JPS6029074B2 - Lightning arrester deterioration detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a snow catcher deterioration detection method for detecting deterioration of a capless closed type earth arrester having a resistor with excellent non-linear resistance characteristics.

A lightning arrester has a resistor with excellent non-linear resistance characteristics, and its high-voltage lead wire is connected to the high-voltage terminal of the equipment to be protected.

For this reason, the nonlinear resistor deteriorates due to continuous application of electricity over a long period of time and the attack of surges such as lightning. This deterioration is a phenomenon in which the nonlinearity of the nonlinear resistor deteriorates, and the small leakage current that flows in response to the constantly applied voltage gradually increases. When the current exceeds a certain level, heat generated internally causes a state of thermal runaway in which the leakage current further increases, destroying the nonlinear resistor. Therefore, in order to maintain the reliability of the lightning arrester, it is necessary to monitor the degree of deterioration of the nonlinear resistor. FIG. 1 is a connection diagram in which a conventional lightning arrester deterioration detection method is connected to a nutrient device.

In the figure, 1 is a grounded tank, 2 is this grounded tank 1
A space filled with a gas having high dielectric strength such as SF6 gas, 3a to 3c are three-phase non-linear resistors made of zinc oxide, 4a to 4c are three-phase high voltage side lead wires, and 5 is a three-phase high voltage side lead wire. Insulating material supports supporting the three-phase high-voltage side lead wires 4a-4c, 6a-6c are three-phase sealed insulated terminals 7a-7
c is a three-phase low-voltage side lead wire, 8a to 8c are three-phase ammeters, 9a to 9c are ammeter protection resistors connected to the low-voltage side lead wires 7a to 7c, respectively, and 10a to 10c are three-phase currents. The meter protection gaps 11a to 11c are short circuit switches. In addition, the grounding tank 1, the non-linear resistors 3a to 3
c, high voltage side lead wires 4a to 4c, insulating material smoother 5, sealed insulated terminals 6a to 6c, and low voltage side lead wires 7a to
7c constitutes a capless sealed lightning arrester. Next, the operation of the lightning arrester deterioration detection method according to the above configuration will be explained.

The nonlinear resistors 3a to 3c of each phase are connected to high voltage terminals of equipment to be protected via high voltage side lead wires 4a to 4c, respectively.

Since the resistance values of the non-linear resistors 3a to 3c are very high, the non-linear resistors 3a to 3c can withstand surges caused by lightning, etc.
The resistance value of c is extremely low, making it possible to prevent a rise in the voltage of the device, and suppressing the leakage current to a level that is small enough to allow long-term operation with respect to the constantly applied voltage. Currents on the resistance voltage side of the nonlinear resistors 3a to 3c are detected by ammeters 8a to 8c of each phase, respectively. Note that the ammeter protection resistors 9a to 9c and the ammeter protection gaps 10a to
10c opens the short circuit switches 11a to 11c and measures the current, and if a surge such as lightning strikes,
This is to protect each of the ammeters 8a to 8c from overcurrent.

However, in conventional earth arrester deterioration detection methods, nonlinear resistors have high nonlinear resistance characteristics and relatively large dielectric constants, so when used in connection with a commercial frequency circuit, they are used as static resistors rather than resistors. Acts as a dielectric with high capacitance.

For this reason, when measuring the current, there is a drawback that the degree of deterioration of the resistance component, which is directly related to deterioration, cannot be detected with high sensitivity. In view of the above points, the present invention was made to solve such problems and eliminate such drawbacks.The purpose of the present invention is to use a simple configuration to detect only the leakage current of the resistance directly related to deterioration. To provide a lightning arrester deterioration detection method that can detect the degree of deterioration with high sensitivity, can also detect the deterioration of snow arresters with high accuracy, and can maintain high reliability of power transmission and distribution circuits. be.

In order to achieve such an object, the present invention provides a common ammeter that is connected to the three-phase low-voltage side lead wire via a resistor and detects the low-voltage side current of each nonlinear resistor, and A parallel circuit including an ammeter protection gap and an ammeter protection switch connected between the low-voltage side lead wire of the phase and the ground is provided.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a connection diagram in which an embodiment of the earth arrester deterioration detection method according to the present invention is connected to an earth arrester. In FIG. 2, the same symbols as in FIG. 1 indicate corresponding parts, and 12 is a resistor whose one end is connected to the three-phase low voltage side lead wires 7a to 7c;
13 is an ammeter whose one end is connected to the other end of the above-mentioned resistor 1 and 12, and whose end is connected to ground; 14 and 15 are an ammeter protection gap and an ammeter protection switch connected in parallel, respectively; It is connected to one end of the resistor 12, and its terminal is connected to ground. Next, the operation of the lightning arrester deterioration detection method according to the above configuration will be explained.

The nonlinear resistors 3a to 3c of each phase are connected to high voltage terminals of the equipment to be protected via high voltage side lead wires 4a to 4c, respectively.

Since the nonlinearity of the resistance values of the nonlinear resistors 3a to 3c is large, the nonlinear resistors 3a to 3c are
The resistance values of a to 3c become significantly low, and it is possible to prevent voltage increases in the equipment. Moreover, for a voltage that is constantly applied, leakage current can be suppressed to a level that is small enough to allow long-term operation. Next, a case where the nonlinear resistors 3a to 3c deteriorate will be described.

The nonlinearity of the resistance values of the nonlinear resistors 3a to 3c is large, and their capacitances are relatively large.

Therefore, with respect to the constantly applied commercial frequency voltage, the current flowing through the resistance due to deterioration and the current flowing through the capacitance have different phases. Further, for the three-phase AC voltage, each phase differs by 2/3 rad in electrical angle, as shown by the broken lines in FIGS. 3A to 3C. For this reason, each nonlinear resistor 3a
When the deterioration of ~3c has progressed, the nonlinear resistors 3a~3
The three-phase current flowing through c consists of the sum of a sine wave current due to a capacitance that is phase-lead of the applied voltage by T/2 and a current of a resistance component having a pulse-like peak that is in phase with the applied voltage. This current waveform can be shown as a solid line in FIGS. 3A to 3C. Therefore, the current corresponding to this resistance does not form a sine wave due to the nonlinearity of the nonlinear resistors 3a to 3c.
Therefore, when the ammeter protection switch 15 is open, the current flowing through the ammeter 13 is a combination of the currents shown by solid lines in FIGS. 3A to 3C, but the capacitance of each phase is balanced. In this case, as shown in Figure 3D, the sinusoidal current components due to capacitance completely cancel each other out and become zero, and the current due to resistance due to deterioration becomes a steep pulse-like current. Therefore, the three-phase components do not cancel each other out and remain as they are. Therefore, only the current corresponding to the resistance due to deterioration can be accurately detected by the ammeter 13, and the degree of deterioration can be ascertained. Furthermore, since the change in capacitance due to deterioration is small, deterioration can be similarly accurately determined even when only one or two of the three phases have deteriorated.
FIG. 4 is a connection diagram in which another embodiment of the lightning arrester deterioration detection method according to the present invention is connected to a lightning arrester.

In FIG. 4, parts that are the same as those in FIG. 2 are given the same reference numerals and explanations will be omitted. 16' is a cloud phase current transformer.

One end of the primary winding is connected to the low voltage side lead wire 7 of the nonlinear resistors 3a to 3c via resistors 17a to 17c, respectively.
a to 7c, and the other end is connected to ground. Further, an ammeter 13 is connected to the secondary winding. It should be noted that the operation of the arrester deterioration detection method according to the above configuration is of course the same as that shown in FIG. Effective when grounding is not possible.

Moreover, since the ammeter is not directly connected to the primary side, safety is increased. Moreover, by adjusting the number of turns of each of the three phases of the primary winding of the zero-phase current transformer 16 in accordance with the variation in the capacitance values of the nonlinear resistors 3a to 3c, the nonlinear resistor 3a
The influence of variations in capacitance values of ~3c can be completely removed. As explained above in detail, the lightning arrester deterioration detection method according to the present invention has an extremely simple structure,
Furthermore, deterioration of the earth arrester can be detected with high accuracy.

Therefore, there are effects such as being able to maintain high reliability of the power transmission and distribution circuit.

[Brief Description of the Drawings] Fig. 1 is a connection diagram in which a conventional earth arrester deterioration detection method is connected to a lightning arrester, and Fig. 2 is a connection diagram in which an embodiment of the earth arrester deterioration detection method according to the present invention is connected to a lightning arrester. , FIG. 3D are diagrams showing waveforms of various parts in FIG. 2, and FIG. 4 is a connection diagram in which another embodiment of the lightning arrester deterioration detection system according to the present invention is connected to a lightning arrester. 1...Grounded tank, 2...Space, 3a-3
c...Non-linear resistor, 4a-4c...High-voltage side lead wire, 5...Insulator spacer, 6a-6
c... Sealed insulated terminal, 7a to 7c... Low voltage side lead terminal, 8a to 8c... Ammeter, 9a
~9c... Resistor for ammeter protection, 10a~10c
...Ammeter protection gap, 11a to 11c...
...Short switch, 12...Resistor, 13...
... Ammeter, 14... Ammeter protection gap,
15... Ammeter protection switch, 16...
...Zero phase current transformer. Note that the same reference numerals indicate the same or equivalent parts. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. Connect the high voltage side of a sealed lightning arrester equipped with a 3-phase non-linear resistor to a 3-phase AC circuit via a 3-phase high voltage side lead wire, and connect the low voltage side of the sealed lightning arrester to a 3-phase AC circuit via a 3-phase low voltage side lead wire. In a lightning arrester deterioration detection device that is connected to a three-phase sealed insulated terminal and measures the current flowing through the non-linear resistor on the low voltage side to detect deterioration of the arrester, a common ammeter that is connected to the ground and adds and detects the low voltage side current of each nonlinear resistor; an ammeter protection gap and an ammeter protection switch that are connected between the three-phase low voltage side lead wire and ground; A lightning arrester deterioration detection method characterized by comprising a parallel circuit.