• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.950-958
• /
• 2017

Viaduct increases the height of subway catenary, namely magnifies lightning attraction scope that lead to higher possibility of suffering lightning stroke. Therefore, it is necessary to analyze performance of lightning striking to catenary of subway in viaduct section and propose an improving lightning protection scheme. In this paper, using ATP-EMTP simulation software to establish an associated model to evaluate lightning withstand level of catenary with existing lightning protection schemes including arrester and grounding point, an improving lightning protection scheme is proposed - every pillar ground earth and arresters are installed with some installing spacing between 200m to 400m based on lightning damage degree and reliability requirements - according to analyzing results: while lightning withstand level is lowest for lightning striking to the neutral pillar, lightning withstand level is greatest for lightning striking to the both-ends pillar that arrester and grounding point are both installed; grounding point could obviously improve lightning withstand level for lightning striking to ground wire while arrester could obviously improve the lightning withstand level for lightning striking to catenary; every pillar ground earth could enhance the lowest lightning withstanding level up to 2.5 times than of that pillar ground earth across every 200m.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.3C no.3
• /
• pp.91-98
• /
• 2003

The importance of improving the quality of electric power is being strongly raised, owing to an increasing use of sensitive and small-sized electronic devices and systems. The transient over-voltages on low-voltage power distribution systems are induced by direct or indirect lightning return strokes. These can cause damage and/or malfunction of the utility systems for home automation, office automation, factory automation, medical automation, etc. The behaviors of lightning overvoltages transferred through the transformer to the low-voltage distribution systems using a Marx generator were experimentally investigated. Furthermore, the coupling mechanisms of lightning overvoltages transferred to the low-voltage systems were clearly illustrated through a theoretical simulation using a Pspice program. The overvoltages in low-voltage ac power systems are rarely limited by the application of the surge arrester to the primary side of the distribution transformer. A superior surge protection scheme is to install surge protection devices at the service entrance switchboard and/or at the load devices in TN power systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.2
• /
• pp.78-85
• /
• 2012

Low-Voltage power lines should equip surge protection devices which protect electronic equipments and human lives against lightning and abnormal voltages. Data transmission capacity of the power line is determined by frequency characteristics of the surge protective devices. To analyze the effects of surge protective devices on the data transmission performance, various combinations of installation methods are tested which include ZnO varistor elements that is compatible with class I, class II and class III. The result claims that ZnO varistor for class III is found to be one of the main factors that deteriorates the transmission performance. To overcome this problem a serial connection methed between Gap type SPD and ZnO varistor is proposed. With the proposed scheme, laboratory experimental results show that the data transmission performance can be improved up to 91.9[%] with proper SPD combination.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.7
• /
• pp.421-428
• /
• 2003

After the cable is installed, many geometric factors, such as bowing types of the cable and the length difference of the cable between each minor section will cause the impedance unbalance between cables. The impedance unbalance will increase or decrease the sheath circulating currents, which are critical to human safety and sustaining the capabilities of electric power. Accordingly, in this paper, a new method is also proposed to reduce the sheath circulating currents and an reduction equipment according to the theory of the new method is developed. The reduction equipment is tested when the cable is on service. The test results show that it can reduce the sheath circulating currents by up to 97.8［%］. This confirms the validation of the new method and the reduction equipment, and assures the safe operation of the transmission cables. In order to illustrate the safe operation of the cable with new current reduction equipment at transient state due to lightning and single line-to-ground fault, extensive simulations have been made. Then the protection scheme of sheath circulating currents reduction equipment is proposed by adopting the new device of RDP(Reduction Device Protector).