On-Line Monitoring of Cable Trench and Cable Pit by Using Metal Armored FBG Temperature Sensors

Substation cable trench and cable pit lay many cables, which are used to connect electrical equipment. The longrunning of cable will probably cause insulation material aging, leakage sparking and local overheating occur, which eventually lead to a cable fire, the temperature of cable surface usually reflected the situation of the cable. Metal armored fiber Bragg grating temperature sensor are applying in a substation cable trench and cable pit, with four fiber trench it monitor the 60 cable temperature measuring point in current time. The 24-hours real-time monitoring indicates that the temperature of morning is the minimum, and the temperature of afternoon is the maximum. The temperature of cable surface ranges in the similar curve with ambient temperature. In the long-term of 479 days, the minimum of the average daily temperature range of 60 sensors is 21.24℃,detected at number 9 trench 1, The maximum is 37.43℃,detected at number 4 trench 2, which reached its maximum temperature 43.41℃ on July 3, 2010, and the minimum temperature is 4.37℃ on January 17, 2011,number 13 trench 1. The temperature of sensors changed in the same trend with seasons.