JPH074586Y2 - Current transformer for fault current detection - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a current transformer for detecting a fault current, and more specifically, a current transformer for detecting a fault current such as a ground fault current generated in an electric device such as a switch. It is related to vessels.

[Conventional technology]

Conventionally, as this type of current transformer, the one for ground fault current detection shown in FIG. 4 can be mentioned. The current transformer 31 is externally inserted into a through hole 2a provided in the switch case 2 through a packing 32, and a fixing member 33 is screwed and fixed in the case 2. The body block 34 of the current transformer 31 is manufactured by resin molding, and the conductor bar 35 and the coil C made of stainless steel are inserted inside during molding. Both ends of the conductor rod 35 protrude inside and outside the switch case 2,
It is connected to the inner wall of the case via a lead wire 36 inside the case 2 and is grounded via a lead wire 37 outside the case 2.

Then, when a ground fault occurs, the ground fault current flows to the switch case 2
Through the lead wire 36, the conductor rod 35, and the lead wire 37 to the ground side, and the ground fault current flowing in the conductor rod 35 is detected by the coil C. As a result, for example, the switch is opened by the relay. It is designed to disconnect the distribution line.

[Problems to be solved by the device]

However, the current transformer 31 is required to have various specifications according to the type of switch and the like, and the number of products to be manufactured is not so large. Therefore, the main body block 34 of the current transformer 31
It is very uneconomical to manufacture a resin molding die for molding, and there is a problem that the manufacturing cost of the current transformer 31 is increased.

An object of the present invention is to provide a current transformer for detecting a fault current, which does not require a resin molding die at the time of manufacturing and can be adapted to high-mix low-volume production to reduce the manufacturing cost.

[Means for Solving the Problems]

The present invention cuts a synthetic resin material to form a main body block having an accommodating portion, and disposes the main body block on one side of an electric device case to provide a mounting bracket for covering the opening of the accommodating portion. Current that flows through the conductor rod inside the accommodating portion while electrically connecting the inner end of the conductor rod whose outer end is grounded and is provided through the accommodating portion to the mounting bracket. The gist of the present invention is a current transformer for detecting a fault current in which a current detection element for detecting a current is detachably arranged.

[Action]

The fault current flows from the electric equipment case to the ground side via the mounting bracket and the conductor rod, and the fault current flowing in the conductor rod is detected by the current detection element, and countermeasures are taken based on the detection result. Since the main body block of the current transformer having such an action is manufactured by cutting, when changing the shape of the main body block due to the change of the specifications of the current transformer, it is manufactured by resin molding. It is possible to easily change without preparing a new resin molding die as in the case. Further, since the conductor rod is electrically connected to the electric device case by using the mounting bracket, the lead wire for connecting the electric device case and the conductor rod is omitted.

〔Example〕

An embodiment in which the present invention is embodied in a current transformer for detecting a ground fault current used in a switch will be described below with reference to FIGS.

The current transformer 1 of this embodiment is attached to one side of a switch case 2 as an electric device case. The main body block 3 of the current transformer 1 is held in a mounting bracket 4 that is bent in a concave shape, and both ends of the mounting bracket 4 are fixed to stud bolts 6 on the inner wall of the switch case 2 by four nuts 5. ing. The main body block 3 has a cylindrical shape made of synthetic resin, and a through hole 7 as a housing is formed at the center thereof. The outer shape and the through hole 7 of the main body block 2 are all made of a synthetic resin material. Is being cut.

The through hole 7 is composed of a coil accommodating portion 8 opening upward, a packing accommodating portion 9 opening downward, and an insulating material accommodating portion 10 between the accommodating portions 8 and 9, and each accommodating portion 8 to 10 has a cross section. It has a circular shape. A conductor rod 11 is inserted and arranged from above in the through hole 7, and a flange portion 11a formed at the center of the conductor rod 11 contacts the lower wall of the coil housing portion 8 to position the conductor rod 11. The upper end of the conductor rod 11 is formed in a rectangular shape in cross section and is fitted into the through hole 4a formed in the mounting metal fitting 4. Since the upper end is in contact with the mounting metal fitting 4 as described above, the conductor rod 11 is mounted on the mounting metal fitting. It is electrically connected to the switch case 2 via 4. Further, the lower end of the conductor rod 11 projects to the outside of the case 2 through the through hole 2a of the switch case 2, and one end of a lead wire 14 for grounding is inserted by a bolt 13 into an insertion hole 12 penetrating to the lower end thereof. It is fixed by tightening.

Therefore, when a ground fault occurs, a ground fault current flows from the switch case 2 to the ground side through the mounting bracket 4, the conductor rod 11 and the lead wire 14.

An insulating material 15 made of a cylindrical rubber material or the like is arranged in the insulating material housing portion 10 so as to surround the conductor rod 11.
The lower part of the switch protrudes outside the case through the through hole 2a of the switch case 2. The insulating material 15 is a collar portion 15a formed on the upper portion.
Is prevented from falling down. Further, a packing 16 is arranged in the packing accommodating hole 9 and the packing 16
Maintains airtightness between the switch case 2 and the main body block 3 around the insulating material 15.

A coil 17 as a current detecting element is arranged in the coil housing portion 8 so as to surround the conductor rod 11, and a detection current is generated in the coil 1 by a ground fault current flowing in the conductor rod 11. Packing 18 is placed above and below the coil 17, respectively.
The packings 18 keep airtight between the fitting 4 and the coil 17, and between the coil 17 and the collar portion 11a of the conductor rod 11 and electrically insulate. The coil 17 is connected to a relay (not shown) via a lead wire 19.

Then, when a ground fault current flows through the conductor rod 11 due to a ground fault, a detection current is generated in the coil 17, and a signal from the coil 17 causes a switch to be opened by, for example, a relay to disconnect the distribution line.

As described above, in the ground fault current detecting current transformer 1 of this embodiment, the main body block 3 that holds the conductor rod 11, the coil 17, and the like.
Is manufactured by cutting with a lathe. Therefore, when the outer shape of the main body block 3 and the shape of the through hole 7 are changed in accordance with the change of the specifications of the current transformer 1, when the resin molding is used, Thus, it is possible to easily change without preparing a new resin molding die. Therefore, the manufacturing cost of the current transformer 1 can be suppressed at a low cost even when the current transformer 1 is manufactured in a variety of small quantities.

Also, using the mounting bracket 4 for the switch case 2, a conductor rod
Since 11 is made conductive, the lead wire for connecting the switch case 2 and the conductor rod 11 can be omitted.
Therefore, it is not necessary to connect the lead wire when installing the current transformer 1, and the current transformer 1 can be installed more easily.

The present invention is not limited to the above-described embodiment. For example, in the above-mentioned embodiment, the current transformer 1 is attached from the inside of the switch case 2, but as shown in FIG. The current transformer 21 may be attached from the outside. Explaining this another example, the main body block 22 of the current transformer 21 manufactured by cutting is held between the mounting bracket 23 and the mounting plate 24. In this state, the mounting bracket 23 holds the switch case 2 Is inserted from the outside into the through hole 2a. Both sides of the mounting bracket 23 are mounting plates
The stud bolt 25 of the switch case 2 is piled up with 24
On the other hand, the nut 26 is tightened together with the packing 26 for keeping airtightness sandwiched therebetween. Even in such a configuration, since the main body block 22 is manufactured by cutting, the manufacturing cost of the current transformer 1 can be suppressed at low cost, and the switch case 2 and the conductor rod 11 are attached to the mounting bracket.
The lead wire can be omitted because it is electrically connected using the 23 and the stud bolt 25.

Further, although the current transformer 1 is installed on one side of the switch case 2 in the above embodiment, for example, if the cover of the switch case 2 is electrically connected to the switch case 2. The current transformer 1 may be installed on the lid. The electric equipment case of the present invention also includes members attached to the case such as the lid.

Further, although the coil 17 is used as the current detection element for detecting the current flowing through the conductor rod 11 in the above-mentioned embodiment, a hall element may be used instead.

On the other hand, although the main body block 3 is cut into a cylindrical shape by a lathe in the above embodiment, it may be cut into a square shape with a milling cutter, for example.

[Effect of device]

As described above in detail, according to the current transformer for detecting a fault current of the present invention, it is possible to reduce the manufacturing cost by adapting to high-mix low-volume production without the need for a resin molding die during production. Demonstrate.

[Brief description of drawings]

1 and 2 show the current transformer of the embodiment, FIG. 1 is a cross-sectional view showing the installed state of the current transformer, FIG. 2 is a plan view of the same current transformer,
FIG. 3 is a sectional view showing an installed state of a current transformer of another example, and FIG. 4 is a sectional view showing an installed state of a conventional current transformer. 2 is a switch case as an electric equipment case, 3 and 22 are main body blocks, 4 and 23 are mounting brackets, 7 is a through hole as a housing, 11 is a conductor rod, and 17 is a coil.

Claims (1)

[Scope of utility model registration request] 1. A main body block (3,22) having a housing (7) is formed by cutting a synthetic resin material, and the main body block (3,22) is used as a part of an electric equipment case (2). Mounting brackets (4,23) arranged on the side to cover the opening of the accommodating part (7)
And the inner end of the conductor rod (11) whose outer end is grounded, is electrically connected to the mounting bracket (4, 23) through the accommodation part (7). A fault current detecting current transformer, wherein a current detecting element (17) for detecting a current flowing through the conductor rod (11) is detachably arranged inside the accommodating portion (7).