JPH043094B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a power distribution device with a built-in arrester, and particularly to one having a configuration that simplifies testing work. A conventional power distribution device with a built-in arrester has the configuration shown in FIG. Figure 1 shows an example of a single-phase transformer with a built-in arrester.The high-voltage winding 1 and the high-voltage bushing 2 are connected by a lead wire 3, and ground wires 6 branch out from the middle of the lead wire 3 to open and close them. It is grounded to the tank inner wall 7 via the arrester 4 and the arrester 5. 8 is a ground wire. Further, the low voltage winding 10 is connected to the low voltage bushing 9. In such a configuration, the arrester 5 has two branch circuits because it is a single-phase transformer, but in the case of a three-phase transformer, three branch circuits are required. When conducting a commercial frequency withstand voltage test (referred to as a withstand voltage test) and an induced withstand voltage test (referred to as an induction test) to such a transformer with a built-in arrester, these test voltages are higher than the operation start voltage of the arrester 5, so
During the test, a situation has arisen in which the arrester 5 is activated and a charging current flows. For example, if the peak value of the test voltage is 6KV, the voltage values shown in the following table will occur.

[Table] For this reason, the test is conducted with the switch 4 open, or the arrester 5 is removed if the structure is not equipped with a switch. Therefore, it becomes necessary to operate multiple switches 4 in the tank,
A drawback arises in that it takes a long time to remove the arrester 5. Further, the structure in which the switch 4 is added to each phase branch leads to an increase in the size of the tank. In view of the above drawbacks, the present invention aims to provide a power distribution device with a built-in arrester that simplifies the operation of the switch and reduces the size of the tank. The basic idea of the present invention to achieve such an object is to commonly connect the ground sides of the arresters connected to the branch lines and ground them via a switch. An embodiment will now be described with reference to FIG.
The same parts as in FIG. 1 are given the same reference numerals. High voltage winding 1
A branch wire 11 is led out from the middle of the lead wire 3 connecting the high-voltage bushing 2 and the high-voltage bushing 2. Arresters 5 are connected to each branch line 11.
The ground sides of the arresters 5 are commonly connected, and one switch 4 is interposed between this common connection point and the tank inner wall 7. Therefore, arrester 5
In order to operate the arrester 5, it is necessary to close the switch 4, and in order to prevent the arrester 5 from operating, it is necessary to open the switch 4. In such a configuration, in the case of a withstand voltage test, the arrester 5 is disconnected from the ground, that is, the switch 4 is opened, and there is no problem. In the case of an induction test, the two arresters 5 open the switch 4 as well. In this case, the arresters 5 are connected in series, and the voltage applied to each arrester 5 is E/2 times the applied voltage E applied to the high voltage winding 1. In the case of a three-phase device, when three arrester branch circuits are connected in common, the voltage applied to the arrester 5 becomes E/√3. Therefore, in any withstand voltage test, a voltage higher than the operation start voltage is not applied to the arrester 5 with the switch 4 open, making the test possible. Therefore, any test can be performed by opening one switch 4. Note that the above explanation can also be applied to other power distribution equipment such as a switch with a built-in arrester. As explained above, according to the present invention, any test can be performed by opening one switch, the switch is easy to operate, and the test work is very simple.
Whether it is a single-phase or three-phase system, only one switch is required, so the tank size becomes smaller and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of a conventional transformer with a built-in arrester, and FIG. 2 is a block diagram showing an example of a power distribution device with a built-in arrester according to the present invention. In the drawing, 4 is a switch, 5 is an arrester, 7 is a tank inner wall, and 11 is a branch line.

Claims (1)

[Claims] 1 In a device in which the current-carrying part of the main body of power distribution equipment housed in a tank is grounded via an arrester, a branch line is connected to each of the above-mentioned current-carrying parts of each phase, an arrester is connected to each of these branch lines, and this arrester A power distribution device with a built-in arrester, characterized in that the grounding sides of the two are commonly connected, and this common connection point is grounded to the inner wall of the tank via a switch.