In order to improve the precision and anti-interference capacity of on-line tan δ monitoring system for capacitive apparatus

a high precision tan δ monitoring system is presented. The injecting signal produced by FPGA is used to realize the functions such as error adaptive correcting and the signal producing for measurement of dielectric loss. Then the tan δ is calculated by combining the integrated techniques of signals with the zero cross point comparing method. The results of experiment and field tests show that the interference of power system in power frequency can be avoided and also the inherent measuring errors of hardware can be eliminated. Thus the precision and stability of this system proposed are verified much better than those of the traditional measuring equipment.