INTEGRATION TYPE MULTI-PHASE WATTMETER

摘要

PURPOSE: To obtain a signal having an amplitude proportional to the current of a distribution system and a pulse width proportional to the voltage of the system by generating a pulse width-modulated signal from the voltage of the system and a triangular-wave signal and controlling a CMOS switch by using the generated signal. CONSTITUTION: A transformer 20 is connected between distribution lines 16 and 18 and a current transformer 24 is connected to a current path to an application 15. The output of the transformer 20 is connected to one input of a comparator 30 and a triangular-wave generator 35 is connected to the other input of the comparator 30 so that a pulse having a width proportional to the voltage can be obtained. The output of the comparator 30 and a sign bit NP are connected to the control input of a CMOS switch 40 through an EXOR circuit 45. The transformer 24 and a current-to-frequency converter 50 are respectively connected to both ends of the switch 40 through resistors R1 and R2. Therefore, a signal having an amplitude accurately proportional to the current and a pulse width proportional to the voltage can be inputted to the converter 50.