JPS63197314A - Direct current transformer - Google Patents

Abstract

PURPOSE:To easily perform the coupling degree operation and the separating operating for the first part and the second part of an annular core by a method wherein a winding, to be used to cancel the magnetic flux on the current of line, is provided. CONSTITUTION:When the second parts 11 and 12 are attached to the first parts 9 and 10 of the first and the second annular cores 2 and 3, a switch 39 is turned ON, and the current of DC line 1 of the direction, in which the magnetic flux generated in the annular cores 2 and 3 will be cancelled, is allowed to flow. As a result, the sucking force of the parts 11 and 12 against the part 9 and 10 is weakened, and the positional relation of both of them before fixing by a screw 30 can be adjusted easily. At this point, when the parts 11 and 12 are brought into the desired relation against the parts 9 and 10, the parts 11 and 12 are fixed by performing a coupling degree operation using a fixing means 26. Subsequently, the switch 39 is turned OFF, and a power source 40 and the circuit of the switch 39 are detached from the terminals 38 and 39 by performing a separating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC current transformer suitable for measuring current in an existing DC line.

[Prior Art] A DC current transformer for measuring a large DC current using the "Ampere-Turn's law" of a saturable reactor is already known. This type of DC current transformer consists of an annular core surrounding the DC line to be measured and a winding wound around this core.

[Problems to be Solved by the Invention] However, there are cases where it is necessary to install a DC transformer without substantially modifying an existing DC line, such as a power supply line in a telephone office. In this case, it is conceivable to divide the annular core of the DC current transformer, arrange the divided cores so as to surround the DC line, and integrate the divided cores so as to form a rear annular core. However, if a large current such as 300OA is flowing in the DC line,
The magnetic flux generated in the core based on this current makes it difficult to attach the split core.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a DC current transformer in which a split core can be easily attached to and removed from an existing DC line.

[Means for Solving the Problems] The present invention for solving the above problems and achieving the above objects includes: an annular core disposed so as to surround a DC line to be measured; the annular core is divided into a first part and a second part, and the first part has an open end into which the DC line to be measured can be inserted. the second portion is formed to close the open end of the first portion, and the first portion and the second portion are formed to surround the DC line to be measured. The first
In the DC current transformer, a winding for canceling the magnetic flux generated in the annular core by the current of the DC line to be measured is attached to the annular core. A DC transformer comprising: an annular core provided in a core, the second part being fixed to the first part and arranged to surround a DC line to be measured; and a current detection winding wound around the annular core. In the flow vessel, the annular core comprises a first part and a second part, the first part is formed with an open end into which the DC line can be inserted, and the second part is formed with an open end into which the DC line can be inserted. a portion is formed to close the open end of the first portion, and a portion that prevents displacement of the joint between the second portion and the first portion is provided on the first or second portion. and a current is applied to the winding for canceling the magnetic flux when fixing the second part to the first part or removing the second part from the first part. The DC current transformer is characterized in that the first part and the second part are arranged so as to surround the inlet, and the second part is arranged so as to surround the inlet. This invention relates to a DC current transformer characterized by being provided with means for fixing the parts.

[Function] When installing this DC current transformer to an existing immovable DC line, the annular core is separated into a first part and a second part, and the DC line is accommodated in the first part. , the open end of the first part is closed with the second part, and then the two are integrated by a fixing means. At this time, if a large current is flowing in the DC line, the magnetic flux based on this will cause the first part and the second part to
and the second part are attracted to each other, and the second part is placed in a predetermined position of the first part.
It becomes difficult to place the parts. Therefore, current is passed through the magnetic flux canceling winding to weaken the attraction.

Thereby, a desired bonding state between the first portion and the second portion can be easily obtained. When the second portion is removed from the first portion, a current is similarly applied to the magnetic flux canceling winding.

[Example] Next, a DC current transformer according to an example of the present invention shown in FIGS. 1 to 5 will be described. FIG. 1 shows the principle of a DC current transformer according to an embodiment of the present invention. Current I,. Existing DC line 1
The two annular cores 2 and 3 surrounding the windings 4 and 5 have Nt turns.
is being rolled around.

The first and second windings 4 and 5 are connected in series so that their polarities are opposite to each other, and an alternating current 6 is connected thereto.
An ammeter 9 is connected via a full-wave rectifier 7 between the power supply 6 and the second winding 5 to detect the current 11 flowing through the winding 4.5. The first and second annular cores 2.3 are each saturable magnetic cores with square hysteresis characteristics.

Therefore, this DC current transformer is constructed using the "Ampere-Turn's law" of a saturable reactor. The DC line 1 serves as a one-turn control winding for the annular core 2.3, and the first and second windings 4, serving as load windings.
5 are N and turns, respectively, so the current I in the DC line 1 is determined by measuring the negative W current, I,. can be known.

By the way, the annular core 2.3 of this embodiment has a first portion 9
, 10 and the second portion 11.12.

Therefore, it becomes possible to install the DC transformer without dismantling or moving the existing DC line 1.

Although FIG. 1 shows a DC current transformer including first and second annular cores 2.3 in principle, in reality the first annular cores 2.3 are mutually connected as shown in FIG. juxtaposed and unified. In addition, the first parts 9, 10 and the second part 11
．． 12 and the covering of the first and second volumes 114.5 are provided.

3, 4 and 5 show the first part 9 of the first annular core 2 and its fixing device in detail.
is a laminated steel plate bent into an arc shape of about 270 degrees, and has a pair of joint end faces 13 degrees and 14 degrees. first part 9
are formed symmetrically with respect to a straight line extending perpendicularly through the center point of this circular arc. The pair of joint end surfaces 13 and 14 are formed to coincide with a plane that is perpendicular to the straight line extending perpendicularly to the front symbol at points other than the center point of the circular arc. The surface area of the pair of connecting end surfaces 13, 14 is therefore larger than the cross-sectional area of the first portion 9, which corresponds to the normal to the circular arc. Therefore, the contact area between the first portion 9 and the second portion 11 becomes large, and the magnetic resistance at the joint becomes small.

The second portion 11 has a pair of joint end surfaces 13 of the first portion 9.
．． It is formed to magnetically connect the 14 darknesses.

This second portion 11 is not formed to match the extension of the arc of the first portion 9, but rather has a pair of connecting end surfaces 13, 1.
4 in the shortest distance.

A pair of bonding surfaces 17 and 18 are provided at one end 15 and the other end 16 of the second portion 11 to bring them into close contact with the pair of bonding end surfaces 13 and 14 of the first portion 9. This coupling surface 17, 18 lies in the same plane as the coupling end surfaces 13, 14 of the first part 9 after assembly according to FIG.

Adjacent to the coupling surface 17.18 of the second part 11 a projecting wall 19.20 is provided. This prominence! N19.20
is located inside the pair of joint end surfaces 13.14 of the first portion 9, and thus prevents the pair of joint end surfaces 13.14 from moving toward each other.

Outer peripheral surfaces 21.22 of both ends 15.16 of the second portion 11
is formed in an arc shape. However, this outer peripheral surface 21.
The radius of the circular arc 22 is larger than the radius of the circular arc of the first portion 9. A flat surface 23 is provided between the pair of outer peripheral surfaces 21 and 22, and a platform 24 is provided at the center of this flat surface 23. It is being The distance between the upper surface 25 of this platform 24 and the center point of the arc of the first portion 9 is shorter than the radius of the arc of the first portion 9.

The fixture 26 for annularly integrating the first part 9 and the second part 11 is made of a steel belt 27 shown in FIGS. 3 and 4, and a metal belt formed in a cylindrical shape. It consists of first and second rods 28, 29 and a screw 30. A belt 27 wound around the outer peripheral surfaces of the first part 9 and the second part 1
is slightly shorter than the length of these outer peripheral surfaces. Therefore, the belt 27 has one end 27a and the other end 27b. One end portion 27a and the other end portion 27b are formed by folding the belt 27 back into a loop shape.

The belt 27 is not fixed to the second part 11 but is fixed to the first part 9. A screw hole 31 is formed in the first rod 28 inserted into one loop-shaped end 27a, and a second rod 2 inserted into the other loop-shaped end 27b is formed with a screw hole 31.
9 is provided with a through hole 32, and the screw 3 has a head 30a.
0 passes through the through hole 32 and is screwed into the screw hole 31.

U-shaped notches 33 and 34 are provided at both ends 27a and 27b of the belt 27, respectively, to facilitate the joining operation.

The winding l14 is wound around the outer periphery of the first portion 9 and the belt 27.

When installing a DC current transformer to the existing DC line 1,
The screw 30 is removed from the first rod 28, the connection between one end 27a and the other end 27b of the belt 27 is released, and the second part 11 is separated from the first part 9 as shown in FIG. .

Since the open width between the pair of joint end surfaces 13 and 14 of the first portion 9 is larger than the width of the DC line 1, it is possible to arrange the first portion 9 at a position surrounding the DC line 1. . Since the DC line 1 is an existing high current line that is fixedly placed, it is impossible to move the DC line 1 and accommodate it in the first section, so it is necessary to move the first section 9. The DC line 1 is housed in this. After that, place the second part 11 on the first part 9 again and
Close the opening in section 9. In order to reduce the magnetic resistance at the joint between the first part 9 and the second part 11,
A pair of connecting end surfaces 13 and 14 of the first part 9 and the second part 1
It is necessary to bring the pair of bonding surfaces 17 and 18 of 1 into close contact with each other. Therefore, the one end 27a and the other end 27b of the belt 27 are connected using the screw 30 and the first and second tp28.29 as shown in FIGS.
By advancing the belt 27, the belt 27 tightens the first and second portions 9°11. Since the first portion 9 is formed in an arc shape, when tightened,
The ends of the first portion 9 tend to deform in a direction in which the distance between them becomes narrower. However, in this embodiment, the protruding wall portions 19, 2
0, the ends of the first portions 9 hit here and are restricted from coming any closer to each other. Therefore, the close contact between the pair of joint end surfaces 13.14 of the first portion 9 and the pair of joint surfaces 17.18 of the second portion 11 is maintained in good condition.

Both ends 27a and 27b of the belt 27 are arranged on the base 24, and the outer peripheral surface 2 of both ends 15° and 16 of the second portion 11
1.22 has an inclination, so when the belt 27 is tightened so that the distance between both ends 27a and 27b becomes short, the outer peripheral surfaces 21 and 22 of both ends of the first portion 11 are pressed downward. A force component is applied from the belt 27, and the pair of bonding surfaces 17 and 18 of the second portion 11 are strongly pressed against the pair of bonding end surfaces 13 and 14 of the first portion 9, resulting in a bonded state with low magnetic resistance. It will be done. Note that the second annular core 3 shown in FIGS. 1 and 2 is configured similarly to the first annular core 2.

By the way, the annular core 2.3 is connected to the first part 9.10 and the second part 9.10.
Which division type of part 11.12 is used, magnetic flux generated in the annular core 2.3 based on the current flowing in the DC line 1 causes an attractive action between the first part 9.10 and the second part 11.12. and the first part 9.10 and the second part 11
．． It becomes difficult to adjust the mutual positional relationship with 12. Therefore, as shown in FIG. 1, magnetic flux canceling windings 1a 35, 36 are wound around the first portions 9.10 of the first and second annular cores 2.3, respectively, and are connected in series with each other. A DC power source 40 is connected to terminals 37.38 of the two windings 1135.36 via a switch 39.

Since the current supply to the winding 35.36 is only required when removing the annular core 2.3, a pair of terminals 37.38
The DC power source 40 is connected only when necessary.

When attaching the second part 11.12 to the first part 9.10 of the first and second annular cores 2.3, the switch 39 is turned on and the current of the DC line 1 is applied to each annular core 2.3. 3. A current is passed in a direction that cancels out the magnetic flux generated inside the tube. This weakens the suction force of the second part 11.12 with respect to the first part 9.10, making it possible to easily adjust the positional relationship between the two parts before they are fixed with the screws 30.

Once the second portion 11.12 is in the desired relationship with respect to the first portion 9.10, the fixture 26 is used to remove the first portion 9.1.
0 to the second part 11.12 and then switch the switch 39 to the OFF state and close the terminal 38.39 as required.
The circuit of power supply 40 and switch 39 is disconnected from the circuit. If it becomes necessary to remove the second part 11.12 from the first part 9.10, the winding 35.36 is also energized to cancel the magnetic flux.

The invention is not limited to the embodiments described above, but can be modified. For example, as shown in FIG. 6, the outer circumferential surface 11a of the second portion 11 may be shaped like an arc. Further, the protruding walls 19 and 20 may be formed into a dovetail groove shape to fit the tip of the first portion as shown in FIG. 6, and in FIGS. Although it is tightened, it may be tightened with multiple screws. Also screw 30
Bolts and nuts may be used instead of the windings 35, 36, and the windings 35, 36 may have one turn relative to the annular core 2, 3. [Effects of the Invention] As is clear from the above, Since the winding is provided for canceling the magnetic flux based on the current of the DC line, the operation of connecting and disconnecting the first part and the second part of the annular core is facilitated.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the principle of a DC current transformer according to an embodiment of the present invention, Fig. 2 is a plan view schematically showing a DC current transformer according to an embodiment, and Fig. 3 is a DC transformer according to an embodiment. A front view showing the annular core of the device and its fixing device, FIG. 4 is a plan view of the annular core and the fixing device shown in FIG. 3, and FIG. FIG. 6 is a front view showing an unseparated state, and FIG. 6 is a sectional view showing a modified annular core. 1... DC line, 2... First annular core, 3...
・Second annular core, 4, 5...Winding, 9...First part, 11...Second part, 13.14...Joining end surface, 19° 20...Protrusion Wall part, 24... Base part, 26
...Fixing tool, 27...Belt, 35.36...Winding for magnetic flux cancellation.

Claims (1)

[Claims] (1) Consisting of an annular core arranged to surround a DC line to be measured, and a current detection winding wound around the annular core, the annular core is divided into a first part and a second part. The first part is formed to have an open end into which the DC line to be measured can be inserted, and the second part closes the open end of the first part. and means for fixing the second part to the first part with the first part and the second part arranged so as to surround the DC line to be measured. In the provided DC current transformer, a winding for canceling magnetic flux generated in the annular core by the current of the DC line to be measured is provided in the annular core, and the second part is provided in the first part. 1. A DC current transformer comprising means for passing a current through a winding for canceling the magnetic flux when fixing the second part or removing the second part from the first part.