b is in the open state, the tap 6a and the tap 6 are tapped.
5 (a) and 5 (b) without being completely short-circuited between b, the current limiting resistor 2a or 2b is burned out to eliminate the short-circuited state, protect the transformer winding 1, and It is possible to prevent the failure from spreading by detecting the pressure rise due to the flow resistance burnout with a protective relay and alarming the abnormality to the outside.

In the embodiment of the present invention shown in FIG. 3, the movable contacts 5a and 5b of the tap selector for selecting the adjacent taps 6a and 6b drawn from the transformer winding 1. A current limiting resistor 2a, 2b for limiting the circulating current in the tap switching process and a 3-position (on-off-on) type vacuum valve 4 for interrupting the current.
a, 4b and between the vacuum valve and the movable contacts 5a, 5b of the tap selector to prevent the transformer winding 1 from overcurrent.
It is composed of protective fuses 7a and 7b for protecting the.

Adjacent taps 6a drawn from the transformer winding 1 through protective fuses 7a and 7b to one fixed contact 4aL and 4bR of each vacuum valve 4a and 4b of three-position (on-off-on) type, 6b is connected to the movable contact 5a or 5b of the tap selector, and the other fixed contact 4
The aR and 4bL are connected to the movable contact 5a or 5b of the tap selector selected from the tap opposite to the one previously connected through the current limiting resistors 2a and 2b, and the movable contact side of each vacuum valve is neutral. Connect to a point.

The switching operation of the embodiment shown in FIG. 3 will be described with reference to FIGS. The state (a) shows the operating state in which the contact point 4aL of the vacuum valve 4a is closed and is connected to the tap 6a, and the load current IL flows to the tap 6a as indicated by the dotted line in the figure. The state (b) shows a state in which the switching operation is started and the contact 4aL of the vacuum valve 4a is opened, and the load current IL flows from the contact 4bL of the vacuum valve 4b to the tap 6a via the current limiting resistor 2b. The state (c) shows a state in which the contact 4aR of the vacuum valve 4a is closed, and the contact 4aR of the vacuum valve 4a, the contact 4bL of the vacuum valve 4b and the current limiting resistors 2a, 2b.
A short circuit open circuit is formed between the taps 6a and 6b, and the circulating current IC limited by the current limiting resistors 2a and 2b flows. The state (d) shows a state in which the contact 4bL of the vacuum valve 4b is opened, and the load current IL flows from the contact 4aR of the vacuum valve 4a to the tap 6b via the current limiting resistor 2a. The state (e) shows a state in which the contact 4bR of the vacuum valve 4b is closed, and the load current IL flows to the tap 6b as shown by the dotted line in the figure, and the switching operation is completed.

The state when the vacuum valve is abnormal in the embodiment shown in FIG. 3 will be described with reference to FIGS. 6 (a) and 6 (b). 6A shows a state when the vacuum valve 4a is abnormal, and FIG. 6B shows a state when the vacuum valve 4b is abnormal. In the case of the vacuum valve abnormality shown in FIG. 6A, the current limiting resistor 2a and the vacuum valve 4a are provided between the taps 6a and 6b at the end of the switching from the tap 6b to the tap 6a as shown by the dotted line in the figure. A short circuit between taps continues due to the circuit consisting of the protection fuse 7a and the current limiting resistor 2a burns out to eliminate the short circuit condition, protects the transformer winding 1, and protects the pressure rise due to current limiting resistance burning. For example, it is possible to prevent the problem from spreading by detecting it with an alarm and alerting the abnormality to the outside.

When the vacuum valve is abnormal as shown in FIG. 6B, at the time when the switching from the tap 6a to the tap 6b is completed, the current limiting resistance 2b is provided between the taps 6a and 6b as shown by the dotted line in the figure. A short circuit between taps continues due to the circuit consisting of the vacuum valve 4b and the protective fuse 7b, but the current limiting resistor 2b burns out to eliminate the short circuit state, protects the transformer winding 1, and increases the pressure due to current limiting resistance burning. It is possible to prevent the problem from spreading by detecting the alarm with a protective relay and alarming the abnormality to the outside.

Even if the vacuum valves 4a and 4b in FIG. 3 become abnormal at the same time, one of the protective fuses 7a and 7b is instantly blown by the short-circuit current and the tap 6
Protect the short circuit winding 1 without a continuous short-circuit between a and tap 6b, and prevent a fault from spreading by detecting an increase in pressure due to protective fuse blowout with a protective relay and alerting the abnormality to the outside. You can

[0031]

According to the present invention, even if the vacuum valve in each part of the switching switch is in an abnormal state, a complete short circuit between the taps is prevented, the transformer winding is protected, and an alarm is given to the outside. By doing so, it is possible to prevent the problem from expanding.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a tap changer under load showing an embodiment of the present invention.

FIG. 2 is a circuit diagram sequentially showing the switching operation of the embodiment shown in FIG. 1 from (a) to (f).

FIG. 3 is a circuit diagram of a tap changer under load showing another embodiment of the present invention.

FIG. 4 is a circuit diagram sequentially showing the switching operation of the embodiment shown in FIG. 3 from (a) to (e).

5 is a circuit diagram showing a state when the vacuum valve is abnormal in the embodiment shown in FIG.

6 is a circuit diagram showing a state when the vacuum valve is abnormal in the embodiment shown in FIG.

FIG. 7 is a circuit diagram of a 2-resistor 4-valve type switching switch in a conventional tap changer during load.

FIG. 8 is a circuit diagram of a one-resistance two-valve type switching switch in a conventional load tap switching device.

FIG. 9 is a circuit diagram of a one-resistance three-valve type switching switch in a conventional load tap switching device.

10 is a circuit diagram showing a state when the vacuum valve is abnormal in the conventional load tap changer shown in FIG.

FIG. 11 is a circuit diagram showing a state when the vacuum valve is abnormal in the conventional load tap changer shown in FIG.

FIG. 12 is a circuit diagram showing a state when the vacuum valve is abnormal in the conventional load tap changer shown in FIG.

[Explanation of symbols]

1 transformer winding 2a, 2b current limiting resistance 3a, 3b auxiliary switch 4a, 4b vacuum valve 6a, 6b tap 7a, 7b protection fuse

Claims (2)

[Claims] Claim: What is claimed is: 1. A load tap changer having a change-over switch that cuts off a transformer load current and performs tap changeover. In the change-over switch, a 3-position (on-off-on) type vacuum valve is provided for each phase. Connect one of the adjacent taps drawn from the transformer winding through the auxiliary switch to one fixed contact of each vacuum valve to the movable contact of the selected tap selector, and connect the other fixed contact to the fixed contact. At the time of load characterized by connecting the tap opposite to the one previously connected via the current limiting resistance to the movable contact of the selected tap selector and connecting the movable contact of each vacuum valve to the neutral point. Tap changer. 2. A load tap changer having a change-over switch that cuts off a transformer load current and performs tap changeover, wherein the change-over switch has three 3-position (on-off-on) type vacuum valves for each phase. Connect one of the adjacent taps drawn from the transformer winding through the protective fuse to one fixed contact of this vacuum valve to the movable contact of the selected tap selector, and connect the other fixed contact to the fixed contact. At the time of load characterized by connecting the tap opposite to the one previously connected via the current limiting resistance to the movable contact of the selected tap selector and connecting the movable contact of each vacuum valve to the neutral point. Tap changer.