The through-core transformer is used, which is completely isolated from the secondary circuit and has high safety It adopts distributed measurement structure, namely on-site measurement and digital transmission, and the protocol complies with DL/T860 standard It can be installed with electricity, that is, it does not need to install the main equipment without power failure, and it is convenient and fast to access the system Using digital filtering methods to eliminate the "zero drift problem" caused by analog filters Using high-precision active zero magnetic flux sensor, intelligently select the conditioning circuit and magnification according to the magnitude of the measured current, which effectively improves the measurement accuracy With on-site real-time temperature and humidity measurement function