On-line Fault Monitoring And Early-warning System For Power Cable Joints In City Zone

Power cable joint is a weak link of the safe of power grid. It is a long time from overheating to fire accidents. The on-line monitoring of power cable joints temperature can prevent and reduce joints accidents effectively. The current on-line monitoring systems for power cable joints have some disadvantages such as difficulty of the power supply of detecting devices, the restricted distance of data transmission and the high cost of devices. Because of the disadvantages, they are just suitable for the transformer substation or the power plant.Taking the key science and technology planning project of NEG (the urban power cable joints safety fireproof remote online monitoring system) as engineering background, according to the characteristics with large quantity and extensive locations of power cable joints in urban districts, a new type of on-line fault monitoring and early-warning system was developed in this paper. The monitoring system is composed of slave machine, wireless network and master machine management system. Low consumption microcontroller C8051F020 as a data acquisition terminal, Wavecom Q2406A as data transfer equipment. The PC software has the following functions, temperature remote monitoring, early alarming, warning and state assessment of power cable joints. Furthermore, GIS function was realized based on MAPX component and data transmission by GSM/GPRS network.Aiming at the difficulty in the power supply of monitoring device, a new type of power supply device was designed and developed based on supercapacitor, that is obtained power directly from the power line by tailor-made current transformer ,it can solve the difficult point effectively.The monitoring system is especially adequate to big and medium city. The equipment has been practically applied with good effect.