JPH028225Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an oil-filled induction electric appliance in which a tank housing the main body of the oil-filled induction electric appliance is grounded via a current transformer.

Although very small, leakage current always flows through the grounding wire of high-voltage equipment. The insulation state of the device can be diagnosed based on the waveform of this leakage current. For these purposes, a tank containing the main body of an oil-filled induction electric appliance such as a transformer is grounded via a current transformer for measuring the leakage current. In this case, conventionally, as shown in Fig. 1, an outdoor insulator type current transformer 2 is installed outside the side wall of an oil-filled induction tank 1, and the tank 1 is grounded through its primary terminal 3. The configuration was such that the leakage current was measured from the side terminal 4. However, this conventional structure has the disadvantage that not only the external dimensions of the oil-filled induction appliance become large but also the cost becomes high. This invention was devised in view of this point, and the purpose is to provide this type of oil-filled induction electric appliance that is small and inexpensive. This object was achieved according to the present invention by the following configuration.

That is, an opening that is oil-tightly closed by a cover is provided in the tank, and a current transformer chamber that includes the opening and is configured to be oil-tight and accommodates the current transformer is provided. The current transformer is housed in the chamber, and the current transformer chamber is communicated with the inside of the tank via a valve to fill the current transformer chamber with oil in the tank. Further, one end of the primary winding of the current transformer is electrically connected to the tank in the current transformer room, and the other end of the primary winding is insulated from the tank and led out to the outside of the current transformer room. The current transformer is grounded, and the secondary winding of the current transformer is insulated from the tank and connected to a terminal leading outside the current transformer room.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a sectional view of an embodiment of the present invention, in which an opening 23 that is oil-tightly closed by a cover 22 is provided in the side wall 21 of the surplus space in the tank 1 that houses the main body of the oil-filled induction electric appliance. An oil-tight current transformer chamber 24 is provided inside the tank 1 by using a part of the side wall 21 including the side wall 21. A current transformer 25 is housed in the current transformer chamber. The opening 2 allows the current transformer to be put in and taken out.
The size of 3 has been determined. The inside of the current transformer chamber 24 and the inside of the tank 1 are communicated through a valve 26 provided in the tank, and the oil 27 inside the tank 1 is filled into the current transformer chamber 24 through the valve 26. The current transformer chamber is also provided with an air vent valve 28 at the top and an oil drain valve (not shown) at the bottom.

One end of the primary winding 29 of the current transformer 25 is connected to the current transformer chamber 2.
The other end of the primary winding 29 is electrically connected to the tank 1 at a terminal 30 inside the current transformer chamber 24, and the other end of the primary winding 29 is grounded via a primary terminal 31 that is insulated from the tank 1 and led out of the current transformer chamber 24. A secondary winding 33 wound around an iron core 32 interlinked with the primary winding 29 is led out of the current transformer room via a secondary terminal 34 for measuring leakage current. Supporting the current transformer 25 and its terminals 31, 34 on the cover 22 has the advantage that assembly and inspection can be made very simple.

FIG. 3 is a diagram showing another different embodiment of the present invention, and the same reference numerals indicate those having the same functions as those described above. This uses a simple bushing-type current transformer 35 as a current transformer, and supports it from the cover 22. One end of the grounding bushing 36, which passes through the current transformer 35 and is led out of the current transformer chamber 24, is connected to the current transformer. In the chamber 24, the terminal 3
0 to the tank 1, and the other end is grounded outside the current transformer room.Although not shown, the secondary winding of the bushing type current transformer is provided on the cover 22 as in FIG. 2 above. Connected to secondary terminal for leakage current measurement. A three-way valve can also be used as the valve 37 disposed between the tank 1 and the current transformer chamber, and in this case, the oil drain valve in the current transformer chamber 24 is not required.

As is clear from the above explanation, in the case where the tank 1 housing the main body of the oil-filled induction electric appliance is grounded via the current transformers 25 and 35, the opening 23 in the tank 1 is oil-tightly closed by the cover 22. is provided, and an oil-tight current transformer chamber 24 including the opening is provided;
The current transformers 25 and 35 are housed in the current transformer chamber, and the tank 1 is filled with insulating oil 27 via valves 26 and 37 provided in the tank 1. Further, one end of the primary winding 29 of the current transformer 25 is connected to the tank 1 via a terminal 30 within the current transformer room 24, and the other end is led out to the outside of the current transformer room via a terminal 31 and grounded. In addition, in order to measure leakage current, the secondary winding of the current transformer is led outside the current transformer room. By configuring as described above, it is possible to obtain a small and inexpensive oil-filled induction electric appliance whose tank is grounded via a current transformer.

[Brief explanation of drawings]

Fig. 1 is a partial side view of a conventional oil-filled induction electric appliance with an outdoor insulator type current transformer attached to a tank, and Figs. 2 and 3 show the current transformer mounting part of different embodiments of the present invention. FIG. 1: Tank, 22: Cover, 23: Opening, 2
4: Current transformer room, 25: Current transformer, 26, 37: Valve,
27: Insulating oil, 30, 31: Terminal, 35: Bushing current transformer.

Claims (1)

[Claims for Utility Model Registration] 1. A tank housing the main body of an oil-filled induction electric appliance is grounded via a current transformer, and the tank is provided with an opening that is oil-tightly closed by a cover, and the opening is closed in an oil-tight manner by a cover. A current transformer chamber is provided, which is oil-tight and includes an oil-tight structure in which the current transformer is housed, and insulating oil is communicated between the current transformer chamber and the inside of the tank through a valve. One end of the primary winding is electrically connected to the tank in the current transformer room, and the other end is grounded via a terminal that is insulated from the tank and led out to the outside of the current transformer room. An oil-filled induction electric appliance characterized in that the next winding is insulated from the tank and connected to a terminal leading outside the current transformer room. 2 Utility Model Registration The oil-filled induction electric appliance according to claim 1, wherein the current transformer is supported by the cover together with the terminals of the current transformer. 3 Utility Model Registration Claims In the oil-filled induction electric appliance according to claim 1 or 2, one end of the current transformer is connected to the tank, and the other end is connected to the tank through a grounding bushing. An oil-filled induction electric appliance characterized by being configured as a bushing current transformer.