JPH03110487A - Detector for partial discharge - Google Patents

Abstract

PURPOSE:To reduce an error contained in detected data and to improve a reliability by making it possible to convert a detected high frequency signal to a pulse signal having an optional time width. CONSTITUTION:When a partial discharge is generated on a center conductor 3 in a metal casing 2, high frequency components generated due to this discharge are superimposed to a voltage on both ends of a capacitor 5. Then, once passing through a peak holding circuit or integration circuit 14, they are inputted to a V/F conversion part 15 after converted further to the pulse P3 having the pulse width on the order of 0.1-0.5 ms, thereby a frequency modulation is made possible for the detected partial discharge. The V/F converted signal is converted to an optical pulse signal by an E/O conversion part 16 and outputted to a receiver 18 through an optical fiber 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a partial discharge detector that measures partial discharge generated in high voltage equipment such as a closed gas switch or a transformer.

(Prior art) Fig. 4 shows a sealed bus bar connected to a general sealed gas insulated switch.The metal casing 1 has a high-voltage section that is open and is electrically connected to a power transmission line (not shown) at its center. A center conductor 3 is insulated and supported by a spacer 2.

The casing 1 is grounded by a grounding wire (not shown).

The spacer 2 is provided with an electrode 4 for voltage detection, and between this electrode and the casing 1 and the conductor 3, stray capacitances C2 and C1 exist, and this stray capacitance C2 is shown as a capacitor 5. A detector 7 is connected to both terminals of the capacitor 5 via a signal lead-in line 6 .

When a high voltage is applied to the center conductor 3, the stray capacitance C1 existing between the center conductor 3 and the electrode 4 and the capacitor 5 constitute a voltage divider.

Therefore, when a partial discharge occurs in the middle of the central conductor in the metal casing 1, a high frequency component (signal) caused by the discharge is superimposed on both ends of the capacitor 5, and this high frequency signal is detected by the detector 7. After being detected separately from the shared voltage and amplified by the amplifier 8, the E/O converter 9
The signal is transmitted in the form of an optical signal to a monitoring unit (not shown) via the optical fiber /O of the transmission path. Therefore, it is possible to detect the occurrence of partial discharge within the sealed bus bar using this high frequency signal.

(Problems to be Solved by the Invention) In the partial discharge detector 7 as described above, the detected partial discharge signal is transmitted to the upper system as an optical analog signal by the F/O converter 9. However, normally, the light intensity of the light emitting element (e.g. light emitting diode) used in the E/O converter 9 decreases over time. This has the disadvantage that the error included in the detected data becomes large.

An object of the present invention is to provide a highly reliable partial discharge detector.

[Structure of the invention]

(Means for Solving the Problems) The partial discharge detector of the present invention converts an output signal from a bandpass filter that detects a signal in a specific frequency band into a pulse signal having an arbitrary time width, and then modulates the local frequency. It is characterized in that it is output as an optical signal.

(Function) In the present invention, by converting the detected high frequency signal into a pulse signal having an arbitrary time width, data can be frequency modulated and output as an optical signal. Further, by setting the time width of the pulse to 0.5+ss or less, it becomes possible to analyze the phase of partial discharge occurrence.

(Example) The present invention will be described based on an example shown in FIG. An insulating spacer 2 and a center conductor 3 are housed in a metal casing 1. Stray capacitances C1 and C2 generated between the voltage detecting electrode 4 buried in the insulating spacer 2 and the conductor 3, etc.
is used to detect high-frequency signals generated by partial discharges occurring at arbitrary locations on the center conductor 3. The detected high frequency signal is separated by a coil 11 and sent to the subsequent electronic circuit section.

First, a signal in a specific frequency band (for example, several/OMHz) is extracted from the high frequency signal by the band pass filter 12,
After being amplified by the amplifier 13, the signal is input to the peak hold circuit 14 provided in the present invention. Furthermore, V/F conversion circuit 1
5, the detection signal is modulated, outputted as an optical signal by the E/O conversion circuit 16, and sent to the receiver 1 through the optical fiber 17.
It is configured to be sent to 8.

Next, the operation of the partial discharge detector of the present invention constructed as described above will be explained with reference to FIGS. 1, 2, and 3.

In FIG. 1, when a partial discharge occurs in the center conductor 3 in the metal casing 1, a high frequency component generated due to the discharge is superimposed on the voltage across the capacitor 5. A bandpass filter 12 separates and detects specific frequency components (for example, several/OMHz) of this high frequency signal.

The signal waveform at the capacitor 5 is like the corona signal P1 shown in FIG. 2(a), and the signal waveform after the bandpass filter 12 is like the waveform P2 in FIG. 2(b).

As shown in the figure, these signal waveforms are generated within several Ons and have high frequencies, so they are directly connected to the V/F converter 15.
Even if input to
) with a pulse width of about 0.1 to 0.56,
By converting the detected partial discharge signal into the V/F converter 15, it becomes possible to frequency-modulate the detected partial discharge signal. The V/F converted signal is converted into an optical pulse signal by the E/O converter 16, and is sent to the receiver 1 via the optical fiber 17.
8.

Furthermore, since the pulse has a time width of about 0.1 to 0.5 ms, it is also possible to measure the degree of occurrence in each phase when the partial discharge shown in Fig. 3A occurs, as shown in Fig. 3B. becomes.

As explained above, in this embodiment, after amplifying the signal that has passed through the bandpass filter 12, the signal is input to the peak hold circuit 14 and then converted into a pulse width that can sufficiently track one frequency modulation and also enable phase analysis. By this,
It is possible to provide a highly accurate and more reliable partial discharge detector for detecting high frequency components generated by partial discharge and transmitting them as optical signals.

〔Effect of the invention〕

As explained above, in the present invention, after amplifying a signal that has passed through a bandpass filter and inputting it to a park hold circuit or an integrating circuit, the signal is converted into a pulse width that can be sufficiently followed by frequency modulation and further allows phase analysis. According to
It is possible to provide a highly accurate and more reliable partial discharge detector for detecting high frequency components generated by partial discharge and transmitting them as optical signals.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the partial discharge detector of the present invention, FIG. 2 is a signal waveform diagram of the components shown in FIG. 1, and FIG.
The figure is a waveform diagram of a high frequency signal caused by the conductor and partial discharge shown in FIG. 1, and FIG. 4 is a configuration diagram showing a conventional partial discharge detector. 1... Metal casing 2... Insulating spacer 3.
... Center conductor 5 ... Capacitor 7 ... Detector 9 ... E/O converter 11 ... Coil 13 ... Amplifier 15 ... V/F conversion circuit 17 ... Optical fiber 4 ... Electrode for voltage detection 6 ... Signal lead-in line 8 ... Amplifier/O ... Optical fiber 12 ... Band pass filter 14 ... Peak hold circuit 16 ... E/O conversion circuit 18 ...Receiver (8733)

Claims (1)

[Claims] A device that detects partial discharges that occur in high-voltage equipment includes a bandpass filter that detects signals in a specific frequency band from among high-frequency signals generated due to partial discharges, and an arbitrary output signal from this bandpass filter. a peak hold circuit or an integrating circuit that converts the output signal into a pulse signal having a time width of A partial discharge detector characterized by comprising: