Multi functional energy meters have functions like pressure loss, flow loss, voltage qualification record, alarm, display, and other functions, which can effectively prevent leakage. And the GPRS module (built-in or external), wireless module, and GSM modules can be installed according to the needs of the user to solve the remote problem and expand the function of the metering channel. Its advantages are that the circuit design and component selection are based on environmentally permitted errors, which can ensure the long-term stable operation of the multi function energy meters. In particular, its accuracy is basically not influenced by changes in frequency, temperature, and voltage. The reliability is significantly improved compared with other similar products.