Electronic energy meter power supply - operates with sampling circuit for checking and regulating output voltage

摘要

The application is to power supplies for energy meters, for example watt hour meters or devices for measuring thermal energy, which employ electronic circuits. The power supply is composed of a switching circuit (N) whose output is at high frequency and typically sinusoidal. It incorporates a regulating circuit, preferably based on a sampling system, which compensates for variations in the primary supply from the system (R,S,T). The mains voltage is provided with surge arresters (B, Cp) and a clipping capacitor (CL) after the rectification stage. Spike diverting capacitors may also be added to the output of the switching circuit (N). These devices ensure that no fast transients get through to the electronic circuits. By dropping the mains supply through series resistors (RV) low voltage switching transistors can be used in the switching circuit (N). This gives increased life and reliability.