Covered Conductor Burn-Down Phenomena in Indonesia without Protection Relay Operation

All Aluminium Alloy Conductor-Shielded (AAAC-S) which is covered conductor is widely used as the temporary solution to mitigate the earth fault problem during application of bare conductor in Indonesia distribution system. However, the burn-down phenomenon of AAAC-S is often found in some cases and the protection schemes that have been installed on the distribution line is unable to detect any fault during the phenomenon. Due to no tripping order from protection relay, this phenomenon will lead some part of the conductor remain hanging in the air and still in energized condition. This condition may cause a potential hazard to the surrounding environment. Therefore, this study was performed to determine the cause of AAAC-S burn-down and the reason of protection equipment cannot work properly. Field investigation, modelling and simulation, and laboratory testing has been performed in this study to represent the condition in the field. The results show that the burn-down phenomenon of AAAC-S occurred due to many sequences of events. It started with insulation material breakdown that create pinhole, then during overvoltage phenomenon there will be earth fault condition through the pinhole. Finally, if the short circuit energy at a certain mechanical tensile exceeds the critical energy of AAAC-S, then the burn-down phenomenon occurred. In this condition, the protection relay is unable to detect the fault due to the working time of protection relay is greater than the critical burn-down time of AAAC-S, where it is being influenced by the location of earth fault, cross-sectional area of AAAC-S, and grounding resistance of the pole

A case study of mutual current effect on circulating current protection system

Mutual impedance generated by the double circuit lines become such a challenge to be solved. Mutual induction arises when transmission line is a parallel line on a common right of way. In this study, a system model to observed mutual current effect on circulating current protection (CCP) system are explained. The system model is validated using actual recorded fault current waveform. In one and half breaker substation, the mutual current in maintenance line may cause CCP to pick up

A case study of mutual current effect on circulating current protection system

Mutual impedance generated by the double circuit lines become such a challenge to be solved. Mutual induction arises when transmission line is a parallel line on a common right of way. In this study, a system model to observed mutual current effect on circulating current protection (CCP) system are explained. The system model is validated using actual recorded fault current waveform. In one and half breaker substation, the mutual current in maintenance line may cause CCP to pick up

Covered conductor burn-down prevention for distribution line in Indonesia

Covered conductor (CC) is used to resolve temporary line to ground fault in the distribution line. However, some cases of CC burn down were found in Indonesia. These phenomena were triggered by lightning strikes that cause transient overvoltage with a magnitude greater than basic insulation level (BIL) of insulator. Consequently, short circuit current will flow through the pinhole on CC. Burn down phenomena will create high impedance fault that is unable to be detected by protection relay, thus the conductor will remain energized and harmful to the surroundings. Therefore, this paper presents study about CC burn down prevention. The study was performed using transient simulation to find the effect of earth wire utilization against the transient overvoltage due to lightning strike. In addition, finite element simulation and laboratory testing were also performed to analyze the effect of power arc device on burn down prevention. The results show that the lightning strike with negative polarity will not cause transient overvoltage with a magnitude greater than the insulator BIL. However, if the lighting strikes have positive polarity then the insulator BIL will be potentially exceeded. Furthermore, the utilization of power arc device will prevent the CC burn down

Investigation of transformer failure in Indonesia

Transformer failure investigation is important to obtain necessary actions which prevent similar failure from happening in the future. An investigation was conducted upon the failure of a transformer in Indonesia which damaged substation apparatuses nearby. To determine possible cause of the failure, the investigation was performed by doing visual inspection after failure, further analysis on related historical assessment result data and simulation using related nameplate and actual configuration. Most historical assessment result data showed no early failure indication of the transformer, while sweep frequency response analysis (SFRA) test result showed severe deformation on both primary and secondary winding. A simulation using Transient Analysis Program for internal short circuit between winding and ground was conducted and the output waveform was identical to Digital Fault Recorder (DFR) waveform data during transformer failure. Therefore, the possible cause of transformer failure was internal arcing on primary winding to ground which could not be interrupted by the protection system. According to visual inspection after failure, the possible cause of protection system malfunction was accidental open circuit in Current Transformer (CT) secondary circuit which damaged whole CT wiring

Covered conductor burn-down prevention for distribution line in Indonesia

Covered conductor (CC) is used to resolve temporary line to ground fault in the distribution line. However, some cases of CC burn down were found in Indonesia. These phenomena were triggered by lightning strikes that cause transient overvoltage with a magnitude greater than basic insulation level (BIL) of insulator. Consequently, short circuit current will flow through the pinhole on CC. Burn down phenomena will create high impedance fault that is unable to be detected by protection relay, thus the conductor will remain energized and harmful to the surroundings. Therefore, this paper presents study about CC burn down prevention. The study was performed using transient simulation to find the effect of earth wire utilization against the transient overvoltage due to lightning strike. In addition, finite element simulation and laboratory testing were also performed to analyze the effect of power arc device on burn down prevention. The results show that the lightning strike with negative polarity will not cause transient overvoltage with a magnitude greater than the insulator BIL. However, if the lighting strikes have positive polarity then the insulator BIL will be potentially exceeded. Furthermore, the utilization of power arc device will prevent the CC burn down

Investigation of transformer failure in Indonesia

Transformer failure investigation is important to obtain necessary actions which prevent similar failure from happening in the future. An investigation was conducted upon the failure of a transformer in Indonesia which damaged substation apparatuses nearby. To determine possible cause of the failure, the investigation was performed by doing visual inspection after failure, further analysis on related historical assessment result data and simulation using related nameplate and actual configuration. Most historical assessment result data showed no early failure indication of the transformer, while sweep frequency response analysis (SFRA) test result showed severe deformation on both primary and secondary winding. A simulation using Transient Analysis Program for internal short circuit between winding and ground was conducted and the output waveform was identical to Digital Fault Recorder (DFR) waveform data during transformer failure. Therefore, the possible cause of transformer failure was internal arcing on primary winding to ground which could not be interrupted by the protection system. According to visual inspection after failure, the possible cause of protection system malfunction was accidental open circuit in Current Transformer (CT) secondary circuit which damaged whole CT wiring

Effect of indirect lightning strike to 66kV transmission line in Java-Bali system

Based on Java-Bali grid disturbance data, the 66kV transmission lines that is close to or intersect with 150kV or 500kV transmission line is often experienced earth fault due to insulator flashover. The insulator flashover can be caused by indirect lightning strike since lightning strikes tend to strike higher structure. Therefore, this paper will determine the effect of indirect lightning strike on 150kV or 500kV transmission line to 66kV transmission line by modeling and simulation using application of transient analysis. Variation of lightning peak current magnitude and gap between 66kV transmission line and transmission line with higher voltage is performed during simulation. The range of peak current magnitude follows the data from lightning detection systems, while the value of gap follows the data from actual condition. It is found that higher current peak and closer gap will cause higher transient overvoltage on insulator of 66kV transmission line thus insulator flashover may occur more frequent. Addition of earth wire on 66kV transmission line and gap between each transmission by organizing the sag of conductor can be performed to minimize the insulator flashover