Electronic electric-energy meter

An electronic electric-energy meter for measuring a kind of electric energy carried on power lines, said meter comprising:

• a. a voltage transformer connected to said power lines for producing a voltage signal proportional to a load voltage on said power lines;
• b. a current transformer connected to said power lines for producing a current signal proportional to a load current on said power lines;
• c. a pulse width modulation circuit connected to said current transformer for forming a pulse width duty cycle signal by performing a pulse width modulation based on said current signal;
• d. delay circuit means connected to said pulse width modulation circuit for producing a delayed pulse width duty cycle signal by delaying said pulse width duty cycle signal by a delay time period specified in accordance with said kind of electric energy to be measured;
• e. delay time setting circuit means connected to said delay circuit and at least one of said voltage transformer and said current transformer for setting said delay time period in said delay circuit;
• f. a time division multiplying circuit connected through said delay circuit means to said pulse width modification circuit and to said voltage transformer, which receives said delayed pulse width duty cycle signal and multiplies said voltage signal and said delayed pulse width duty cycle signal to obtain an electric power signal proportional to the electric power on said power lines corresponding to said kind of energy;
• g. an integration circuit connected to said time division multiplying circuit for producing an electric energy signal proportional to said kind of electric energy by integrating said electric power signal;
• h. a processing circuit connected to said integration circuit for converting said electric energy signal to a display signal;
• and
• i. a display circuit connected to said processing circuit for displaying a measure of said kind of electric energy in accordance with said display signal.