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1. 发明专利

JPH04331381A CALIBRATING METHOD OF PARTIAL DISCHARGE MEASUREMENT 失效
公开(公告)号：JPH04331381A
公开(公告)日：1992-11-19
申请号：JP4136991
申请日：1991-01-10
申请人： TOKYO ELECTRIC POWER CO , HITACHI CABLE
发明人： KATSUTA GINZO , TOTANI ATSUSHI , ENDO TAKESHI , SUZUKI HIROSHI , IMAI TOMOAKI , HAGITANI MIKIO
IPC分类号： G01R31/12
摘要： PURPOSE:To perform correctly the calibration of the partial discharge measurement of a power cable in hot-line state by injecting a calibration pulse into a direct detection system, detecting the calibration pulse by a measurement system, and making not affected by the attenuation of the calibration pulse. CONSTITUTION:A partial discharge measurement equipment 25 is connected into the grounding cable 23 of a sheath 22 of a power cable 20. A calibration pulse oscillator 27 is conneted parallel to the measurement equipment 25, and the detecting sensitivity of the calibration pulse is found by the measurement system containing several impedances of a characteristic impedance 26 between a high voltage conductor 21 of the cable 20 and the sheath 22, a ground impedance 28 between the grounded sheath 22 and the ground, and a coupling impedance 27 between the high voltage conductor 21 and the ground. The calibration of a partial discharge measurement of the power cable 20 is very correctly performed without being affected by the attinuation of the pulse occurring when the calibration pulse is propagated through the power cable 20, by connecting the calibration pulse oscillator 27 parallel to a detection system, injecting the calibration pulse into the direct detection system, and detecting the calibration pulse by the measurement system.

2. 发明专利

JPH03245070A METHOD FOR MEASURING PARTIAL DISCHARGE 失效
公开(公告)号：JPH03245070A
公开(公告)日：1991-10-31
申请号：JP4217590
申请日：1990-02-22
申请人： TOKYO ELECTRIC POWER CO , HITACHI CABLE
发明人： KATSUTA GINZO , TOTANI ATSUSHI , ENDO TAKESHI , HAGITANI MIKIO , IMAI TOMOAKI
IPC分类号： G01R31/12
摘要： PURPOSE:To measure partial discharge with high sensitivity by discriminating between a partial discharge pulse and noise by observing the waveform of the output signal obtained by the first method when an output signal exceeding a predetermined level is obtained by the measurement due to the second method. CONSTITUTION:The detection signal obtained from a circuit using a coupling condenser 2 and a detection impedance 3 is processed by the first method to perform the observation of a waveform. Next, the detection signal obtained from the circuit using the coupling condenser 2 and the detection impedance 3 is processed by the second method. That is, the signal obtained from the detection impedance 3 is inputted to a tuning circuit 8 having predetermined tuning frequency. When the signal has the frequency component coinciding with the tuning frequency, said component is detected as a tuning signal. Subsequently, the waveform of the output signal obtained by the second method is observed when an output signal exceeding a predetermined level is obtained by the measurement due to the second method. By this method, a partial discharge pulse and noise can be discriminated by observing the waveform of a pulse high in the possibility of the partial discharge pulse.

3. 发明专利

JPH04215076A PARTIAL DISCHARGE MEASURING METHOD 失效
公开(公告)号：JPH04215076A
公开(公告)日：1992-08-05
申请号：JP41017090
申请日：1990-12-12
申请人： TOKYO ELECTRIC POWER CO , HITACHI CABLE
发明人： KATSUTA GINZO , TOTANI ATSUSHI , ENDO TAKESHI , SUZUKI HIROSHI , IMAI TOMOAKI , HAGITANI MIKIO , MARUMO MORITADA
IPC分类号： G01R27/18 , G01R31/12
摘要： PURPOSE:To measure the partial discharge of a high voltage insulated device, connected to a high voltage cable, in a live line state simply and with high sensitivity by employing a measuring system containing electrostatic capacitance of a power cable as a coupling capacitor. CONSTITUTION:A sheath 36 of a power cable 30 is earthed in the vicinity of the end part of the cable through an earthing line 37, a high frequency core 38 is mounted on the earthing line 37, and a partial discharge detectors 40 is connected to the both ends of the frequency core through an impedance 39. Since a partial discharge pulse is detected by a measuring system containing the power cable 30 as a coupling capacitor, a partial discharge pulse can be detected with a relatively low damping factor through utilization of the earthing line 37. Since noise is damped in a process where the noise is propagated through the cable 30, a noise level in a measuring spot is decreased. A relation between the pulse waveform of a detecting partial discharge pulse and an applied voltage phase and relation with a pulse polarity are determined, and from the relations, a region where the partial discharge pulse is generated can be specified.

4. 发明专利

JPH0619413B2 失效
公开(公告)号：JPH0619413B2
公开(公告)日：1994-03-16
申请号：JP31576688
申请日：1988-12-14
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , HAGITANI MIKIO , IKEDA TADAYOSHI
IPC分类号： G01R31/12

5. 发明专利

JPH068846B2 失效
公开(公告)号：JPH068846B2
公开(公告)日：1994-02-02
申请号：JP30974389
申请日：1989-11-29
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , IMAI TOMOAKI , HAGITANI MIKIO
IPC分类号： G01R31/12

6. 发明专利

JPH068847B2 失效
公开(公告)号：JPH068847B2
公开(公告)日：1994-02-02
申请号：JP30974489
申请日：1989-11-29
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , IMAI TOMOAKI , HAGITANI MIKIO
IPC分类号： G01R31/12

7. 发明专利

JPH03170077A PARTIAL DISCHARGE MEASURING METHOD FOR WIRE SHIELD CABLE 失效
公开(公告)号：JPH03170077A
公开(公告)日：1991-07-23
申请号：JP30974489
申请日：1989-11-29
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , IMAI TOMOAKI , HAGITANI MIKIO
IPC分类号： G01R31/12
摘要： PURPOSE:To measure partial discharging pulses with a high SN ratio and high sensitivity by providing a coil outside the cable which is shielded with a wire shield and measuring the partial discharging pulses by the electromagnetic coupling between the wire shield and the coil. CONSTITUTION:Both ends of a detection coil 8 wound around the cable 1 to be tested are connected to detection impedance 5 and a pulse measuring instrument 7 is connected across the detection impedance 5. Then a pulse generator 31 is connected between the internal conductor and sheath of the cable to be tested. While no electricity is applied to the cable 1 and no pulse is applied from the pulse generator 31, namely, in a state wherein there are only noises, and in a state wherein calibration pulses of 20pC are applied from the pulse generator 31, the frequency dependency of the detection output of a detection 8 is found. In this case, the highest detection sensitivity is obtained at about 11MHz and the effect of applied pulses is hardly recognized below about 7MHz.

8. 发明专利

JPH03170076A PARTIAL DISCHARGE MEASURING METHOD 失效
公开(公告)号：JPH03170076A
公开(公告)日：1991-07-23
申请号：JP30974389
申请日：1989-11-29
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , IMAI TOMOAKI , HAGITANI MIKIO
IPC分类号： G01R31/12
摘要： PURPOSE:To obtain high detection sensitivity by selecting a measurement frequency at which an SN ratio becomes as high as possible by calibrating the detection sensitivity with calibration pulses and measuring partial discharging pulses at the frequency. CONSTITUTION:A coupling capacitor 3 and detection impedance 4 are connected between a high voltage conductor connected to a high voltage application terminal 2 and the ground and a measuring instrument 5 is connected in parallel to the detection impedance 4. The frequency spectrum of a detection signal is found by this circuit while no electricity is applied to the cable 1 and a pulse generator 6 is not in operation, namely, in a state wherein only noises are present. Then the pulse generator 6 is put in operation and calibration pulses of 100pC are applied from the pulse generator 6. In this state, the frequency dependency of the detection pulses is found by using the spectrum analyzer of the measuring instrument 5. Those two cases are compared with each other to know that noises are reduced greatly between 4.5 and 5.5MHz and the SN ratio becomes high between 4.8 and 10MHz eventually.

9. 发明专利

JPH02161369A MEASURING METHOD FOR PARTIAL ELECTRIC DISCHARGE 失效
公开(公告)号：JPH02161369A
公开(公告)日：1990-06-21
申请号：JP31576688
申请日：1988-12-14
申请人： HITACHI CABLE
发明人： ENDO TAKESHI , HAGITANI MIKIO , IKEDA TADAYOSHI
IPC分类号： G01R31/12
摘要： PURPOSE:To measure the partial electric discharge with high accuracy by prescribed S/N by selecting a measuring frequency from in a specific frequency band and measuring the partial electric discharge of a long-sized power cable having a terminal connecting part and an intermediate connecting part. CONSTITUTION:A conductor 1 is connected through a connecting sleeve 2, and the conductor 1 is covered with cross-link polyethylene 3. On the outside periphery of the polyethylene 3, an external semiconductor layer 4 is provided, and on its outside periphery, a metallic sheath 4 is provided. A sheath 5 is eliminated by prescribed length in the middle part of a metallic drum pipe 7, and a detection impedance 8 is connected to the sheath 5 therein, and also, provided so as to come into contact with the layer 4. One end of the impedance 8 is connected to an internal conductor of a coaxial cable 9. This cable 9 is connected to a measuring instrument 10 having a frequency band of 20 - 1,000MHz. In such a way, by selecting the measuring instrument 10 of a resistance value corresponding to the determined detection impedance, a high frequency pulse based on the partial electric discharge is detected by prescribed S/N.

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