Design On Predict And Alarm System For Power Cable Ampacity Based On GPRS

Electrical power cable is one of the basic components of the power system, its operational reliability affect the safe operation of the entire system. A large number of scholars at home and abroad work on the current carrying capacity of cable, and various monitoring methods are proposed. In this paper, a predict and alarm system for power cable ampacity based on GPRS is designed to monitor the ampacity of cable. The temperature of power cable wire core can be monitored by the predict and alarm system, while the remaining ampacity of cable can be predicted, which provide the judgment of the grid operation status for the grid staff.First of all, the research methods of the power cable are analyzed. The ampacity of cable is monitored by the predict and alarm system used the cable international standard IEC60287as a theoretical basis. The impact of cable heat conduction produced by cable insulation structure is researched, and the formula of the the current carrying capacity of cable is derived.Secondly, a predict and alarm system for power cable ampacity based on GPRS is designed. Each block and its peripheral circuits of predict and alarm system are given in detail, and the working mode of various blocks is described. Remote data transfer is realized based on GPRS, the measured data is sent to the upper computer for processing. The temperature of power cable wire core and the remaining ampacity of cable can be predicted.Finally,10kV XLPE cable loading run under air laying environment is simulated in the lab. The cable sheath temperature and operating current are monitored by the system to predict the temperature of power cable wire core and the remaining current carrying capacity of cable. Using the resistance of cable line core measured by DC resistance measuring instrument, the temperature of power cable wire core derived according to the resistance formula is compared with the temperature of power cable wire core measured by the predict and alarm system. Experiments show that the measurement error of predict and alarm system is small, and the predict and alarm function of the ampacity of cable can be achieved.