JPH03219581A - Monitoring device for zinc oxide type lightning arrester - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a monitoring device for early detection and detection of deterioration of a zinc oxide type lightning arrester.

[Prior art] Figure 3 is, for example, published in the Bulletin of the National Conference of the Institute of Electrical Engineers of Japan (1989), Vol.
379, pages 10-128. FIG. In the figure, a zinc oxide type lightning arrester 1 (hereinafter abbreviated as MOA) connected between the electric line U and the ground is equipped with a current transformer 2 for detecting the current, and the detected current is converted into an electrical signal. A photoelectric converter 3 (Elo in the figure) converts into an optical signal.
) is converted into an optical signal by the optical fiber 3
The signal is input to the lightning arrester monitoring device 6 via A. On the other hand, the voltage of the electric line U is detected by the voltage transformer PT, and is similarly converted into an optical signal by the photoelectric converter 4, and is transmitted to the optical fiber 4A.
The signal is input to the lightning arrester monitoring device 6 via the.

In the lightning arrester monitoring device 6, the above-mentioned optical signals are transmitted through respective photoelectric converters 13 and 14 (
The capacitance leakage current component of the total leakage current is detected by rectifying the output of the current transformer CT, and the resistance bone leakage current is is detected by performing known synchronous rectification on the output of the current transformer CT and the output J of the potential transformer PT.

Generally, when the MOAI deteriorates, the resistive bone leakage current increases, so the deterioration can be detected by measuring the resistive bone leakage current. FIG. 2 is a graph showing the relationship between voltage and current using the degree of deterioration of a zinc oxide type lightning arrester as a parameter. Curve T1 shows the case where there is no deterioration at all, curve T2 or T3 shows the state where there is some deterioration, and curves T4 and T5 show the state where the deterioration has progressed considerably. In the conventional lightning arrester monitoring device 6, the measured resistance bone leakage current value is A/D converted, inputted to the calculator 5, and compared with preset criteria at regular intervals to determine the MO.
The state of the AI is being monitored.

[Problems to be Solved by the Invention] In order to detect deterioration or abnormality of the MOA at an early stage by measuring the resistive bone leakage current, the resistive bone leakage current may be measured at short intervals, for example, every minute. However, in general, the deterioration of the MOA does not progress over a short period of time, but gradually over a long period of time, so measuring at too short a period results in unnecessary measurements, which is not desirable in terms of the efficiency of use of the lightning arrester monitoring device.

[Means for Solving the Problems] A monitoring device for a zinc oxide type lightning arrester according to the present invention uses a current transformer to detect leakage current of a zinc oxide type lightning arrester connected between an electric line and the ground, and also detects the voltage of the electric line with a meter. The resistor leakage current of the zinc oxide lightning arrester is detected by the synchronous rectifier based on the detected leakage current and the voltage of the circuit, and the value of the detected resistor leakage current is set to a predetermined value. It is equipped with a computing unit that compares the value with the value to determine the deterioration of the zinc oxide type lightning arrester, measures the temperature of the element of the zinc oxide type lightning arrester with a temperature measuring means, and according to the measured temperature,
A starting circuit is provided which applies a starting signal with a long cycle at a low temperature and a short cycle when the temperature is high to the arithmetic unit to start the comparison/judgment operation of the arithmetic unit.

[Operation] The temperature of the MOA element is detected, and the measurement cycle of the resistance bone leakage current is changed depending on the temperature.

[Example 1] Fig. 1 shows an example of a monitoring device for a zinc oxide type lightning arrester according to the present invention. In the figure, a zinc oxide type lightning arrester 1 (hereinafter abbreviated as MOA) connected between an electric line U and the ground is provided with a current transformer 2 for detecting its leakage current, and the detected current is transmitted by an electrical signal. Photoelectric converter 3 that converts the signal into an optical signal
(abbreviated as Elo in the figure) is converted into an optical signal and input to the lightning arrester monitoring device 6A via the optical fiber 3A.

On the other hand, the voltage of the electric line U is detected by the potential transformer PT, and similarly converted into an optical signal by the photoelectric converter 4,
The signal is input to a lightning arrester monitoring device 6A via an optical fiber 4A. Both optical signals are transmitted to each photoelectric converter 1 provided in the lightning arrester monitoring device 6A that converts the optical signal into an electrical signal.
3 and 14 (abbreviated as O/E in the figure) into an electrical signal.

The output of the photoelectric converter 13 is applied to a synchronous rectifier 16 and a full-wave rectifier 17 via a switch 15 for selecting the outputs of a large number of current transformers. The output of the photoelectric converter 14 is also applied to a synchronous rectifier 16, and resistive bone leakage current is measured by a known synchronous rectifier.

On the other hand, the leakage current corresponding to the capacitance is detected by the aftermath rectifier 17 . The outputs of the synchronous rectifier 16 and full wave rectifier 17 are A/D
The signal is A/D converted by the converter 18 and input to the arithmetic unit 5A.

The MOAI is equipped with a temperature detector 7 for detecting the temperature of its elements, and its detection output is input to the starting device 8. Since the temperature of the MOAI element increases due to the resistive bone leakage current flowing through the element, the state of deterioration of the element can generally be estimated by measuring the temperature rise.

The starting device 8 outputs a starting signal with a cycle corresponding to the temperature detected by the temperature detector 7, and the starting signal is sent to the lightning arrester monitoring device 6A.
The signal is input to the arithmetic unit 5A via the switch 2o. When the calculator 5A receives the activation signal from the activation device 8, it compares the resistance leakage current obtained based on the detected values of the current transformer 2 and the potential transformer PT with a preset reference value, and determines the MOA. Determine the condition. The above activation signal is
When the detected temperature of the MOA is below a predetermined value, it is output at a cycle of, for example, one day, but when the detected temperature exceeds a predetermined value, it is output at a frequency corresponding to the temperature. Further, when the amount of heat generated exceeds the amount of heat dissipated and the rate of increase in temperature becomes greater than a predetermined value, a start signal is output at a cycle of, for example, one minute.

In response to this activation signal, the calculator 5A compares the resistance leakage current with a predetermined value set in advance, and when it exceeds the predetermined value, it displays on the display device 21 that the MOAI has deteriorated, and also displays the deterioration of the MOAI as necessary. Accordingly, the signal can also be output from the terminal 22 to an external device.

[Effects of the Invention] According to the present invention, the measurement cycle of resistance leakage current, which indicates deterioration of the element of a zinc oxide lightning arrester, is changed depending on the temperature of the element, and when the temperature is low, the measurement cycle is lengthened. However, as the temperature rises, it becomes shorter. Therefore, when the temperature is low and it is estimated that the element has not deteriorated yet, by measuring at a long cycle, it is possible to prevent unnecessary high frequency of measurement.
Furthermore, when it is estimated that the temperature has increased and deterioration has progressed, the measurement cycle is shortened and measurements are taken frequently, allowing early detection of failures.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a monitoring device for a zinc oxide type lightning arrester according to the present invention, Fig. 2 is a graph showing the relationship between voltage and current with the degree of progress of deterioration as a parameter, and Fig. 3 is a zinc oxide lightning arrester according to the prior art. FIG. 2 is a block diagram of a monitoring device for a lightning arrester.

Claims (1)

[Claims] (1) A current transformer for detecting the leakage current of a zinc oxide lightning arrester connected between the electric line and the ground, and an instrument transformer for detecting the voltage of the electric line, based on the detected leakage current and voltage of the electric line. A synchronous rectifier that detects the resistance leakage current of a zinc oxide type lightning arrester, a computing unit that compares the value of the detected resistance leakage current with a predetermined value and determines the deterioration of the zinc oxide type lightning arrester, and a zinc oxide type lightning arrester. A temperature measuring means for measuring the temperature of the element of the lightning arrester, and a starting signal having a long cycle at low temperatures and a short cycle at high temperatures, depending on the measured temperature, is applied to the arithmetic unit, and the start signal of the arithmetic unit is A monitoring device for a zinc oxide type lightning arrester, comprising a starting circuit that starts a comparison judgment operation.