• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
• /
• pp.975-979
• /
• 2001

In connection with the monitoring of the insulation degradation of large power apparatus in order to predict their expected service failures, a statistical treatment, such as phase resolved partial discharge analysis (PRPDA), has been established for the on-line monitoring system during the past decades. However, this method has shown some inconveniences to identify the nature of the PD source in power apparatus. In this regard, a novel approach based on the chaotic analysis (CAPD) is proposed describing the fundamental ideas, outcomes and different viewpoints from the conventional PRPDA. As a model for the possible defects causing sudden failures in service, three types of specimen are prepared. And partial discharge signals, originated from those samples, are measured and analyzed by means of CAPD. Throughout this work, it seems that the correlation between the consecutive PD pulses, depending on the nature of PD, could be clarified by CAPD. Thereffre, it could be considered that the nature of PD source can be identified more distinctively when the CAPD is combined with PRPDA.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권6호
• /
• pp.324-329
• /
• 2004

Six stator slot couplers(SSC) and a flux probe sensor installed on the stator winding slots of large turbine generator. Assessment of insulation condition has been based upon the measurements of partial discharge(PD) of stator windings and shorted-turn of rotor windings in operating large turbine generator. The maximum PD magnitude(Qm), normalized quantify number(NQN), PD pattern and shorted-turn were measured using on-line insulation condition monitoring system. The NQN and Qm of slot PD side in the phase A are indicated the highest value in six SSC sensors. Monitoring system results showed that discharge at conductor surface and internal discharge were detected at the surface of stator winding and in voids of the groundwall insulation. Insulation of stator and rotor windings in large turbine generator was judged to be in good condition.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.224-226
• /
• 2001

In this paper, a novel high-voltage motor monitoring system (HVMMS) is proposed. This system monitors the insulation condition of the stator winding by on-line measurements of partial discharge (PD). Sensor, EMC (Epoxy-Mica Coupler) is used for PD measurement PD signals are continuously measured and digitized with a peak-hold A/D converter to build the database of the high-voltage motor's insulation condition. Also, this system can communicate with the central monitoring system via RS-485. This helps more efficient operation and maintenance of the generator.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
• /
• pp.95-96
• /
• 2008

We constructed an on-line PD monitoring system for the 380kV U/G Cable project at the Riyad 9012 substation in Saudi-arabia. The system will be monitoring the termination of the two 380kV XLPE Cables to prevent unexpected failure of the cable insulation. The system had been tested in the laboratory and on-site for detection of various PD signals and reliability of operation. The system distinguish the existence and nonexistence of the partial discharge and then judge the source of partial discharge using automatic PD pattern recognition software.

• Bulletin of the Korean Chemical Society
• /
• 제24권3호
• /
• pp.291-294
• /
• 2003

A highly interferent-resistive membrane, poly-5-amino-1-naphthol (poly-5A1N), underlied beneath enzymeembedded poly-1,3-phenylendiamine (poly-m-PD) network for miniturized continuous monitoring glucose sensors. The enzyme layer was prepared from a mixed solution of glucose oxidase (GOx) and m-PD monomer by simple electrolysis. The mass change of poly-5A1N was monitored by electrochemical quartz crystal microbalance (EQCM) in situ and the corresponding thickness was measured. Successive electropolymerization of poly-5A1N and poly-m-PD create a several tens nm-thick bilayer showing excellent selectivity for $H_2O_2$ and low activity loss of immobilized enzymes.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권4호
• /
• pp.460-466
• /
• 2004

This study was undertaken with the aim to establish a reliable radioimmunoassay (RIA) system for urinary pregnanediol glucuronide (PdG) and to employ it for monitoring the reproductive status of dairy cows. Urine and blood samples were collected from the Holstein cows both pregnant and non-pregnant. The samples were then investigated for evaluating the relationship between progesterone ($P_{4}$) in blood and PdG in urine adjusted with or without urinary creatinine basis. Biweekly urine collection was employed for three cows in estrous and those artificially inseminated, while urine from pregnant cows was collected on a monthly basis. P_{4}$ and PdG levels were measured by enzymeimmunoassay (EIA) and RIA techniques, respectively. Our results indicated the sensitivity of PdG for RIA being 35 pg/tube and the recovery rate of 100%. Urinary creatinine concentrations also fluctuated within a day, but change at midday was not noteworthy. Regardless of the time of urination the change in concentrations of PdG was relatively smaller and did not vary significantly. The urinary PdG concentration showed periodic changes as that with serum P_{4}$ levels during the cow's estrus cycle. The correlation coefficient rose when creatinine level in urine was adjusted but the change was also not significant. The concentrations of PdG during the luteal phase were detected between 8.2 and 17.4 ng/ml, three to five times higher than that in the follicular phase. The concentration of PdG from pregnant cows (21 days after conception) was three to four times higher than in the nonpregnant cows. Our finding suggests that the determination of urinary PdG could be reliably employed for early pregnancy detection. The urinary PdG level continued to raise until 30 days pre-partum while the concentration reached its peak at 30 ng/ml, after which it started to fall 18 to 30 days before parturition and finally fell to its nadir value one week after parturition. As the correlation coefficient between the urinary PdG and serum P_{4}$ was higher than that corrected by urinary creatinine it can be suggested that the adjustment is not needed. The concentrations of urinary PdG could be maintained stably for 2 days in urine samples stored at room temperature and extended to 8 days when the samples were pretreated by boiling for 30 minutes. In conclusion urinary PdG concentration even without the need for creatinine basis adjustment can be used directly for monitoring the reproductive status of dairy cows.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권3호
• /
• pp.168-174
• /
• 2004

On-line monitoring system(OMS) has been developed for the pumped storage generator/motor The OMS is applied to diagnosis of the PD(partial discharge) activity of stator insulation, the shorted-turn of rotor winding and the variation of the air-gap between stator and rotor. The OMS consists of DAS(data acquisition system), main server system, gateway and display PC. The DAS measures the PD, the shorted-turn and air-gap from three sensors installed on the generator/motor. The gateway controls the data which sent by DAS. The main server system saves the data, analyzes the data and conducts the diagnostic algorithm. The display PC shows the diagnostic results of partial discharge, shorted-turn and air-gap. Field tests were conducted using PDA(partial discharge analyzer). The results of the OMS and PDA measurements can be directly correlated with normalized quantity number(NQN), PD magnitude(Qm) and PD pattern.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
• /
• pp.481-486
• /
• 2006

In this paper, a new on-line high-voltage motor monitoring system is proposed. This system monitors the insulation condition of the stator winding by on-line measurements of partial discharge (PD). And this system displays magnitude and phase angle distribution of PD. Sensor, CC (Ceramic Coupler) is used for PD measurement. PD signals are continuously measured and digitized with a A/D converter to build the database of the high-voltage motor's insulation condition. Also, this system can communicate with the central monitoring system via RS-232, 422, and TCP/IP. This helps more efficient operation and maintenance of the high-voltage motor.

• KIEE International Transactions on Power Engineering
• /
• 제4A권1호
• /
• pp.33-41
• /
• 2004

Knowledge of partial discharge (PD) is important to accurately diagnose and predict the condition of insulation. The PD phenomenon is highly complex and seems to be random in its occurrence. This paper indicates the possible use of chaos theory for the recognition and distinction concerning PD signals. Chaos refers to a state where the predictive abilities of a systems future are lost and the system is rendered aperiodic. The analysis of PD using deterministic chaos comprises of the study of the basic system dynamics of the PD phenomenon. This involves the construction of the PD attractor in state space. The simulation results show that the variance of an orthogonal axis in an attractor of chaos theory increases according to the magnitude and the number of PDs. However, it is difficult to clearly identify the characteristics of the PDs. Thus, we calculated the magnitude on an orthogonal axis in an attractor using singular value decomposition (SVD) and principal component analysis (PCA) to extract the numerical characteristics. In this paper, we proposed the condition monitoring method for gas insulated switchgear (GIS) using SVD for efficient calculation of the variance. Thousands of simulations have proven the accuracy and effectiveness of the proposed algorithm.

• E2M - 전기 전자와 첨단 소재
• /
• 제11권11호
• /
• pp.1-8
• /
• 1998

This paper presents an arificial neuro-fuzzy technique based prtial discharge (PD) pattern classifier to power system application. This may require a complicated analysis method employ -ing an experts system due to very complex progressing discharge form under exter-nal stress. After referring briefly to the developments of artificical neural network based PD measurements, the paper outlines how the introduction of new emerging technology has resulted in the design of a number of PD diagnostic systems for practical applicaton of residual lifetime prediction. The appropriate PD data base structure and selection of learning data size of PD pattern based on fractal dimentsional and 3-D PD-normalization, extraction of relevant characteristic fea-ture of PD recognition are discussed. Some practical aspects encountered with unknown stress in the neuro-fuzzy techniques based real time PD recognition are also addressed.