JP2886779B2 - Ground rod for surge arrester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grounding rod for an arrester, and more particularly to a grounding rod for an arrester for discharging a lightning impulse generated in the arrester to the ground.

[0002]

2. Description of the Related Art FIG. 4 is a view showing the structure of a conventional lightning arrester grounding rod 31 and its use state.
FIG. 6 is a diagram showing a lightning damage blackout accident prevention circuit provided in 6.

[0003] Referring to FIG. 4, a lightning arrestor power failure accident prevention circuit includes a lightning arrester ground rod 31, a ground wire 32 and a lightning arrester 33.
including. The lightning arrester ground rod 31 is a copper rod processed into a pile shape, and is driven deep into the ground so as to be in close contact with the ground.

The lightning arrester 33 is fixed to a high-voltage arm 35 horizontally provided at the upper end of a utility pole 34. The lightning arrester 33 includes a ground side terminal 33a and a high voltage side terminal 33b, and the ground side terminal 33a is a ground wire 32 (2.6 mm diameter copper wire).
And the high voltage side terminal 33b is connected to the high voltage distribution line 36.

The lightning arrester 33 has a predetermined discharge starting voltage Vth
(38 kV to 55 kV) and a predetermined discharge stop voltage Vt
1 (20 kV to 33 kV). Terminals 33a, 33b
When the voltage between the terminals 33a and 33b rises to become equal to or higher than the discharge start voltage Vth, the terminals 33a and 33b are brought into conduction, and
When the voltage between the terminals 33a and 33b falls to or below the discharge stop voltage Vtl, the terminals 33a and 33b are insulated. When the voltage between the terminals 33a and 33b is a normal high voltage distribution voltage (6.0 kV), the terminals 33a and 33b are in an insulated state.

When a lightning strike occurs in the high-voltage distribution line 36 and the voltage of the high-voltage distribution line 36 exceeds the discharge starting voltage Vth, a conduction state is established between the terminals 33a and 33b of the lightning arrester 33, and the lightning impulse current It becomes a ground line. It is discharged to the ground via the grounding rod 32 and the grounding rod 31. Lightning impulse current It
Discharge, the voltage of the high voltage distribution line 36 becomes the discharge stop voltage V
When it becomes tl or less, the terminals 33a and 33b of the lightning arrester 33 become insulated.

Therefore, it is possible to prevent the voltage of the high-voltage distribution line 36 from becoming higher than the discharge starting voltage Vth,
It is possible to prevent the insulator for the high-voltage distribution line 36 and various devices from being destroyed by the lightning impulse voltage, thereby preventing a power failure accident.

[0008]

By providing such a lightning damage accident prevention circuit, a power failure due to a lightning strike can be completely prevented. However, in reality, there are still many power failures due to a lightning strike.

The cause is considered as follows. That is, as shown in FIG. 5, when the resistance of the ground line 32 is R, the inductance of the ground line 32 is L, the contact resistance between the ground rod 31 and the ground is Re ', and the frequency of the lightning impulse is f, Impedance Z 'between line 36 and ground
Is represented by the formula Z ′ = R + Re ′ + j2πfL.

In this equation, the frequency f of the lightning impulse
Is larger than expected, the impedance Z 'between the high-voltage distribution line 36 and the ground has a considerably large value, and the lightning impulse generated in the high-voltage distribution line 36 cannot be rapidly discharged to the ground. It is probable that an accident has occurred.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a grounding rod for a lightning arrester capable of rapidly discharging a lightning impulse generated in the lightning arrester to the ground.

[0012]

A grounding rod for an arrester according to the present invention is a grounding rod for an arrester for discharging a lightning impulse generated in the arrester to the ground, and is formed in a pile shape.
A copper pipe driven into the ground, a metal rod provided in the copper pipe, connected to the lightning arrester via a ground wire, and a resin filled between the copper pipe and the metal rod. And a capacitance between the copper tube and the metal rod for compensating for the inductance of the ground wire so that the impedance between the lightning arrestor and the ground becomes only a pure resistance component.

Further, at least a part of the opposing surface of the copper tube and the metal bar may be provided with irregularities.

[0014]

The grounding rod for an arrester according to the present invention comprises a copper pipe having a pile shape, a metal rod provided in the copper pipe, and a resin filled between the copper pipe and the metal rod. Between the metal rods, there is provided a capacitance C for compensating for the impedance j2πfL due to the inductance L of the ground wire by the impedance −j / 2πfC so that the impedance between the lightning arrester and the ground becomes only a pure resistance component. Therefore, the impedance between the lightning arrester and the ground can be significantly reduced, and the lightning impulse generated in the lightning arrester can be quickly discharged to the ground.

Also, if the copper tube and the metal bar are provided with irregularities on the opposing surface, the opposing area between the copper tube and the metal bar can be increased to increase the capacitance C between the copper tube and the metal bar. The rod can be reduced in size. In addition, it is possible to improve the adhesiveness between the copper tube or the metal rod and the resin, thereby improving the mechanical reliability of the ground rod.

[0016]

FIG. 1 is a partially omitted sectional view showing the structure of a grounding rod 1 for an arrester according to an embodiment of the present invention. Referring to FIG. 1, a grounding rod 1 for an arrester is filled with a grounded copper tube 2, a copper bar 3 arranged at the center of the grounded copper tube 2, and a space between the grounded copper tube 2 and the copper bar 3. The capacitance C between the copper tube 2 and the copper bar 3 is set to a predetermined value including the polyester resin 4 and the connecting lead wire 5.

The grounding copper tube 2 has a tip processed into a conical shape.
The rear end is closed flat and formed into a pile shape, so that it can be easily driven into the ground.

On the surface of the copper rod 3, a number of irregularities 3a are formed. The unevenness 3a improves the adhesion between the copper bar 3 and the resin 4 and increases the opposing area between the copper bar 3 and the grounded copper tube 2 to increase the capacitance C between the copper bar 3 and the grounded copper tube 2. Is formed for.

The connection lead wire 5 is connected to one end of the copper rod 3 through a lead wire hole 4a opened at the rear end of the copper tube 4.

FIG. 2 is a partially broken perspective view illustrating the use state of the grounding rod 1 for such an arrester. Lightning arrester 33
Or replace the ground wire 32 or ground rod 31
At the time of inspection, the ground rod 1 shown in FIG.
, And the connecting lead wire 5 of the ground rod 1 is connected to the ground rod 31 or the ground wire 32.

FIG. 3 is a circuit diagram showing an equivalent circuit between the high voltage distribution line 36 and the ground in FIG. Assuming that the contact resistance between the copper tube 2 of the ground rod 1 and the ground is Re, the connection lead wire 5
The impedance Z between the ground and the ground is given by the following equation: Z = Re−j / 2
It is represented by πfC.

Assuming now that, for simplicity, all the lightning impulse current It flows toward the ground rod 1, the impedance Z between the high-voltage distribution line 36 and the ground is given by the equation Z = R +
Re + j (2πfL−1 / 2πfC). Therefore, if the capacitance C is set so that 2πfL = １ ／ πfC, the impedance Z can be significantly reduced. Therefore, the lightning impulse generated in the high-voltage distribution line 36 can be quickly discharged to the ground, and a power failure due to a lightning strike can be prevented.

In this embodiment, the copper bar 3 is arranged at the center of the copper tube 2, but the invention is not limited to the copper bar 3.
It may be an iron bar or any metal bar.

Although the irregularities 3a are provided only on the surface of the copper rod 3, it is more preferable to provide it on the inner peripheral surface of the copper tube 2.

Although the polyester resin 4 is filled between the copper tube 2 and the copper bar 3, any resin having a high dielectric constant may be used. It is preferable that the dielectric constant is about 3.0 to 4.5.

[0026]

As described above, according to the present invention, the impedance -j / 2π due to the capacitance C of the ground rod is obtained.
Since the impedance j2πfL due to the inductance L of the ground line can be compensated by fC, the impedance between the arrester and the ground can be greatly reduced. Therefore, the lightning impulse generated in the lightning arrester can be quickly discharged to the ground, and a power failure due to a lightning strike can be prevented.

Also, if the copper tube and the metal bar are provided with irregularities on the opposing surface, the opposing area between the copper tube and the metal bar can be increased, and the capacitance C between the copper tube and the metal bar can be increased. The rod can be reduced in size. In addition, it is possible to improve the adhesiveness between the copper tube or the metal rod and the resin, thereby improving the mechanical reliability of the ground rod.

[Brief description of the drawings]

FIG. 1 is a partially omitted sectional view showing a configuration of a grounding rod for an arrester according to an embodiment of the present invention.

FIG. 2 is a partially broken perspective view showing a use state of the grounding rod for an arrester shown in FIG. 1;

FIG. 3 is a circuit diagram showing an equivalent circuit between the high-voltage distribution line and the ground in FIG. 2;

FIG. 4 is a partially broken perspective view showing a configuration of a conventional grounding rod for an arrester and its use state.

FIG. 5 is a circuit diagram showing an equivalent circuit between the high-voltage distribution line and the ground in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 31 Grounding rod for lightning arrester 2 Copper tube 3 Copper rod 3a Irregularity 4 Polyester resin 5 Connecting lead 32 Grounding wire 33 Lightning arrester 34 Electric pole 35 High voltage arm 36 High voltage distribution line

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-12681 (JP, A) JP-A-60-62070 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01R 4/66 H01R 43/00 H02G 7/00 H02G 13/00

Claims (2)

(57) [Claims] 1. A lightning arrester grounding rod for discharging a lightning impulse generated in a lightning arrester to the ground, comprising: a copper tube formed in a pile shape and driven into the ground; and provided in the copper tube; A metal rod connected to the lightning arrester via a ground wire; and a resin filled between the copper tube and the metal rod, wherein the inductance of the ground wire is compensated between the copper tube and the metal rod. A grounding rod for a lightning arrester, characterized by having a capacitance for making the impedance between the lightning arrester and the ground only a pure resistance component. 2. The grounding rod for an arrester according to claim 1, wherein irregularities are provided on at least a part of an opposing surface of the copper tube and the metal rod.