JPH089650Y2 - Insulation monitoring device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an insulation monitoring device for electric equipment used in substation equipment and the like.

[Conventional technology]

It is important to monitor the insulation of electrical equipment such as substation equipment and prevent accidents such as ground faults. Usually, insulation deterioration is judged by the presence or absence of detection of an electrical pulse signal called partial discharge.

A conventional insulation monitoring device will be described with reference to FIG.

FIG. 3 is a block diagram of a conventional insulation monitoring apparatus, for example, when the gas insulation switchgear (GIS) 1 is used as an electric device.

This insulation monitoring device is configured to detect a broadband electromagnetic wave that is secondarily generated when a partial discharge is generated, by the antenna 2.

Then, the electromagnetic wave detected by the antenna 2 is narrow-band detected by the tuning amplifier 3 in a frequency band excluding a part of the band such as a broadcast wave and output to the determination unit 4.

The determination unit 4 performs determination processing of the output signal from the tuning amplifier 3. In the determination process, for example, when the output signal is continuously detected and the duration time exceeds a certain set value, an alarm output is issued.

[Problems to be solved by the device]

However, in the above conventional configuration, there are noises having a signal pattern similar to partial discharge, such as motor brush noises, electric drills, electrostatic precipitators, oil stoves, and other ignition devices. May be emitted.

An object of the present invention is to provide an insulation monitoring device that prevents malfunction due to noise and has high accuracy in determining insulation deterioration.

[Means for solving the problem]

The insulation monitoring apparatus of the present invention comprises an antenna, a tuning amplifier, a judgment unit and a timer.

The antenna is designed to detect a broadband electromagnetic wave that is secondarily generated when a partial discharge occurs.

Then, the tuning amplifier is adapted to perform narrow band detection of the electromagnetic wave detected by the antenna except for a part of the band.

The judgment unit judges the output of the tuning amplifier and issues an alarm signal if there is an abnormality.

The timer outputs an alarm at a fixed time of midnight based on an alarm signal generated by the determination unit.

[Action]

According to the configuration of the present invention, the broadband electromagnetic wave secondarily generated when the partial discharge occurs is detected by the antenna, and the tuning amplifier performs narrow band detection except for a part of the band of the electromagnetic wave detected by the antenna. Then, the judgment unit judges the output of the tuning amplifier, and if it is abnormal, an alarm signal is generated, and the timer outputs a warning output in a fixed time zone at midnight based on the alarm signal generated by the judgment unit.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram of an insulation monitoring apparatus according to an embodiment of the present invention. The parts corresponding to the conventional example are designated by the same reference numerals as those in FIG.

This insulation monitoring device is provided with a timer 5 so that the monitoring time can be set, and if there is an alarm signal from the determination unit 4 within the set monitoring time, an alarm output is issued through the AND circuit 6. The insulation monitoring device body 7
Has the same configuration as the insulation monitoring device shown in FIG. 3 shown in the conventional example, and therefore the description of the insulation monitoring device main body 7 is omitted.

Hereinafter, the reason why the timer 5 is provided will be described with reference to FIG.

The horizontal axis of FIGS. 2A to 2C is the time axis. 2 (a) shows a temporal change of the system voltage, FIG. 2 (b) shows a temporal change of the noise level, and FIG. 2 (c) shows a temporal change of the partial discharge occurrence level. There is.

Since the actual system voltage fluctuates according to the load, as shown in FIG. 2 (a), the load is generally large during the daytime and therefore somewhat lower, and the load is small at midnight (2:00 am to 5:00 am). Tends to be somewhat higher. It can be seen that this is a general tendency even when looking at the load factor in industries and the like.

The load factor is also the load factor of the power supply equipment that is a noise source. That is, as shown in FIG. 2 (b), the noise level tends to decrease at midnight (2:00 am to 5:00 am). Therefore, if the timer 5 sets the monitoring time in a time zone where the noise level is low, the S / N is improved and malfunctions can be reduced.

Further, as shown in FIG. 2 (c), when partial discharge is occurring, there is a rise in the partial discharge occurrence level due to a rise in the system voltage at midnight (2:00 am to 5:00 am). Therefore, if the timer 5 sets the monitoring time in a time zone in which the partial discharge generation level is high, the S / N is improved and malfunctions can be reduced.

For example, the monitoring time may be set by the timer 5 from 2 am to 5 am, and if there is an alarm signal from the determination unit 4 within this time, an abnormality alarm may be output. Alternatively, the timer 5 may set the monitoring time from 3 am to 4 am, and if there is an alarm signal from the determination unit 4 for two consecutive days, an abnormal alarm may be output, or the main determination may be performed at 2 am From time to 5 o'clock, an initial warning may be issued by determining other time zones.

A spectrum analyzer may be used instead of the tuning amplifier 3.

[Effect of device]

In the insulation monitoring apparatus of the present invention, the timer outputs the alarm based on the alarm signal generated by the determination unit, so that the monitoring time of the insulation monitoring apparatus can be freely set. As a result, malfunction is caused by noise by setting the monitoring time of the insulation monitoring device to a fixed time zone at midnight when the noise level is low and the partial discharge generation level is high, for example, between 2 am and 5 am Can be prevented, and the accuracy of determining insulation deterioration can be increased.

[Brief description of drawings]

FIG. 1 is a block diagram of an insulation monitoring device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the reason why a timer is provided.
FIG. 3 is a block diagram of a conventional insulation monitoring device. 2 ... Antenna, 3 ... Tuning amplifier, 4 ... Judgment unit, 5 ... Timer

Claims (1)

[Scope of utility model registration request] 1. An antenna for detecting a wide-band electromagnetic wave that is secondarily generated when a partial discharge occurs, a tuning amplifier for performing narrow-band detection of the electromagnetic wave detected by the antenna except a part of the band, and the tuning. An insulation monitoring device comprising: a determination unit that determines the output of an amplifier and issues an alarm signal if it is abnormal; and a timer that issues an alarm output during a fixed time period at midnight based on the alarm signal.