Analysis on Lightning Strike Cause of Directly Buried Optical Cable in Wind Farm and Its Prevention Methods

Directly buried metal optical cable is a form of erecting optical fiber ring network communication system in wind farms. Although the directly buried optical cable is much less than the overhead optical cable affected by lightning, sometimes lightning damaging optical cable and flashover discharge accidents of optical cable port occurred. In this paper, the amplitude spectrum of lightning wave, the breakdown depth and breakdown distance of lightning wave to soil, the metal components of optical cable port and the impedance characteristics of grounding wire are systematically analyzed, and the prevention methods of directly buried optical cable in wind farm to avoid lightning damage are proposed.

Optical Cable Telecommunication Networks

1. Southern Coastal Optical Cable Engineering Project. The cable was completed and put into operation in 1992, and has a total length of 2,800km, starting from Nanjing in the north, via Shanghai, Hangzhou, Fuzhou, Xiamen, Huizhou, leading to Guangzhou in the south, covering Jiangsu, Shanghai, Zhejiang, Fujian and Guangdong. The whole line has

A New Optical Cable Communications Project

A key project of the state, the Beijing-Taiyuan-Xi’an optical cable communications trunk, is one of the 22 optical cables planned to be laid by the Ministry of Post and Telecommunications during the Eighth Five Year. Plan. This communication cable trunk covers a distance of 1771 km, starting from Beijing and going via Hebei and Shanxi to Xi’an in Shaanxi, linking two provincial capitals, one municipality directly under the jurisdiction of the central government, seven other cities and 32 counties.

全绝缘自支撑电缆系统设计(英文)

All-dielectric self-supporting(ADSS) cables are installed along with transmission line for the purpose of communication.During installation the outer layer of the cable is hydrophobic and is not prone to dry band arcing. These cables become less hydrophobic over time and become vulnerable to dry band arcing.This loss in hydrophobicity is because of the contamination formed on the outer layer due to pollution.This is one of the reasons which cause cable failure.Considerable amount of losses will be incurred on the occurrence of a cable failure as the cables are also leased to other companies.An improved equivalent circuit is used to calculate the voltage and current distribution of the double circuit line.A three-phase single circuit line and a three-phase double circuit line are used to calculate their corresponding voltage distribution and current distribution.The results could be used to predict dry band arcing on similar models.The method used considers sag,span and pollution on ADSS cable.

The Analysis of Angle Resolution of Stress Vector Sensor Based on Optical Fiber Sensing Cable for High Speed Railway Traffic

With the development of high speed railway traffic, the structure health monitoring for high-speed rail is necessary due to the safety issue. Optical fiber sensing technology is one of the options to solve it. Stress vector information is the important index to make more reasonable judgments about railway safety. However, information sensed by lots of commercial optical sensors is scalar. According to the stress filed distribution of rail, this paper proposes a new type of stress vector sensor based on optical fiber sensing cable(OFSC) with a symmetrical seven optical fibers structure and analyzes the relations between angle resolution and distance between adjacent of optical fibers through finite-element software(ANSYS) simulation. Through reasonable distance configuration, the angle resolution of the OFSC can be improved, and thus stress vector information, including the stress magnitude and the angle of stress, can be more accurately obtained. The simulation results are helpful to configure OFSC for angle resolution improvement in actual practice, and increase the safety factor in high speed railway structure health monitoring.

Application of Golay codes to distributed optical fiber sensor for long-distance oil pipeline leakage and external damage detection

A new distributed optical fiber sensor system for long-distance oil pipeline leakage and external damage detection is presented. A smart and sensitive optical fiber cable is buried beneath the soil running along the oil pipeline, which is sensitive to soakage of oil products and mechanical deformation and vibration caused by leaking, tampering, and mechanical impacting. The region of additional attenuation can be located based on the optical time domain reflectometry （OTDR）, and the types of external disturbances can be identified according to the characteristics of transmitted optical power. The Golay codes are utilized to improve the range-resolution performance of the OTDR sub-system and offer a method to characterize the transmitted optical power in a wide range of frequency spectrum. Theoretic analysis and simulation experiment have shown that the application of Golay codes can overcome the shortcomings of the prototype based on the conventional single-pulse OTDR.

An Accurate and Safe Small Raman Gain Measurement for Installed Fiber Optic Cables

Novel small Raman gain measurement method for installed fiber optic cables using a modulated pump light is proposed. We have demonstrated accurate Raman gain measurement in small Raman gain less than 1dB and we also measured Raman gain for the installed fiber optic cable by using average pumping power of about only 25mW.